The brain is responsible for the nerves. Cranial (cranial) nerves. B) in the neck

The person has 12 pairs of cranial nerves(see diagrams below). Scheme of localization of the nuclei of cranial nerves: anteroposterior (a) and lateral (b) projections
The red color indicates the nuclei of the motor nerves, blue - sensitive, green - the nuclei of the vestibulocochlear nerve

Olfactory, visual, vestibulocochlear - nerves of highly organized specific sensitivity, which in their morphological features represent, as it were, peripheral parts of the central nervous system.

The article below will list all 12 pairs of cranial nerves, information about which will be accompanied by tables, diagrams and figures.

For more convenient navigation through the article, there is a picture with clickable links above: just click on the name of the pair of CNs you are interested in and you will immediately go to information about it.

12 pairs of cranial nerves

1 pair of cranial nerves - olfactory (nn. olfactorii)

2 pair of cranial nerves - visual (n. opticus)

With damage to the 2nd pair of cranial nerves, various types of visual impairment can be observed, shown in the figure below.

Any pathology of the optic nerve requires a mandatory check of the fundus, the possible results of which are shown in the figure below.

Fundus examination

3 pair of cranial nerves - oculomotor (n. oculomotorius)

Innervation of the muscles of the eye

3rd pair of cranial nerves is involved in the innervation of the muscles involved in the movement of the eye.

- this is a complex reflex act, in which not only 3 pairs, but also 2 pairs of cranial nerves participate. The diagram of this reflex is shown in the figure above.

4 pair of cranial nerves - block (n. trochlearis)

5 pair of cranial nerves - trigeminal (n. trigeminus)

The dendrites of sensitive cells form three nerves along their course (see the innervation zones in the figure below):

• orbital- (zone 1 in the figure),
• maxillary- (zone 2 in the figure),
• mandibular- (zone 3 in the figure).

From skull n. ophthalmicus exits through fissura orbitalis superior, n. maxillaris - through foramen rotundum, n. mandibularis - through the foramen ovale. As part of one of the branches n. mandibularis, which is called n. lingualis, and chorda tympani taste fibers are suitable for the sublingual and mandibular glands.

When involved in the process of the trigeminal node, all types of sensitivity suffer. This is usually accompanied by excruciating pain and the appearance of herpes zoster on the face.

When involved in the pathological process of the nucleus n. trigeminus, located in the spinal tract, the clinic is accompanied by dissociated anesthesia or hypesthesia. With a partial lesion, segmental annular zones of anesthesia are noted, known in medicine under the name of the scientist who discovered them " Zelder zones" (see diagram). When the upper parts of the nucleus are affected, the sensitivity around the mouth and nose is disturbed; lower - outer parts of the face. Processes in the nucleus are usually not accompanied by pain.

6 pair of cranial nerves - abducens (n. abducens)

Abducens nerve (n. abducens) - motor. The nerve nucleus is located in the inferior part of the pons, under the floor of the fourth ventricle, lateral and dorsal to the dorsal longitudinal bundle.

Damage to the 3rd, 4th, and 6th pairs of cranial nerves causes total ophthalmoplegia. With paralysis of all the muscles of the eye, there is external ophthalmoplegia.

The defeat of the above pairs, as a rule, is peripheral.

Eye innervation

Without the friendly functioning of several components of the muscular apparatus of the eye, it would be impossible to carry out the movements of the eyeballs. The main formation, thanks to which the eye can move, is the dorsal longitudinal bundle of fasciculus longitudinalis, which is a system that connects the 3rd, 4th and 6th cranial nerves with each other and with other analyzers. Cells of the nucleus of the dorsal longitudinal bundle (Darkshevich) are located in the cerebral peduncles laterally from the cerebral aqueduct, on the dorsal surface in the region of the posterior commissure of the brain and frenulum. The fibers go down along the aqueduct of the large brain to the rhomboid fossa and on their way approach the cells of the nuclei of 3, 4 and 6 pairs, carrying out the connection between them and the coordinated function of the eye muscles. The composition of the dorsal bundle includes fibers from the cells of the vestibular nucleus (Deiters), which form the ascending and descending pathways. The first are in contact with the cells of the nuclei of 3, 4 and 6 pairs, the descending branches stretch down, pass in the composition, which end at the cells of the anterior horns, forming tractus vestibulospinalis. The cortical center, which regulates voluntary gaze movements, is located in the region of the middle frontal gyrus. The exact course of the conductors from the cortex is unknown; apparently, they go to the opposite side to the nuclei of the dorsal longitudinal bundle, then along the dorsal bundle to the nuclei of these nerves.

Through the vestibular nuclei, the dorsal longitudinal bundle is connected with the vestibular apparatus and the cerebellum, as well as with the extrapyramidal part of the nervous system, through the tractus vestibulospinalis - with the spinal cord.

7 pair of cranial nerves - facial (n. facialis)

The scheme of the topography of the facial nerve is presented above.

Intermediate nerve (n. intermedius)

The intermediate nerve is essentially part of the facial.

With damage to the facial nerve, or rather its motor roots, there is paralysis of the mimic muscles of the peripheral type. The central type of paralysis is a rare phenomenon and is observed when the pathological focus is localized in, in particular, in the precentral gyrus. The differences between the two types of mimic muscle paralysis are shown in the figure above.

8 pair of cranial nerves - vestibulocochlear (n. vestibulocochlearis)

The vestibulocochlear nerve anatomically has two roots with completely different functional abilities (this is reflected in the name of the 8th pair):

1. pars cochlearis, performing the auditory function;
2. pars vestibularis, which performs the function of a static feeling.

Pars cochlearis

Other names for the root: "lower cochlear" or "cochlear part".

The cranial nerves make our lives easier every day, as they provide the functioning of our body and the connection of the brain with the senses.

What it is?

How many of them are there and what functions does each of them perform? How are they classified?

General information

The cranial nerve is a collection of nerves that begin or end in the brain stem. There are 12 nerve pairs in total. Their numbering is based on the order of release:

• I - responsible for the sense of smell
• II - responsible for vision
• III - allows the eyes to move
• IV - directs the eyeball down and outward;
• V - is responsible for the measure of sensitivity of facial tissues.
• VI - abducts the eyeball
• VII - connects the facial muscles and lacrimal glands with the central nervous system (central nervous system);
• VIII - transmits auditory impulses, as well as impulses emitted by the vestibular part of the inner ear;
• IX - sets in motion the stylo-pharyngeal muscle, which lifts the pharynx, connects the parotid gland with the central nervous system, makes the tonsils, pharynx, soft palate, etc. sensitive;
• X - innervates the chest and abdominal cavities, cervical organs and organs of the head;
• XI - provides nerve cells to muscle tissues that turn the head and raise the shoulder;
• XII - responsible for the movements of the tongue muscles.

Leaving the area of ​​the brain, the cranial nerves go to the skull, which has characteristic openings under them. Through them they go out, and then there is a branching.

Each of the nerves of the skull is different both in composition and functionality.

How does it differ from, for example, the nerve of the spinal cord: the nerves of the spinal cord are predominantly mixed, and diverge only in the peripheral region, where they are divided into 2 types. FMN are either one or the other type and in most cases are not mixed. Pairs I, II, VIII are sensory, and III, IV, VI, XI, XII are motor. The rest are mixed.

Classification

There are 2 fundamental classifications of nerve pairs: by location and functionality:
Exit location:

• emerging above the brain stem: I, II;
• the exit point is the midbrain: III, IV;
• the exit point is the Varoliev Bridge: VIII, VII, VI, V;
• the exit point is the medulla oblongata, or rather its bulb: IX,X,XII and XI.

By functional purpose:

• perception functions: I, II, VI, VIII;
• motor activity of the eyes and eyelids: III, IV, VI;
• motor activity of the cervical and tongue muscles: XI and XII
• parasympathetic functions: III, VII, IX, X

Let's take a closer look at the functionality:

ChMN functionality

sensitive group

I - olfactory nerve.
It consists of receptors, which are thin processes, thickening towards the end. On the ends of the processes there are special hairs that capture odors.
II - the nerve of vision.
It runs through the entire eye, ending in the canal of vision. At the exit from it, the nerves cross, after which they continue their movement to the central part of the brain. The nerve of vision delivers signals received from the outside world to the desired compartments of the brain.
VIII - vestibulocochlear nerve.
Belongs to the sensory type. Consists of 2 components, different in their functionality. The first conducts impulses coming from the vestibule of the inner ear, and the second transmits hearing impulses that come from the cochlea. In addition, the vestibular component is involved in regulating the position of the body, arms, legs and head and, in general, coordinates movements.

motor group

III - oculomotor nerve.

These are processes of nuclei. Runs from the midbrain to the orbit. Its function is to engage the muscles of the eyelash, which carry out accommodation, and the muscle that constricts the pupil.

IV - trochlear nerve.

Refers to the motor type, is located in the orbit, getting there through the gap from above (on the side of the previous nerve). It ends at the eyeball, or rather its upper muscle, which it provides with nerve cells.

VI - abducens nerve.

Like the block one, it is motorized. It is formed by shoots. It is located in the eye, where it penetrates from above, and provides nerve cells to the outer muscle of the eye.

XI - accessory nerve.

Representative of the motor type. dual core. The nuclei are located in the spinal cord and medulla oblongata.

XII - hypoglossal nerve.

Type - motor. Nucleus in the medulla oblongata. Provides nerve cells to the muscles and muscles of the tongue and some parts of the neck.

mixed group

V - trigeminal.

thickness leader. It got its name because it has several branches: ophthalmic, lower and maxillary.

VII - facial nerve.

It has a front and an intermediate component. The facial nerve forms 3 branches and provides normal movement of the muscles of the face.

IX - glossopharyngeal nerve.

Belongs to the mixed type. Consists of three types of fibers.

X - vagus nerve.

Another representative of the mixed type. Its length exceeds the length of the others. Consists of three types of fibers. One branch is the depressor nerve, ending in the aortic arch, which regulates blood pressure. The remaining branches, which have a higher susceptibility, provide nerve cells for the brain membrane and the skin of the ears.

It can be divided (conditionally) into 4 parts: the head section, the neck section, the chest section and the abdominal section. Branches extending from the head are sent to the brain and are called meningeal. And those that go to the ears - ear. The pharyngeal branches come from the neck, and the cardiac branches and thoracic branches, respectively, depart from the chest. Branches directed to the plexus of the esophagus are called esophageal.

What can defeat lead to?

Symptoms of lesions depend on which nerve was damaged:

Olfactory nerve

Symptoms are more or less pronounced, depending on the strength of the nerve lesion. Basically, the lesion is manifested in the fact that a person either smells more sharply, or does not distinguish between them, or does not feel at all. In a special place, you can put cases when symptoms appear only on one side, since their bilateral manifestation usually means that a person has chronic rhinitis

optic nerve

If it is struck, vision deteriorates up to blindness on the side where it happened. If part of the retinal neurons is affected or when a scotoma is formed, there is a risk of local loss of vision in a certain area of ​​the eye. If blindness develops bilaterally, this means that the optic fibers were affected at the crosshairs. If there is damage to the middle visual fibers, which completely intersect, then half of the visual field may fall out.

However, there are also cases when the visual field falls out in only one eye. This is usually due to damage to the optic tract itself.

oculomotor nerve

When the nerve trunk is affected, the eyes stop moving. If only part of the nucleus is affected, then the external muscle of the eye becomes immobilized or very weak. If, nevertheless, complete paralysis has come, then the patient has no way to open his eyes (eyes). If the muscle responsible for lifting the eyelid is very weak, but still functioning, the patient will be able to open the eye, but only partially. The muscle that lifts the eyelid is usually the last to be damaged. But if the damage has reached it, then this can cause divergent strabismus or external ophthalmoplegia.

Block nerve

The defeat of this pair is quite rare. It is expressed in the fact that the eyeball loses the ability to move freely outward and down. This happens due to a violation of innervation. The eyeball seems to freeze in a position turned inward and upward. A characteristic feature of such damage will be bifurcation or diplopia, when the patient tries to look down, to the right, or to the left.

Trigeminal nerve

The main symptom is a segmental disturbance of perception. Sometimes sensitivity to pain or temperature can be completely lost. At the same time, the feeling of a change in pressure or other deeper changes are perceived adequately.

If the facial nerve is inflamed, then that half of the face that was affected hurts. The pain is localized in the ear region. Sometimes the pain can move to the lips, forehead or lower jaw. If the optic nerve is affected, then the corneal and superciliary reflexes disappear.

In cases of damage to the mandibular nerve, the tongue almost completely (on 2/3 of its area) loses the ability to distinguish tastes, and if its motor fiber is damaged, it can paralyze the masticatory muscles.

Abducens nerve

The main symptom is convergent strabismus. Most often, patients complain that they see double in their eyes, and those objects that are located horizontally double.

However, the defeat of this particular pair separately from others is rare. Most often, 3 pairs of nerves (III, IV and VI) are affected at once, due to the proximity of their fibers. But if the lesion has already occurred at the exit of the skull, then most likely the lesion will reach the nominal abducens nerve, in view of its greater length in comparison with the others.

facial nerve

If the motor fibers are damaged, it can paralyze the face. Facial paralysis occurs on the affected half, which is manifested in facial asymmetry. This is complemented by Bell's syndrome - when you try to close the affected half - the eyeball turns up.

Since one half of the face is paralyzed, the eye does not blink and begins to water - this is called paralytic lacrimation. Mimic muscles can also be immobilized if the motor nucleus of the nerve is damaged. If the lesion has also affected the radicular fibers, then this is fraught with the manifestation of the Miyar-Gubler syndrome, which manifests itself in blocking the movement of the arms and legs in the unaffected half.

Vestibulocochlear nerve

With damage to the nerve fibers, hearing is not lost at all.
However, various auditory, irritation and hearing loss, up to deafness, can easily manifest themselves when the nerve itself is damaged. Hearing acuity is reduced if the lesion is receptor in nature or if the anterior or posterior nucleus of the cochlear component of the nerve is damaged.

Glossopharyngeal nerve

If he is struck by the back of the tongue, he ceases to distinguish tastes, the top of the throat loses its susceptibility, the person confuses tastes. Loss of taste is most likely with damage to the projection cortical areas. If the nerve is directly irritated, then the patient feels a burning pain of ragged intensity in the tonsils and tongue, at intervals of 1-2 minutes. Pain can also radiate to the ear and throat. On palpation, more often between attacks, the pain sensation is most severe behind the lower jaw.

Nervus vagus

If it is affected, the esophageal and swallowing muscles are paralyzed. It becomes impossible to swallow, and liquid food enters the nasal cavity. The patient speaks through the nose, wheezing, as the vocal cords are also paralyzed. If the nerve is affected on both sides, then a suffocating effect may occur. Bari- and tachycardia begins, breathing is disturbed and a malfunction of the heart may occur.

accessory nerve

If the lesion is one-sided, then it becomes difficult for the patient to raise his shoulders, his head does not turn to the side that is opposite to the affected area. But in the direction of the affected area, she leans willingly. If the lesion is bilateral, then the head cannot turn in one direction, and is thrown back.

hypoglossal nerve

If it is affected, then the tongue will be completely or partially paralyzed. Paralysis of the periphery of the tongue is most likely if the nucleus or nerve fibers are affected. If the lesion is unilateral, the functionality of the tongue is slightly reduced, but if it is bilateral, the tongue paralyzes, and at the same time it can paralyze the limbs.

5.1. cranial nerves

In the formation of the clinical symptom complex in case of damage to any cranial nerve, not only its peripheral structures, which in anatomical terms represent the cranial nerve, but also other formations in the brainstem, in the subcortical region, cerebral hemispheres, including certain areas of the cerebral cortex, take part.

For medical practice, it is important to determine the area in which the pathological process is located - from the nerve itself to its cortical representation. In this regard, we can talk about a system that provides the function of the cranial nerve.

Among the 12 pairs of cranial nerves (Fig. 5.1), 3 pairs are only sensory (I, II, VIII), 5 pairs are motor (III, IV, VI, XI, XII) and 4 pairs are mixed (V, VII, IX, x). As part of III, V, VII, IX, X pairs there are many vegetative fibers. Sensitive fibers are also present in pair XII.

The system of sensory nerves is a homologue of segmental sensitivity of other parts of the body, providing proprio- and extraceptive sensitivity. The motor nerve system is part of the pyramidal cortico-muscular tract. In this regard, the sensory nerve system, like the system that provides sensitivity to any part of the body, consists of a chain of three neurons, and the motor nerve system, like the cortical-spinal tract, consists of two neurons.

Olfactory nerve - n. olfactorius (I pair)

Olfactory perception is a chemically mediated process. Olfactory receptors are localized on the cilia of the dendrites of bipolar neurons, which significantly increase the surface of the olfactory epithelium and thereby increase the likelihood of capturing an odorous substance molecule. The binding of a molecule of an odorous substance to the olfactory

Rice. 5.1. Base of the brain with cranial nerve roots. 1 - pituitary gland; 2 - olfactory nerve; 3 - optic nerve; 4 - oculomotor nerve; 5 - block nerve; 6 - abducens nerve; 7 - motor root of the trigeminal nerve; 8 - sensitive root of the trigeminal nerve; 9 - facial nerve; 10 - intermediate nerve; 11 - vestibulocochlear nerve; 12 - glossopharyngeal nerve; 13 - vagus nerve; 14 - accessory nerve; 15 - hypoglossal nerve; 16 - spinal roots of the accessory nerve; 17 - medulla oblongata; 18 - cerebellum; 19 - trigeminal knot; 20 - leg of the brain; 21 - optic tract

receptor causes activation of its associated G-protein, which leads to the activation of type III adenylate cyclase. Type III adenylate cyclase hydrolyzes ATP to cAMP, which binds to a specific ion channel and activates it, causing an influx of sodium and calcium ions into the cell in accordance with electrochemical gradients. Depolarization of the receptor membranes leads to the generation of action potentials, which are then conducted along the olfactory nerve.

Structurally, the olfactory analyzer is not homologous to the rest of the cranial nerves, as it is formed as a result of protrusion of the wall of the cerebral bladder. It is part of the olfactory system, which consists of three neurons. The first neurons are bipolar cells located in the mucous membrane of the upper part of the nasal cavity (Fig. 5.2). The unmyelinated processes of these cells form on each side about 20 branches (olfactory filaments) that pass through the ethmoid plate of the ethmoid bone (Fig. 5.3) and enter the olfactory bulb. These threads are actually olfactory nerves. The bodies of the second neurons lie in paired olfactory bulbs, their myelinated processes form the olfactory tract and terminate in the primary olfactory cortex (periamygdala and subcallosal areas), lateral olfactory gyrus, amygdala

Rice. 5.2. Olfactory nerves. 1 - olfactory epithelium, bipolar olfactory cells; 2 - olfactory bulb; 3 - medial olfactory strip; 4 - lateral olfactory strip; 5 - medial bundle of the forebrain; 6 - rear longitudinal beam; 7 - reticular formation; 8 - pear-shaped area; 9 - field 28 (entorhinal region); 10 - hook and amygdala

prominent body (corpus amygdaloideum) and nuclei of the septum pellucidum. The axons of the third neurons located in the primary olfactory cortex end in the anterior part of the parahippocampal gyrus (entorhinal region, field 28) and the hook (uncus) the cortical area of ​​the projection fields and the associative zone of the olfactory system. It should be borne in mind that the third neurons are connected with the cortical projection fields of both their own and the opposite side. The passage of some of the fibers to the other side occurs through the anterior commissure, which connects the olfactory regions and the temporal lobes of both hemispheres of the brain, and also provides communication with the limbic system.

The olfactory system, through the medial bundle of the forebrain and the brain strips of the thalamus, is connected with the hypothalamus, the autonomic zones of the reticular formation, with the salivary nuclei and the dorsal nucleus of the vagus nerve. The connections of the olfactory system with the thalamus, hypothalamus and limbic system provide emotional coloring of olfactory sensations.

Research methodology. With calm breathing and closed eyes, the wing of the nose is pressed with a finger on one side and the odorous substance is gradually brought closer to the other nasal passage, which the subject must identify. Use laundry soap, rose water (or cologne), bitter almond water (or valerian drops), tea, coffee. The use of irritating substances (ammonia, vinegar) should be avoided, as this simultaneously causes irritation of the endings of the trigeminal nerve. It must be borne in mind whether the nasal passages are free or there are catarrhal discharges. Although the subject may not name the test substance, odor awareness precludes the absence of smell.

Rice. 5.3. Openings of the inner base of the skull.

1- ethmoid plate of the ethmoid bone (olfactory nerves); 2 - optic canal (optic nerve, ophthalmic artery); 3 - superior orbital fissure (oculomotor, trochlear, abducens nerves), ophthalmic nerve - I branch of the trigeminal nerve; 4 - round hole (maxillary nerve -

II branch of the trigeminal nerve); 5 - oval hole (mandibular nerve - III branch of the trigeminal nerve); 6 - torn hole (sympathetic nerve, internal carotid artery); 7 - spinous foramen (middle meningeal arteries and veins); 8 - stony hole (lower stony nerve); 9 - internal auditory opening (facial, vestibulocochlear nerves, labyrinth artery); 10 - jugular foramen (glossopharyngeal, vagus, accessory nerves); 11 - hypoglossal canal (hyoid nerve); 12 - foramen magnum (spinal cord, meninges, spinal roots of the accessory nerve, vertebral artery, anterior and posterior spinal arteries). The frontal bone is indicated in green, the ethmoid bone in brown, the sphenoid bone in yellow, the parietal bone in purple, the temporal bone in red, and the occipital bone in blue.

Damage symptoms. Lack of smell - anosmia. Bilateral anosmia is observed with an infectious lesion of the upper respiratory tract, rhinitis, fractures of the bones of the anterior cranial fossa with a break in the olfactory filaments. Unilateral anosmia may be of diagnostic value in tumors of the base of the frontal lobe. Hyperosmia- An increased sense of smell is noted in some forms of hysteria and sometimes in cocaine addicts. Parosmia- a perverted sense of smell is observed in some cases of schizophrenia, hysteria, with damage to the parahippocampal gyrus. Olfactory hallucinations in the form of odor sensations are observed in some psychoses, epileptic seizures caused by damage to the parahippocampal gyrus (possibly in the form of an aura - an olfactory sensation that is a harbinger of an epileptic seizure).

optic nerve - n. opticus (II pair)

The visual analyzer realizes the transformation of light energy into an electrical impulse in the form of an action potential of the photoreceptor cells of the retina, and then into a visual image. There are two main types of photoreceptors located in the intermediate

the exact layer of the retina, the rods and cones. Rods are responsible for vision in the dark, they are widely represented in all parts of the retina and are sensitive to low light. The transmission of information from the rods does not allow us to distinguish colors. Most of the cones are located in the fovea; they contain three different visual pigments and are responsible for day vision, color vision. Photoreceptors form synapses with horizontal and bipolar retinal cells.

Horizontal cells receive signals from many, providing a sufficient influx of information to generate a receptive field. Bipolar cells respond to a small beam of light at the center of the receptive field (de- or hyperpolarization) and relay information from photoreceptors to ganglion cells. Depending on the receptors with which they form synapses, bipolar cells are divided into carrying information only from cones, only from rods, or from both.

ganglion cells, forming synapses with bipolar and amacrine cells of the retina, are located near the vitreous body. Their myelinated processes form the optic nerve, which, passing through the inner surface of the retina, forms the optic disc ("blind spot", where there are no receptors). About 80% of ganglion cells are X-cells responsible for distinguishing details and color; 10% of Y-type ganglion cells are responsible for the perception of movement, the functions of 10% of W-type ganglion cells have not been determined, but their axons are known to project into the brainstem.

Formed by axons of ganglion cells optic nerve enters through the optic canal into the cranial cavity, goes along the base of the brain and anterior to the Turkish saddle, where it forms the optic chiasm (chiasma opticum). Here the fibers from the nasal half of the retina of each eye are decussated, while the fibers from the temporal half of the retina of each eye remain uncrossed. After crossing, the fibers from the same halves of the retina of both eyes form the visual tracts (Fig. 5.4). As a result, fibers from both left halves of the retina pass in the left optic tract, and from the right halves in the right. When light rays pass through the refractive media of the eye, an inverted image is projected onto the retina. As a result, the visual tracts and the formations of the visual analyzer located above receive information from opposite halves of the visual fields.

In the future, the visual tracts from the base rise upward, bending around the legs of the brain from the outside, and approach the external geniculate bodies, the top

Rice. 5.4. Visual analyzer and main types of visual field disorders (diagram).

1 - field of view; 2 - horizontal section of the fields of view; 3 - retina; 4 - right optic nerve; 5 - optic chiasm; 6 - right visual tract; 7 - lateral geniculate body; 8 - upper tubercle; 9 - visual radiance; 10 - the cortex of the occipital lobe of the brain. Localization of the lesion: I, II - optic nerve; III - internal sections of the optic chiasm; IV - right outer section of the optic chiasm; V - left visual tract; VI - left thalamocortical visual pathway; VII - the upper part of the visual radiation on the left. Damage symptoms: a - concentric narrowing of the visual fields (tubular vision); occurs with hysteria, optic neuritis, retrobulbar neuritis, opto-chiasmatic arachnoiditis, glaucoma; b - complete blindness in the right eye; occurs with a complete interruption of the right optic nerve (for example, with trauma); c - bitemporal hemianopsia; occurs with lesions of the chiasm (for example, with tumors of the pituitary gland); d - right-sided nasal hemianopsia; may occur when the perichiasmal region is damaged due to an aneurysm of the right internal carotid artery; e - right-sided homonymous hemianopsia; occurs when the parietal or temporal lobe is damaged with compression of the left visual tract; f - right-sided homonymous hemianopia (with preservation of the central field of view); occurs when the entire left visual radiation is involved in the pathological process; g - right-sided lower quadrant homonymous hemianopsia; arises due to partial involvement in the process of visual radiation (in this case, the upper portion of the left visual radiation)

them to the tubercles of the quadrigemina of the midbrain and the pretectal region. The main part of the fibers of the optic tract enters into external geniculate body consisting of six layers, each of which receives impulses from the retina of its or the opposite side. The two inner layers of large neurons form large cell plates, the remaining four layers are small cell plates, with intralaminar regions located between them (Fig. 5.5). Large and small cell plates differ morphologically and electrophysiologically. Large cell neurons respond to spatial differences, movement, without performing the function of color discrimination; their properties are similar to those of the Y-retina ganglion cells. Small cell neurons are responsible for color perception and high spatial resolution of the image, i.e. their properties are close to those of X-retinal ganglion cells. Thus, there are topographic features in the representation of projections from ganglion cells of different types in the retinogenicular tract and the lateral geniculate body. Ganglion X cells and small cell neurons responsible for color and shape perception (pattern- P), form the so-called P-channel of the visual analyzer. Ganglion Y cells and large cell neurons responsible for motion perception (movement- M), form the M-channel of the visual analyzer.

The axons of the neurons of the external geniculate body, having formed visual radiation, approach the primary projection visual area of ​​the cortex - the medial surface of the occipital lobe along the spur groove (field 17). It is important to note that the P- and M-channels form synapses with different structures of the IV and, to a lesser extent, VI layers of the cortex, and the intralaminar

nye parts of the external geniculate body - with II and III layers of the cortex.

The cortical neurons of layer IV of the primary visual cortex are organized according to the principle of a circular symmetrical receptive field. Their axons project onto the neurons of the adjacent cortex, with several neurons in the primary visual cortex converging (converging) to a single cell in the adjacent area. As a result, the receptive field of the “neighboring” neuron with the visual projection cortex becomes

Rice. 5.5. Organization of the lateral geniculate body

is more complex in terms of its activation pathway compared to the field of a neuron in the primary visual cortex. These cells, however, refer to "simple" cortical neurons that respond to a light threshold in a certain orientation. Their axons converge to neurons of layers III and II of the cortex (“complex” cortical neurons), which are maximally activated not only by stimuli of a certain orientation, but also by stimuli moving in a certain direction. "Complex" cells are projected onto "supercomplex" (or "final") cells that respond to stimuli not only of a certain orientation, but also of length. "Supercomplex" cells function hierarchically (each cell receives its receptive field from the one below it) and are organized into cell columns (columns). Cell columns unite neurons with similar properties depending on the side of the light stimulus (from the homolateral retina - "columns selective along the side"), on its spatial orientation ("columns selective in orientation"). Columns of two different types are located at right angles to each other, making up a single "hypercolumn", which has a size of about 1 mm 3 and is responsible for the analysis of information that came from a certain zone of the field of view of one eye.

In the cortex, visual information is processed not only according to the principle of hierarchical convergence of neurons, but also in parallel ways. The projection zones of the P- and M-channels of the visual analyzer are important, as well as the projections of the layers of the primary visual cortex onto the secondary and extrastriate zones. Extrastriatal cortical fields are located outside the zone of the primary visual cortex (fields 18 and 19 on the convexital surface of the occipital lobe, lower temporal region), but are primarily involved in the processing of visual information, providing a more complex processing of the visual image. More distant zones of the central nervous system also take part in the analysis of visual information: the posterior parietal cortex, the frontal cortex, including the zone of the cortical center of gaze, the subcortical structures of the hypothalamus, and the upper sections of the brain stem.

In the cortical visual field, as well as in the optic radiation, optic nerve and optic tract, the fibers are arranged in a retinotopic order: from the upper retinal fields they go to the upper sections, and from the lower retinal fields - to the lower sections.

superior tubercles of the quadrigemina the midbrain perform the functions of the subcortical center of vision. They are multilayer formations in which the surface layers are responsible for the distribution

visual fields, and deep - for the integration of visual, auditory and somatosensory stimuli through the tectobulbar and tectospinal paths to other cranial and spinal nuclei. Intermediate layers are connected with the occipital-parietal cortex, the cortical center of the gaze of the frontal lobe, the substantia nigra; they take part in the implementation of eye movements when switching gaze from one object to another, are responsible for involuntary oculoskeletal reflexes, combined movements of the eyeballs and head in response to visual stimulation.

The visual analyzer has connections with pretectal structures - the nuclei of the midbrain, projected onto the Yakubovich-Edinger-Westphal nuclei, providing parasympathetic innervation to the muscle that narrows the pupil. As a result, light falling on the retina leads to a constriction of both pupils (on its side - a direct reaction to light, on the opposite side - a friendly reaction to light). With the defeat of one optic nerve, the direct and friendly reaction of the pupils to light is lost with light stimulation from the affected side. The pupil of the affected side will actively contract with light stimulation of the opposite eye (the so-called relative afferent pupillary defect).

Research methodology. To judge the state of vision, it is necessary to examine visual acuity, visual field, color perception and the fundus of the eye.

Visual acuity (visus) is determined for each eye separately using standard text tables or maps, computerized systems. In patients with a pronounced decrease in vision, the count or movement of the fingers in the face, the perception of light are evaluated.

Visual fields (perimetry) are examined for white and red, less often for green and blue. Normal boundaries of the visual field for white: upper - 60°, inner - 60°, lower - 70°, outer - 90°; to red - 40, 40, 40 and 50 °, respectively.

With an approximate determination of the visual fields, the doctor sits opposite the subject (it is advisable to seat the patient with his back to the light source) and asks him to close his eye with his palm, without pressing on the eyeball. The second eye of the patient should be open, and the gaze is fixed on the nose of the examiner. The patient is asked to report when he sees an object (the examiner's hammer or finger) that leads from the periphery of the circle to its center, which is the patient's eye. When examining the external field of view, the movement begins at the level of the patient's ear. The internal field of view is examined in a similar way, but the object is introduced into the field of view from the medial side.

us. To study the upper limit of the field of view, the hand is placed above the scalp and led from top to bottom. Finally, the lower limit is determined by moving the hand from bottom to front and up.

It is possible to offer the person being examined to indicate the middle of the towel, rope or stick with his finger, while the gaze should be fixed strictly in front of him. When the field of view is limited, the patient divides approximately 3/4 of the object in half due to the fact that about 1/4 of its length falls out of the field of view. Hemianopsia helps to identify the study of the blink reflex. If the examiner suddenly raises his hand from the side of the eye of a patient with a visual field defect (hemianopsia), then blinking will not occur.

Color perception is examined using special polychromatic tables, on which numbers, figures, etc. are depicted as spots of different colors.

Damage symptoms. Decreased visual acuity - amblyopia (ambliopia), complete loss of vision amaurosis. Limited visual field defect that does not reach its borders - scotoma. There are positive and negative scotomas. Positive (subjective) scotomas are such visual field defects that the patient himself sees as a dark spot covering part of the object in question. A positive scotoma indicates damage to the inner layers of the retina or vitreous just in front of the retina. The patient does not notice negative scotomas - they are found only when examining the visual field. Typically, such scotomas occur when the optic nerve or more highly located parts of the visual analyzer are damaged. According to topography, central, paracentral and peripheral scotomas are distinguished. Bilateral scotomas located in the same or opposite halves of the visual field are called homonymous (similar) or heteronymous (opposite). With small focal lesions of the visual pathways in the region of the optic chiasm, heteronymous bitemporal, less often binasal scotomas are observed. With the localization of a small pathological focus above the optic chiasm (optic radiation, subcortical and cortical visual centers), homonymous paracentral or central scotomas develop on the side opposite to the pathological focus.

Loss of half of the field of view - hemianopsia. With the loss of the same (both right or both left) halves of the visual fields, they speak of homonymous hemianopsia. If both internal (nasal) or both external (temporal) halves of the visual fields fall out, such

hemianopsia is called heteronymous (heteronymous). Loss of the outer (temporal) halves of the visual fields is referred to as bitemporal hemianopsia, and the inner (nasal) halves of the visual fields as binasal hemianopsia.

visual hallucinations are simple (photopsies in the form of spots, colored highlights, stars, stripes, flashes) and complex (in the form of figures, faces, animals, flowers, scenes).

Visual disorders depend on the localization of the visual analyzer. With damage to the optic nerve in the area from the retina to the chiasm, a decrease in vision or amaurosis of the corresponding eye develops with the loss of a direct pupillary response to light. A friendly reaction is preserved (the pupil narrows to light when the healthy eye is illuminated). The defeat of only part of the fibers of the optic nerve is manifested by scotomas. Atrophy of the macular (going from the macula) fibers is manifested by blanching of the temporal half of the optic disc during ophthalmoscopy, it can be combined with a deterioration in central vision while maintaining peripheral vision. Damage to the peripheral fibers of the optic nerve (periaxial nerve injury) leads to a narrowing of the field of peripheral vision while maintaining visual acuity. Complete damage to the nerve, leading to its atrophy and amaurosis, is accompanied by blanching of the entire optic nerve head. Intraocular diseases (retinitis, cataracts, corneal lesions, atherosclerotic changes in the retina, etc.) may also be accompanied by a decrease in visual acuity.

Distinguish between primary and secondary atrophy of the optic nerve, while the optic disc becomes light pink, white or gray. Primary atrophy of the optic disc is caused by processes that directly affect the optic nerve (tumor compression, intoxication with methyl alcohol, lead). Secondary atrophy of the optic nerve is a consequence of edema of the optic disc (glaucoma, intracranial hypertension, with a volumetric brain lesion - tumors, abscesses, hemorrhages).

With a complete lesion of the chiasm, bilateral amaurosis occurs. If the central part of the chiasm is affected (with a pituitary tumor, craniopharyngioma, meningioma of the sella turcica), the fibers coming from the inner halves of the retina of both eyes suffer. Accordingly, the external (temporal) visual fields fall out (bitemporal heterogeneous hemianopsia). When the outer parts of the chiasm are damaged (with aneurysm of the carotid arteries), fibers coming from the outer parts of the retina fall out.

ki, which correspond to the internal (nasal) visual fields, and clinically develops opposite bilateral binasal hemianopsia.

With damage to the optic tract in the area from the chiasm to the subcortical visual centers, the geniculate body and the cortical visual center, the hemianopsia of the same name develops, the visual fields opposite to the affected optic tract fall out. Thus, damage to the left optic tract will cause immunity to illumination of the outer half of the retina of the left eye and the inner half of the retina of the right eye with the development of the right-sided hemianopsia of the same name. On the contrary, with damage to the optic tract on the right, the left halves of the visual fields fall out - the left-sided hemianopsia of the same name occurs. Significant asymmetry of visual field defects is possible due to uneven damage to the fibers with partial damage to the optic tract. In some cases, there is a positive central scotoma due to impaired macular vision - involvement in the pathological process of the papillomacular bundle passing through the tract.

To recognize the level of the lesion, the reaction of the pupils to light is important. If, with the same hemianopia, there is no reaction to light from the damaged halves of the retina (the study is carried out using a slit lamp), then the lesion is located in the region of the optic tract. If the reaction of the pupils is not disturbed, then the lesion is localized in the area of ​​Graziola's radiance, i.e. above the closure of the pupillary reflex arc.

Damage to the optic radiance (Graziola radiance) causes the opposite homonymous hemianopia. Hemianopsia may be complete, but more often it is incomplete due to the wide distribution of radiation fibers. The fibers of the optic radiation are located compactly only at the exit from the lateral geniculate body. After passing the isthmus of the temporal lobe, they diverge fan-shaped, located in the white matter near the outer wall of the lower and posterior horns of the lateral ventricle. In this regard, with damage to the temporal lobe, a quadrant loss of visual fields can be observed, in particular, upper quadrant hemianopsia due to the passage of the lower part of the visual radiation fibers through the temporal lobe.

With damage to the cortical visual center in the occipital lobe, in the region of the spur groove (sulcus calcarinus), there may be symptoms of both loss (hemianopsia, quadrant loss of the visual field, scotomas) and irritation (photopsia) in opposite visual fields. They may be the result of cerebrovascular accidents.

scheniya, ophthalmic migraine, tumors. It is possible to preserve macular (central) vision. The defeat of individual parts of the occipital lobe (wedge or lingual gyrus) is accompanied by quadrant hemianopsia on the opposite side: the lower one - with the defeat of the wedge and the upper one - with the defeat of the lingual gyrus.

oculomotor nerve - n. oculomotorius (III pair)

The oculomotor nerve is a mixed nerve, the nuclei consist of five cell groups: two external motor large cell nuclei, two small cell nuclei and one internal unpaired small cell nucleus (Fig. 5.6, 5.7).

The motor nuclei of the oculomotor nerves are located anterior to the central gray matter surrounding the aqueduct, and the autonomic nuclei are located within the central gray matter. The nuclei receive impulses from the cortex of the inferior part of the precentral gyrus, which are transmitted through the cortical-nuclear pathways passing in the knee of the internal capsule.

The motor nuclei innervate the external muscles of the eye: the superior rectus muscle (movement of the eyeball up and inwards); lower rectus muscle (movement of the eyeball down and inwards); medial rectus muscle (movement of the eyeball inwards); inferior oblique muscle (movement of the eyeball upward and outward); muscle that lifts the upper eyelid. In each nucleus, the neurons responsible for certain muscles form columns.

Two small-cell accessory Yakubovich-Edinger-Westphal nuclei give rise to parasympathetic fibers that innervate the internal muscle of the eye - the muscle that narrows the pupil (m. sphincter pupillae). The posterior central unpaired nucleus of Perlia is common to both oculomotor nerves and performs convergence of the eye axes and accommodation.

The reflex arc of the pupillary reflex to light: afferent fibers in the optic nerve and optic tract, heading to the upper tubercles of the roof of the midbrain and ending in the nucleus of the pretectal region. The intercalary neurons associated with both accessory nuclei ensure the synchronism of pupillary reflexes to light: illumination of the retina of one eye causes constriction of the pupil of the other, unlit eye. Efferent fibers from the accessory nucleus, together with the oculomotor nerve, enter the orbit and are interrupted in the ciliary node, the postganglionic fibers of which innervate the muscle, narrowing

pupil (m. sphincter pupillae). This reflex does not involve the cerebral cortex.

Part of the axons of motor neurons crosses at the level of the nuclei. Together with uncrossed axons and parasympathetic fibers, they bypass the red nuclei and go to the medial parts of the brain stem, where they combine into the oculomotor nerve. The nerve passes between the posterior cerebral and superior cerebellar arteries. On the way to the orbit, it passes through the subarachnoid space of the basal cistern, pierces the upper wall of the cavernous sinus, and then follows between the sheets of the outer wall of the cavernous sinus, leaving the cranial cavity through the superior orbital fissure.

Penetrating into the orbit, the oculomotor nerve divides into two branches. The superior branch innervates the superior rectus muscle and the levator levator muscle of the upper eyelid. The inferior branch innervates the medial rectus, inferior rectus, and inferior oblique muscles. A parasympathetic root departs from the lower branch to the ciliary node, the preganglionic fibers of which switch inside the node to short postganglionic fibers that innervate the ciliary muscle and the sphincter of the pupil.

Damage symptoms.Ptosis (drooping eyelid) due to para-

Rice. 5.6. Location of cranial nerve nuclei in the brainstem (diagram). 1 - accessory nucleus of the oculomotor nerve; 2 - the nucleus of the oculomotor nerve; 3 - the nucleus of the trochlear nerve; 4 - the motor nucleus of the trigeminal nerve; 5 - the core of the abducens nerve; 6 - the nucleus of the facial nerve; 7 - upper salivary nucleus (VII nerve); 8 - lower salivary nucleus (IX nerve); 9 - posterior nucleus of the vagus nerve; 10 - double core (IX, X nerves); 11 - the nucleus of the hypoglossal nerve; 12 - upper tubercle; 13 - medial geniculate body; 14 - lower tubercle; 15 - the nucleus of the mesencephalic pathway of the trigeminal nerve; 16 - middle cerebellar peduncle; 17 - bridge nucleus of the trigeminal nerve; 18 - facial tubercle; 19 - vestibular nuclei (VIII nerve); 20 - cochlear nuclei (VIII nerve); 21 - the nucleus of a single path (VII, IX nerves); 22 - the nucleus of the spinal tract of the trigeminal nerve; 23 - triangle of the hypoglossal nerve. Motor nuclei are marked in red, sensory nuclei in blue, parasympathetic nuclei in green

Rice. 5.7. Oculomotor nerves.

1 - accessory nucleus of the oculomotor nerve (Yakubovich-Edinger-Westphal nucleus); 2 - large cell nucleus of the oculomotor nerve; 3 - posterior central nucleus of the eye of the motor nerve; 4 - the nucleus of the trochlear nerve; 5 - the nucleus of the outgoing nerve; 6 - oculomotor nerve; 7 - block nerve; 8 - abducens nerve; 9 - ophthalmic nerve (branch of the trigeminal nerve) and its connections with the oculomotor nerves; 10 - upper oblique muscle; 11 - muscle that lifts the upper eyelid; 12 - upper straight muscle; 13 - medial rectus muscle; 14 - short ciliary nerves; 15 - ciliary knot; 16 - lateral rectus muscle; 17 - lower rectus muscle; 18 - lower oblique muscle. Motor fibers are marked in red, parasympathetic in green, sensory in blue

the lich of the muscle that lifts the upper eyelid (Fig. 5.8). Divergent strabismus (strabismus divergens)- setting the eyeball outward and slightly downward due to the action of the unopposed lateral rectus (innervated by the VI pair of cranial nerves) and superior oblique (innervated by the IV pair of cranial nerves) muscles. Diplopia(double vision) is a subjective phenomenon observed when looking with both eyes (binocular vision), while the image of the object being focused in both eyes is obtained not on the corresponding, but on different areas of the retina. Double vision occurs due to the deviation of the visual axis of one eye relative to the other; with monocular vision, it is caused by

Rice. 5.8. Damage to the right oculomotor nerve.

a- ptosis of the right eyelid; b- divergent strabismus, exophthalmos

It is caught, as a rule, by a change in the properties of the refractive media of the eye (cataract, clouding of the lens), mental disorders.

midriaz(pupil dilation) with no pupillary response to light and accommodation, so damage to the visual radiance and visual cortex does not affect this reflex. Paralysis of the muscle that narrows the pupil occurs when the oculomotor nerve, preganglionic fibers, or ciliary ganglion are damaged. As a result, the reflex to light disappears and the pupil dilates, since sympathetic innervation is preserved. The defeat of afferent fibers in the optic nerve leads to the disappearance of the pupillary reflex to light both on the side of the lesion and on the opposite side, since the conjugation of this reaction is interrupted. If at the same time light falls on the contralateral, unaffected eye, then the pupillary reflex to light occurs on both sides.

Paralysis (paresis) of accommodation causes blurred vision at close distances. Afferent impulses from the retina reach the visual cortex, from which efferent impulses are sent through the pretectal region to the accessory nucleus of the oculomotor nerve. From this nucleus, impulses go through the ciliary node to the ciliary muscle. Due to the contraction of the ciliary muscle, the ciliary girdle relaxes and the lens acquires a more convex shape, as a result of which the refractive power of the entire optical system of the eye changes and the image of the approaching vision changes.

the meta is fixed on the retina. When looking into the distance, relaxation of the ciliary muscle leads to a flattening of the lens.

Paralysis (paresis) of convergence the eye is manifested by the inability to turn the eyeballs inwards. Convergence is normally carried out as a result of simultaneous contraction of the medial rectus muscles of both eyes; accompanied by constriction of the pupils (miosis) and tension of accommodation. These three reflexes can be caused by arbitrary fixation on a nearby object. They also arise involuntarily with the sudden approach of a distant object. Afferent impulses travel from the retina to the visual cortex. From there, efferent impulses are sent through the pretectal region to the posterior central nucleus of Perlia. Impulses from this nucleus propagate to neurons that innervate both medial rectus muscles (providing convergence of the eyeballs).

Thus, with complete damage to the oculomotor nerve, paralysis of all external eye muscles occurs, except for the lateral rectus muscle, innervated by the abducens nerve, and the superior oblique muscle, which receives innervation from the trochlear nerve. There also occurs paralysis of the internal eye muscles, their parasympathetic part. This is manifested in the absence of a pupillary reflex to light, pupil dilation, and violations of convergence and accommodation. Partial damage to the oculomotor nerve causes only some of these symptoms.

Block nerve - n. trochlearis (IV pair)

The nuclei of the trochlear nerves are located at the level of the inferior tubercles of the quadrigemina of the midbrain anterior to the central gray matter, below the nuclei of the oculomotor nerve. The internal nerve roots envelop the outer part of the central gray matter and cross in the superior medullary velum, which is a thin plate that forms the roof of the rostral part of the fourth ventricle. After decussation, the nerves leave the midbrain downward from the inferior tubercles. The trochlear nerve is the only nerve that emerges from the dorsal surface of the brainstem. On the way in the central direction to the cavernous sinus, the nerves first pass through the coracoid cerebellopontine fissure, then through the notch of the cerebellum tenon, and then along the outer wall of the cavernous sinus and from there, together with the oculomotor nerve, they enter the orbit through the superior orbital fissure.

Damage symptoms. The trochlear nerve innervates the superior oblique muscle, which rotates the eyeball outwards and downwards. Paralysis of the muscle causes the affected eyeball to deviate upward and somewhat inwards. This deviation is especially noticeable when the affected eye looks down and in a healthy direction, and is clearly manifested when the patient looks at his feet (when walking up the stairs).

abducens nerve - n. abducens (VI pair)

The nuclei of the abducens nerves are located on both sides of the midline in the tire of the lower part of the bridge near the medulla oblongata and under the floor of the IV ventricle. The internal knee of the facial nerve passes between the nucleus of the abducens nerve and the fourth ventricle. The fibers of the abducens nerve go from the nucleus to the base of the brain and exit as a stem at the border of the pons and medulla oblongata at the level of the pyramids. From here, both nerves travel upward through the subarachnoid space on either side of the basilar artery. Then they pass through the subdural space anterior to the clivus, pierce the membrane and join in the cavernous sinus to other oculomotor nerves. Here they are in close contact with the I and II branches of the trigeminal nerve and with the internal carotid artery, which also pass through the cavernous sinus. The nerves are located near the upper lateral parts of the sphenoid and ethmoid sinuses. Further, the abducens nerve goes forward and through the superior orbital fissure enters the orbit and innervates the lateral muscle of the eye, which turns the eyeball outwards.

Damage symptoms. When the abducens nerve is damaged, the outward movement of the eyeball is disturbed. This is because the medial rectus muscle is left without an antagonist and the eyeball deviates towards the nose (converging strabismus - strabismus convergence)(Fig. 5.9). In addition, double vision occurs, especially when looking towards the affected muscle.

Damage to any of the nerves that provide movement of the eyeballs is accompanied by double vision, as the image of the object is projected onto different areas of the retina. The movements of the eyeballs in all directions are carried out due to the friendly action of the six eye muscles on each side. These movements are always very precisely coordinated, because the image is projected mainly to only the two central foveae of the retina (the place of best vision). None of the muscles of the eye is innervated independently of the others.

If all three motor nerves are damaged, the eye is deprived of all movements, looks straight, its pupil is wide and does not react to light (total ophthalmoplegia). Bilateral paralysis of the eye muscles is usually the result of damage to the nuclei of the nerves.

Most often, encephalitis, neurosyphilis, multiple sclerosis, circulatory disorders and tumors lead to damage to the nuclei. The main causes of nerve damage are meningitis, sinusitis, aneurysm of the internal carotid artery, thrombosis of the cavernous sinus and communicating artery, fractures and tumors of the skull base, diabetes mellitus, diphtheria, botulism. It should be borne in mind that transient ptosis and diplopia may develop due to myasthenia gravis.

Only with bilateral and extensive supranuclear processes that spread to the central neurons and go from both hemispheres to the nuclei, bilateral ophthalmoplegia of the central type can occur, since, by analogy with most motor nuclei of the cranial nerves, the nuclei of the III, IV and VI nerves have bilateral cortical innervation.

Eye innervation. Isolated movements of one eye independently of the other in a healthy person are impossible: both eyes always move

at the same time, i.e. a pair of eye muscles always contracts. So, for example, in looking to the right, the lateral rectus muscle of the right eye (abducens nerve) and the medial rectus muscle of the left eye (oculomotor nerve) participate. Combined voluntary eye movements in different directions - the function of the gaze - are provided by the system of the medial longitudinal beam (Fig. 5.10) (fasciculus longitudinalis medialis). The fibers of the medial longitudinal bundle begin in the nucleus of Darkshevich and in the intermediate nucleus, located in the tegmentum of the midbrain above the nuclei of the oculomotor nerve. From these nuclei, the medial longitudinal bundle runs parallel to the midline on both sides.

Rice. 5.9. Damage to the abducens nerve (converging strabismus)

Rice. 5.10. Oculomotor nerves and medial longitudinal bundle.

1 - the nucleus of the oculomotor nerve; 2 - accessory nucleus of the oculomotor nerve (nucleus of Yakubovich-Edinger-Westphal); 3 - posterior central nucleus of the oculomotor nerve (Perlia's nucleus); 4 - ciliary knot; 5 - the nucleus of the trochlear nerve; 6 - the core of the abducens nerve; 7 - own nucleus of the medial longitudinal bundle (Darkshevich's nucleus); 8 - medial longitudinal bundle; 9 - adversive center of the premotor zone of the cerebral cortex; 10 - lateral vestibular nucleus.

Damage syndromes: I - large cell nucleus of the oculomotor nerve;

II - accessory nucleus of the oculomotor nerve; III - nuclei of the IV nerve; IV - nuclei of the VI nerve; V - right adversive field; VI - left bridge center of gaze. Paths that provide friendly movements of the eyeballs are marked in red.

down to the cervical segments of the spinal cord. It unites the nuclei of the motor nerves of the eye muscles and receives impulses from the cervical part of the spinal cord (providing innervation of the posterior and anterior muscles of the neck), from the vestibular nuclei, the reticular formation, the basal nuclei and the cerebral cortex.

The installation of the eyeballs on the object is carried out arbitrarily, but still, most eye movements occur reflexively. If any object enters the field of view, the gaze is involuntarily fixed on it. When an object moves, the eyes involuntarily follow it, while the image of the object is focused at the point of best vision on the retina. When we arbitrarily examine an object of interest to us, our gaze automatically lingers on it, even if we ourselves are moving or the object is moving. Thus, voluntary movements of the eyeballs are based on involuntary reflex movements.

The afferent part of the arc of this reflex is the path from the retina, the visual path to the visual cortex (field 17), from where impulses enter fields 18 and 19. Efferent fibers begin from these fields, which in the temporal region join the visual radiation, following to the contralateral oculomotor centers of the midbrain and pons. From here, the fibers go to the corresponding nuclei of the motor nerves of the eyes, one part of the efferent fibers goes directly to the oculomotor centers, the other makes a loop around field 8.

In the anterior part of the midbrain, there are structures of the reticular formation that regulate certain directions of gaze. The interstitial nucleus, located in the posterior wall of the third ventricle, regulates the movements of the eyeballs upwards, the nucleus in the posterior commissure - downwards; the interstitial nucleus of Cahal and the nucleus of Darkshevich - rotational movements. Horizontal eye movements are provided by the area of ​​the back of the brain bridge, close to the nucleus of the abducens nerve (bridge center of gaze).

The innervation of voluntary movements of the eyeballs is carried out by the cortical center of gaze, located in field 8 in the posterior part of the middle frontal gyrus. From it, fibers go as part of the corticonuclear tract to the internal capsule and legs of the brain, cross and transmit impulses through the neurons of the reticular formation and the medial longitudinal bundle to the nuclei of III, IV, VI pairs of cranial nerves. Thanks to this friendly innervation, combined movements of the eyeballs up, to the sides, down are carried out.

If the cortical center of the gaze or the frontal cortical-nuclear tract is damaged (in the radiant crown, the anterior leg of the internal capsule, the leg of the brain, the anterior part of the pontine tegmentum), the patient cannot arbitrarily divert the eyeballs to the side opposite to the lesion (Fig. 5.11), while they are turned towards the pathological focus (the patient "looks" at the focus and "turns away" from the paralyzed limbs). This is due to the dominance of the cortical center of gaze on the opposite side. With its bilateral defeat, voluntary movements of the eyeballs in both directions are sharply limited. Irritation of the cortical center of gaze is manifested by a friendly movement of the eyeballs in the opposite direction (the patient "turns away" from the focus of irritation).

The defeat of the pontine center of gaze in the region of the posterior part of the pontine tire, close to the nucleus of the abducens nerve, leads to the development of paresis (paralysis) of the gaze towards the pathological focus. In this case, the eyeballs are set in the direction opposite to the focus (the patient "turns away" from the focus, and if the pyramidal path is involved in the process, the gaze is directed to the paralyzed limbs). So, for example, when the right bridging center of gaze is destroyed, the influences of the left bridging center of gaze predominate, and the patient's eyeballs turn to the left. The defeat of the tegmentum of the midbrain at the level of the superior colliculus is accompanied by paralysis of gaze upwards, and paralysis of gaze downwards is less common.

With the defeat of the occipital regions, reflex eye movements disappear. The patient can make arbitrary movements of the eyes in any direction, but is not able to follow the object. The object immediately disappears from the field of best vision and is found using voluntary eye movements.

With damage to the medial longitudinal bundle, internuclear ophthalmoplegia occurs. With unilateral damage to the medial longitudinal bundle, the

Rice. 5.11. Gaze paralysis to the left (installation of eyeballs in the extreme right position)

there is innervation of the ipsilateral (located on the same side) medial rectus muscle, and monocular nystagmus occurs in the contralateral eyeball. Muscle contraction in response to convergence is maintained. The medial longitudinal bundles are located close to each other, so their simultaneous defeat is possible. In this case, the eyeballs cannot be brought inward with horizontal gaze. Monocular nystagmus occurs in the dominant eye. The remaining movements of the eyeballs and the reaction of the pupils to light are preserved.

Research methodology. It is necessary to establish the presence or absence of doubling (diplopia). True diplopia that occurs with binocular vision is due to a violation of the movements of the eyeballs, in contrast to false diplopia, observed with monocular vision and associated with changes in the properties of the refractive media of the eye, psychogenic disorders of perception. Diplopia is a sign sometimes more subtle than an objectively established insufficiency of the function of one or another external muscle of the eye. Diplopia occurs or increases when looking towards the affected muscle. Insufficiency of the lateral and medial rectus muscles causes double vision in the horizontal plane, and other muscles in the vertical or oblique planes.

The width of the palpebral fissures is determined: narrowing with ptosis of the upper eyelid (unilateral, bilateral, symmetrical, asymmetrical); expansion of the palpebral fissure due to the inability to close the eyelids. Possible changes in the position of the eyeballs are assessed: exophthalmos (unilateral, bilateral, symmetrical, asymmetrical), enophthalmos, strabismus (unilateral, bilateral, converging or diverging horizontally, diverging vertically - Hertwig-Magendie symptom).

Evaluate the shape of the pupils (correct - round, incorrect - oval, unevenly elongated, multifaceted or scalloped "corroded" contours); pupil size: moderate miosis (narrowing up to 2 mm), pronounced (up to 1 mm); mydriasis is insignificant (expansion up to 4-5 mm); moderate (6-7 mm), pronounced (more than 8 mm), difference in pupil size (anisocoria). Noticeable sometimes immediately anisocoria and deformation of the pupils are not always associated with the lesion n. oculomotorius(possible congenital features, consequences of eye injury or inflammation, asymmetry of sympathetic innervation, etc.).

It is important to examine the reaction of pupils to light. Both direct and friendly reactions of each pupil are checked separately. The patient's face is turned to the light source, the eyes are open; the examiner, first tightly closing both eyes of the subject with his palms, quickly takes away

eats one of his hands, observing the direct reaction of the pupil to light; the other eye is also examined. Normally, the reaction of pupils to light is lively: at a physiological value of 3-3.5 mm, dimming leads to pupil dilation up to 4-5 mm, and illumination leads to narrowing to 1.5-2 mm. To detect a friendly reaction, one eye of the subject is covered with a palm; in the other open eye, pupil dilation is observed; when the hand is taken away from the closed eye, simultaneous friendly constriction of the pupils occurs in both. The same is done for the other eye. It is convenient to use a flashlight to study light reactions.

In order to study convergence, the doctor asks the patient to look at the malleus, moved back 50 cm and located in the middle. When the hammer approaches the patient's nose, the eyeballs converge and hold them in the convergence position at the fixation point at a distance of 3-5 cm from the nose. The reaction of the pupils to convergence is assessed by the change in their size as the eyeballs approach each other. Normally, constriction of the pupils is observed, reaching a sufficient degree at a distance of the fixation point of 10-15 cm. To study accommodation, one eye is closed, and the other is asked to alternately fix the gaze on distant and nearby objects, assessing the change in the size of the pupil. Normally, when looking into the distance, the pupil expands, when looking at a nearby object, it narrows.

Trigeminal nerve - n. trigeminus (V pair)

The trigeminal nerve is the main sensory nerve of the face and mouth; in addition, it contains motor fibers that innervate the masticatory muscles (Fig. 5.12). The sensitive part of the trigeminal nerve system (Fig. 5.13) is formed by a chain consisting of three neurons. The cells of the first neurons are located in the semilunar node of the trigeminal nerve, located on the anterior surface of the pyramid of the temporal bone between the layers of the dura mater. The dendrites of these cells are sent to the receptors of the skin of the face, as well as the oral mucosa, and the axons in the form of a common root enter the bridge and approach the cells that form the nucleus of the spinal cord of the trigeminal nerve (n. tractus spinalis), providing surface sensitivity.

This nucleus passes through the pons, the medulla oblongata, and the two upper cervical segments of the spinal cord. There is a somatotopic representation in the nucleus, its oral sections are associated with the perioral zone of the face, and the caudal sections are associated with laterally located areas. Neuro-

Rice. 5.12. Trigeminal nerve.

1 - core (lower) of the spinal tract of the trigeminal nerve; 2 - the motor nucleus of the trigeminal nerve; 3 - pontine nucleus of the trigeminal nerve; 4 - the nucleus of the mesencephalic pathway of the trigeminal nerve; 5 - trigeminal nerve; 6 - ophthalmic nerve; 7 - frontal nerve; 8 - nasociliary nerve; 9 - posterior ethmoid nerve; 10 - anterior ethmoid nerve; 11 - lacrimal gland; 12 - supraorbital nerve (lateral branch); 13 - supraorbital nerve (medial branch); 14 - supratrochlear nerve; 15 - subblock nerve; 16 - internal nasal branches; 17 - external nasal branch; 18 - ciliary knot; 19 - lacrimal nerve; 20 - maxillary nerve; 21 - infraorbital nerve; 22 - nasal and upper labial branches of the infraorbital nerve; 23 - anterior upper alveolar branches; 24 - pterygopalatine node; 25 - mandibular nerve; 26 - buccal nerve; 27 - lingual nerve; 28 - submandibular node; 29 - submandibular and sublingual glands; 30 - lower alveolar nerve; 31 - mental nerve; 32 - anterior belly of the digastric muscle; 33 - maxillofacial muscle; 34 - maxillofacial nerve; 35 - chewing muscle; 36 - medial pterygoid muscle; 37 - branches of the drum string; 38 - lateral pterygoid muscle; 39 - ear-temporal nerve; 40 - ear knot; 41 - deep temporal nerves; 42 - temporal muscle; 43 - muscle straining the palatine curtain; 44 - muscle straining the eardrum; 45 - parotid gland. Sensory fibers are indicated in blue, motor fibers in red, and parasympathetic fibers in green.

Rice. 5.13. Sensitive part of the trigeminal nerve.

1 - sensitive areas of the face; 2 - sensory fibers from the area of ​​​​the external auditory canal (penetrate the brain stem as part of VII, IX and X pairs of cranial nerves, enter the nucleus of the spinal cord of the trigeminal nerve); 3 - the nucleus of the spinal tract of the trigeminal nerve; 4 - the nucleus of the mesencephalic pathway of the trigeminal nerve; 5 - trigeminal loop (trigeminal-thalamic path)

nas, conducting impulses of deep and tactile sensitivity, are also located in the semilunar node. Their axons travel to the brainstem and end in the nucleus of the mesencephalic tract of the trigeminal nerve. (nucl. sensibilis n. trigemini), located in the tegmentum of the brain bridge.

The fibers of the second neurons from both sensory nuclei pass to the opposite side and as part of the medial loop (lemniscus medialis) are sent to the thalamus. From the cells of the thalamus, the third neurons of the trigeminal nerve system begin, the axons of which pass through the internal capsule, the radiant crown and go to the cells of the cerebral cortex in the lower sections of the postcentral gyrus (Fig. 5.14).

The sensory fibers of the V pair of cranial nerves are grouped into three branches: the I and II branches are purely motor, the III branch contains motor

Rice. 5.14. Sensitive innervation of the face.

I - segmental type of innervation; II - peripheral type of innervation; 1 - fibers of the V pair of cranial nerves - superficial sensitivity; 2 - spinal nerve fibers (SN); 3 - fibers of the IX and X pairs of cranial nerves; 4 - fibers of the trigeminal nerve - deep sensitivity; 5 - cerebral cortex; 6 - the third neuron; 7 - second neuron; 8 - thalamus

body and sensory fibers. All branches give off bundles of fibers that innervate the dura mater (rr. meningeus).

I branch - ophthalmic nerve(n. ophthalmicus). After exiting the semilunar node, it rises anteriorly and upward and pierces the outer wall of the cavernous sinus, exits the cranial cavity through the superior orbital fissure, located in the supraorbital notch (incisura supraorbitalis) at the medial edge of the upper part of the orbit. The ophthalmic nerve divides into three branches: the nasociliary, lacrimal, and frontal nerves. Provides sensation in the forehead skin, anterior scalp, upper eyelid, inner corner of the eye and back of the nose, mucous membrane of the upper part of the nasal cavity, eye, ethmoid sinus, lacrimal gland, conjunctiva and cornea, dura mater, cerebellar tenon, frontal bone and periosteum.

II branch of the trigeminal nerve - maxillary nerve(n. maxillaris) also perforates the outer wall of the cavernous sinus, exits the cranial cavity through a round hole (f. rotundum) and enters the pterygopalatine fossa, where it gives off three branches - the infraorbital (n. infraorbitalis), zygomatic (n. zygomaticus) and pterygopalatine nerves (nn. pterygopalatini. The main branch - the infraorbital nerve, having passed in the infraorbital canal, exits to the surface of the face through the infraorbital foramen (f. infraorbitalis), innervates the skin of the temporal and zygomatic regions, the lower eyelid and the corner of the eye, the mucous membrane of the posterior lattice cells and the sphenoid sinus, the nasal cavity, the arch of the pharynx, the soft and hard palate, the tonsils, the teeth and the upper jaw. The external branches of the infraorbital nerve have connections with the branches of the facial nerve.

III branch - mandibular nerve(n. mandibularis). The mixed branch is formed by the branches of the sensory and motor roots. It leaves the cranial cavity through a round opening. (f. rotundum) and enters the pterygopalatine fossa. One of the terminal branches is the mental nerve (n. mentalis) comes to the surface of the face through the corresponding opening of the lower jaw (f. mentalis). The mandibular nerve provides sensory innervation to the lower part of the cheek, chin, skin of the lower lip, anterior part of the auricle, external auditory canal, part of the outer surface of the tympanic membrane, buccal mucosa, floor of the mouth, anterior 2/3 tongue, lower jaw, dura mater , as well as motor innervation of masticatory muscles: mm. masseter, temporalis, pterygoideus medialis and lateralis, mylohyoideus, anterior abdomen m. digastricus, m. tensor tympani and m. tensor veli palatini.

The mandibular nerve is connected with the nodes of the autonomic nervous system - with the ear (gangl. oticum), submandibular (gangl. submandibulare), sublingual (gangl. sublinguale). From the nodes go postganglionic parasympathetic secretory fibers to the salivary glands. Together with drum string (chorda tympani) provides taste and surface sensitivity of the tongue.

Research methodology. Find out from the patient whether he experiences pain or other sensations (numbness, crawling) in the face. On palpation of the exit points of the branches of the trigeminal nerve, their soreness is determined. Pain and tactile sensitivity are examined at symmetrical points of the face in the zone of innervation of all three branches, as well as in the zones of Zelder. To assess the functional state of the trigeminal nerve, the state of the conjunctival, root

al, superciliary and mandibular reflexes. Conjunctival and corneal reflexes are examined by lightly touching a strip of paper or a piece of cotton to the conjunctiva or cornea (Fig. 5.15). Normally, the eyelids close at the same time (the arc of the reflex closes through the V and VII nerves), although the conjunctival reflex may be absent in healthy people. The superciliary reflex is caused by a blow of the hammer on the bridge of the nose or the superciliary arch, while the eyelids close. The mandibular reflex is examined by tapping the chin with a hammer with the mouth slightly open: normally, the jaws close as a result of contraction of the masticatory muscles (the arc of the reflex includes sensory and motor fibers of the Vth nerve).

To study the motor function, it is determined whether the displacement of the lower jaw occurs when the mouth is opened. Then the examiner puts his palms on the temporal and chewing muscles in succession and asks the patient to clench and unclench his teeth several times, noting the degree of muscle tension on both sides.

Damage symptoms. Damage to the nucleus of the spinal tract of the trigeminal nerve is manifested by a disorder of surface sensitivity of the segmental type (in the Zelder zones) while maintaining a deep (pressure feeling) vibration. If the caudal parts of the nucleus are affected, anesthesia occurs on the lateral surface of the face, passing from the forehead to the auricle and chin, and if the oral part is affected, the anesthesia strip captures the area of ​​the face located near the midline (forehead, nose, lips).

When the root of the trigeminal nerve is damaged (in the area from the exit from the bridge to the semilunar node), there is a violation of superficial and deep sensitivity in the zone of innervation of all three branches of the trigeminal nerve (peripheral or neuritic type of lesion). Similar symptoms are observed with the defeat of the semilunar node, while herpetic eruptions may appear.

Involvement in the pathological process of individual branches of the trigeminal nerve is manifested by

Rice. 5.15. Inducing the corneal reflex

sensitivity device in the zone of their innervation. If the I branch suffers, the conjunctival, corneal and superciliary reflexes fall out. With the defeat of the III branch, the mandibular reflex falls out, a decrease in taste sensitivity in the anterior 2/3 of the tongue of the corresponding side is possible.

Irritation of the trigeminal nerve or its branches is accompanied by intense paroxysmal pain in the corresponding zone of innervation (trigeminal neuralgia). On the skin of the face, mucous membranes of the nasal and oral cavities, trigger points are detected, touching which causes a pain discharge. Palpation of the exit points of the nerve to the surface of the face is painful.

The branches of the trigeminal nerve anastomose with the facial, glossopharyngeal, and vagus nerves and contain sympathetic fibers. With inflammatory processes in the facial nerve, pain occurs in the corresponding half of the face, most often in the ear area, behind the mastoid process, less often in the forehead, in the upper and lower lips, and the lower jaw. When the glossopharyngeal nerve is irritated, the pain spreads from the root of the tongue to its tip.

The defeat of the motor fibers of the III branch or the motor nucleus leads to the development of paresis or paralysis of the muscles on the side of the focus. There is atrophy of the masticatory and temporal muscles, their weakness, deviation of the lower jaw when opening the mouth towards the paretic muscles. With a bilateral lesion, the lower jaw sags. When the motor neurons of the trigeminal nerve are irritated, tonic tension of the masticatory muscles (trismus) develops. The chewing muscles are so tense that it is impossible to open the jaws. Trismus can occur when the centers of masticatory muscles in the cerebral cortex and the pathways coming from them are irritated. At the same time, food intake is disturbed or completely impossible, speech is disturbed, and there are respiratory disorders. Due to the bilateral cortical innervation of the motor nuclei of the trigeminal nerve, chewing disorders do not occur with unilateral damage to the central neurons.

Facial nerve - n. facialis (VII pair)

The facial nerve (Fig. 5.16) is a mixed nerve. It contains motor, parasympathetic and sensory fibers, the last two types of fibers are isolated as an intermediate nerve.

The motor part of the facial nerve provides innervation to all facial muscles of the face, muscles of the auricle, skull, back

Rice. 5.16. facial nerve.

1 - the core of a single path; 2 - upper salivary nucleus; 3 - the nucleus of the facial nerve; 4 - knee (internal) of the facial nerve; 5 - intermediate nerve; 6 - knee assembly; 7 - deep stony nerve; 8 - internal carotid artery; 9 - pterygo-palatine node; 10 - ear knot; 11 - lingual nerve; 12 - drum string; 13 - stirrup nerve and stirrup muscle; 14 - tympanic plexus; 15 - knee-tympanic nerve; 16 - knee (external) of the facial nerve; 17 - temporal branches; 18 - frontal belly of the occipital-frontal muscle; 19 - muscle wrinkling the eyebrow; 20 - circular muscle of the eyes; 21 - muscle of the proud; 22 - large zygomatic muscle; 23 - small zygomatic muscle; 24 - muscle that raises the upper lip; 25 - muscle that lifts the upper lip and wing of the nose; 26, 27 - nasal muscle; 28 - muscle that raises the corner of the mouth; 29 - muscle that lowers the nasal septum; 30 - upper incisor muscle; 31 - circular muscle of the mouth; 32 - lower incisor muscle; 33 - buccal muscle; 34 - muscle lowering the lower lip; 35 - chin muscle; 36 - muscle that lowers the corner of the mouth; 37 - muscle of laughter; 38 - subcutaneous muscle of the neck; 39 - zygomatic branches; 40 - sublingual gland; 41 - cervical branch; 42 - submandibular node; 43 - posterior ear nerve; 44 - stylohyoid muscle; 45 - posterior belly of the digastric muscle; 46 - stylomastoid opening; 47 - occipital belly of the occipital-frontal muscle; 48 - upper and rear ear muscles. Motor fibers are marked in red, sensory fibers in blue, and parasympathetic fibers in green.

abdomen of the digastric muscle, stapedius muscle and subcutaneous muscle of the neck. The central neurons are represented by the cells of the cortex of the lower third of the precentral gyrus, the axons of which, as part of the corticonuclear pathway, pass the radiant crown, the internal capsule, the brain stems and go to the brain bridge to the nucleus of the facial nerve. The lower part of the nucleus and, accordingly, the lower part of the mimic muscles are connected only with the cortex of the opposite hemisphere, while the upper part of the nucleus (and the upper part of the mimic muscles) has a bilateral cortical representation.

Peripheral motor neurons are located in the nucleus of the facial nerve, located in the bottom of the IV ventricle of the brain. Axons of peripheral neurons form the facial nerve root, which, together with the root of the intermediate nerve, emerges from the pons of the brain between the posterior edge of the pons and the olive of the medulla oblongata. Further, both nerves enter the internal auditory opening and enter the canal of the facial nerve (fallopian canal) of the pyramid of the temporal bone. In the canal, the nerves form a common trunk, making two turns corresponding to the bends of the canal. In the knee of the canal, the knee of the facial nerve is formed, where the node of the knee is located - gangl. geniculi. After the second turn, the nerve is located behind the cavity of the middle ear and exits the canal through the stylomastoid opening, entering the parotid salivary gland. In it, it is divided into 2-5 primary branches, forming the so-called large crow's foot, from where the nerve fibers are sent to the muscles of the face. There are connections of the facial nerve with the trigeminal, glossopharyngeal, superior laryngeal nerves.

In the facial canal, three branches depart from the facial nerve.

Greater stony nerve(n. petrosus major) contains parasympathetic fibers originating in the lacrimal nucleus of the brainstem. The nerve starts directly from the node of the knee, on the outer base of the skull it connects with the deep petrosal nerve (a branch of the sympathetic plexus of the internal carotid artery) and forms the nerve of the pterygoid canal, which enters the pterygopalatine canal and reaches the pterygopalatine node. The large stony nerve innervates the lacrimal gland. After a break in the pterygopalatine ganglion, the fibers go as part of the maxillary and further zygomatic nerves, anastomose with the lacrimal nerve (a branch of the trigeminal nerve), innervating the lacrimal gland.

Stapes nerve(n. stepedius) enters the tympanic cavity and innervates the stapedius muscle. With the tension of this muscle, conditions are created for the best audibility.

drum string(chorda tympani) contains sensitive (gustatory) and vegetative fibers. Sensitive cells are located in the nucleus of a solitary pathway (n. tractus solitarius) brain stem (common with the glossopharyngeal nerve), vegetative - in the upper salivary nucleus. The tympanic string separates from the facial nerve in the lower part of the facial canal, enters the tympanic cavity and exits through the stony-tympanic fissure to the base of the skull. Sensitive fibers, combined with the lingual nerve (a branch of the trigeminal nerve), provide taste sensitivity in the anterior 2/3 of the tongue. Secretory salivary fibers are interrupted in the submandibular and sublingual parasympathetic nodes and provide innervation to the submandibular and sublingual salivary glands.

Research methodology. Basically determine the state of innervation of the mimic muscles of the face. The symmetry of the frontal folds, palpebral fissures, the severity of the nasolabial folds and the corners of the mouth are assessed. Functional tests are used: the patient is asked to wrinkle his forehead, bare his teeth, puff out his cheeks, whistle; when performing these actions, weakness of the mimic muscles is revealed. To clarify the nature and severity of paresis, electromyography and electroneurography are used.

Taste sensitivity is examined in the anterior 2/3 of the tongue, usually for sweet and sour, for which a drop of a solution of sugar or lemon juice is applied to each half of the tongue with a glass rod (pipette, piece of paper). After each test, the patient should rinse their mouth well with water.

Damage symptoms. With damage to the motor part of the facial nerve, peripheral paralysis of the facial muscles (prosoplegia) develops (Fig. 5.17). The entire affected half of the face is immobile, mask-like, the folds of the forehead and nasolabial fold are smoothed, the palpebral fissure is expanded, the eye does not close (lagophthalmos - hare's eye), the corner of the mouth is lowered. When trying to close the eye, the eyeball turns upward (Bell's phenomenon). The frequency of spontaneous blinking on the side of the paresis is less. With closed eyes on the affected side, the vibration of the eyelids is reduced or absent, which is determined by a light touch of the fingers on the closed eyelids at the outer corners of the eye. A symptom of eyelashes is revealed: due to moderately pronounced paresis with the eyes closed as much as possible, the eyelashes on the side of the lesion are better seen than on the healthy one (due to insufficient closure of the circular muscle of the eye).

Rice. 5.17. Peripheral left facial nerve lesion

As a result of paralysis of the circular muscle of the eye and insufficient fit of the lower eyelid to the eyeball, a capillary gap is not formed between the lower eyelid and the mucous membrane of the eye, which makes it difficult for the tear to move to the lacrimal canal and may be accompanied by lacrimation. Constant irritation of the conjunctiva and cornea with airflow and dust leads to the development of inflammatory phenomena - conjunctivitis and keratitis.

The clinical picture of damage to the facial nerve may vary depending on the localization of the pathological process. When the motor nucleus of the facial nerve is damaged (for example, with the bridge form of poliomyelitis), isolated paralysis of the facial muscles occurs. With a significant volume of the pathological focus, the adjacent pyramidal path may be involved in the process. In addition to paralysis of the mimic muscles, there is a central paralysis (paresis) of the limbs of the opposite side (Miyar-Gubler syndrome). With simultaneous damage to the nucleus of the abducens nerve, convergent strabismus also occurs on the side of the lesion or gaze paralysis towards the focus (Fauville's syndrome). If at the same time sensory pathways at the level of the nucleus suffer, then hemianesthesia develops on the opposite side.

The defeat of the large stony nerve is accompanied by a violation of lacrimation, which leads to dryness of the membranes of the eyeball (xerophthalmia). In severe cases of impaired tear secretion, episcleritis and keratitis may develop. Irritation of the large stony nerve is accompanied by excessive lacrimation. When the function of the stapedial nerve is impaired, paralysis of the stapedial muscle occurs, as a result of which the perception of all sounds becomes sharp, causing painful, unpleasant sensations (hyperacusia). Due to damage to the drum string, taste sensitivity is lost (ageusia) or reduced (hypogeusia). Much less often

there are hypergeusia - an increase in taste sensitivity or parageusia - its perversion.

The pathological process in the region of the cerebellopontine angle, where the facial nerve exits the brain stem, is manifested by prosoplegia in combination with symptoms of auditory damage (hearing loss or deafness) and trigeminal nerves. Such a clinical picture is observed with acoustic neuroma, with inflammatory processes in this area (arachnoiditis of the cerebellopontine angle). In connection with the violation of the conduction of impulses along the fibers of the intermediate nerve, dry eyes (xerophthalmia) occur, taste sensitivity is lost in the anterior 2/3 of the tongue on the side of the lesion. In this case, xerostomia (dryness in the oral cavity) should develop, but due to the fact that other salivary glands usually function, dryness in the oral cavity is not noted. There is also no hyperacusis, which theoretically should be, but due to a combined lesion of the auditory nerve, it is not detected.

Damage to the nerve in the facial canal up to its knee above the origin of the large stony nerve leads, along with mimic paralysis, to dryness of the mucous membranes of the eye, decreased taste and hyperacusis. If the nerve is affected after the departure of the large stony and stapedial nerves, but above the discharge of the tympanic string, then prosoplegia, lacrimation and taste disorders are determined. If the VII pair is damaged in the bone canal below the discharge of the tympanic string or when exiting the stylomastoid foramen, only mimic paralysis occurs with lacrimation (due to irritation of the mucous membranes of the eye with incomplete closure of the eyelids).

With damage to the cortical-nuclear pathway, which carries fibers from the motor cortex to the motor nucleus of the facial nerve, paralysis of the facial muscles occurs only in the lower half of the face on the side opposite to the lesion. Smoothness of the nasolabial folds, grin disturbances, puffing of the cheeks are revealed with the ability to close the eyes and wrinkle the forehead. Hemiplegia (or hemiparesis) often occurs on this side.

Vestibulocochlear nerve - n. vestibulocochlearis (VIII pair)

The vestibulocochlear nerve consists of two roots: lower - cochlear and upper - vestibular (Fig. 5.18). Combines two functionally different parts.

Rice. 5.18. Vestibulocochlear nerve.

1 - olive; 2 - trapezoid body; 3 - vestibular nuclei; 4 - posterior cochlear nucleus; 5 - anterior cochlear nucleus; 6 - vestibular root; 7 - cochlear root; 8 - internal auditory opening; 9 - intermediate nerve; 10 - facial nerve; 11 - knee assembly; 12 - cochlear part; 13 - vestibule; 14 - vestibular node; 15 - anterior membranous ampulla; 16 - lateral membranous ampulla; 17 - elliptical bag; 18 - posterior membranous ampulla; 19 - spherical bag; 20 - cochlear duct

cochlear part(pars cochlearis). This part, as a purely sensitive, auditory, originates from the spiral knot (gangl. spirale cochleae), the labyrinth lying in the cochlea (Fig. 5.19). The dendrites of the cells of this node go to the hair cells of the spiral (Corti) organ, which are auditory receptors. The axons of the ganglion cells go in the internal auditory canal along with the vestibular part of the nerve and for a short distance from porus acusticus internus- next to the facial nerve. After leaving the pyramid of the temporal bone, the nerve enters the brain stem in the region of the upper part of the medulla oblongata and the lower part of the bridge. The fibers of the cochlear part end in the anterior and posterior cochlear nuclei. Most of the axons of the neurons of the anterior nucleus pass to the opposite side of the bridge and end in the superior olive and trapezoid body, a smaller part approaches the same formations of its side. The axons of the cells of the superior olive and nucleus of the trapezoid body form a lateral loop that rises up and ends in the inferior tubercle of the roof of the midbrain and in the medial geniculate body. The posterior nucleus sends fibers as part of the so-called auditory strips, which run along the bottom of the IV ventricle to the median line.

Rice. 5.19. Cochlear part of the vestibulocochlear tract. Pathways of the auditory analyzer. 1 - fibers coming from cochlear receptors; 2 - cochlear (spiral) node; 3 - posterior cochlear nucleus; 4 - anterior cochlear nucleus; 5 - upper olive core; 6 - trapezoid body; 7 - brain strips; 8 - lower cerebellar peduncle; 9 - superior cerebellar peduncle; 10 - middle cerebellar peduncle; 11 - branches to the cerebellar vermis; 12 - reticular formation; 13 - lateral loop; 14 - lower tubercle; 15 - pineal body; 16 - upper tubercle; 17 - medial geniculate body; 18 - cerebral cortex (superior temporal gyrus)

nii, where they plunge deep and go to the opposite side, join the lateral loop, together with which they rise up and end in the lower tubercle of the roof of the midbrain. Part of the fibers from the posterior nucleus is sent to the lateral loop of its side. From the cells of the medial geniculate body, axons pass as part of the posterior leg of the internal capsule and terminate in the cerebral cortex, in the middle part of the superior temporal gyrus (Geshl's gyrus). It is important that auditory receptors are associated with the cortical representation of both hemispheres.

Research methodology. By questioning, they find out if the patient has a hearing loss or, conversely, an increase in the perception of sounds, ringing, tinnitus, auditory hallucinations. For an approximate assessment of hearing, they whisper words that are normally perceived from a distance of 6 m. Each ear is examined in turn. More accurate information is provided by instrumental research (audiometry, registration of acoustic evoked potentials).

Damage symptoms. Due to the repeated intersection of the auditory conductors, both peripheral sound-receiving apparatuses are connected with both hemispheres of the brain, therefore, damage to the auditory conductors above the anterior and posterior auditory nuclei does not cause auditory prolapse.

With damage to the receptor auditory apparatus, the cochlear part of the nerve and its nuclei, hearing loss (hypacusia) or its complete loss (anacusia) is possible. In this case, symptoms of irritation (sensation of noise, whistling, buzzing, cod, etc.) can be observed. The lesion can be either unilateral or bilateral. When the cortex of the temporal lobe of the brain is irritated (for example, with tumors), auditory hallucinations may occur.

vestibulum (pars vestibularis)

The first neurons (Fig. 5.20) are located in the vestibule node, located in the depths of the internal auditory canal. The dendrites of the node cells end with receptors in the labyrinth: in the ampullae of the semicircular canals and in two membranous sacs. The axons of the cells of the vestibular node form the vestibular part of the nerve, which leaves the temporal bone through the internal auditory opening, enters the brainstem in the cerebellopontine angle and ends in 4 vestibular nuclei (second neurons). The vestibular nuclei are located in the lateral part of the bottom of the IV ventricle - from the lower part of the bridge to the middle of the medulla oblongata. These are the lateral (Deiters), medial (Schwalbe), superior (Bekhterev) and inferior (Roller) vestibular nuclei.

From the cells of the lateral vestibular nucleus, the predvernospinal path begins, which on its side, as part of the anterior funiculus of the spinal cord, approaches the cells of the anterior horns. Bekhterev's, Schwalbe's and Roller's nuclei have connections with the medial longitudinal bundle, due to which the connection between the vestibular analyzer and the gaze innervation system is carried out. Through the nuclei of Bekhterev and Schwalbe, connections are made between the vestibular apparatus and the cerebellum. In addition, there are connections between the vestibular nuclei and the reticular formation of the brain stem, the posterior nucleus of the vagus nerve. The axons of neurons of the vestibular nuclei transmit impulses to the thalamus, the extrapyramidal system and terminate in the cortex of the temporal lobes of the large brain near the auditory projection zone.

Research methodology. When examining the vestibular apparatus, they find out if the patient has dizziness, how the change in head position, standing up affect dizziness. To identify nystagmus in a patient, his gaze is fixed on the malleus and the malleus is moved to the sides or up and down. To study the vestibular apparatus, a rotational test on a special chair, a caloric test, etc. are used.

Rice. 5.20. The vestibular part of the vestibulocochlear nerve. The pathways of the vestibular analyzer: 1 - vestibulo-spinal path; 2 - semicircular ducts; 3 - vestibular node; 4 - vestibular root; 5 - lower vestibular nucleus; 6 - medial vestibular nucleus; 7 - lateral vestibular nucleus; 8 - upper vestibular nucleus; 9 - the core of the tent of the cerebellum; 10 - dentate nucleus of the cerebellum;

11 - medial longitudinal bundle;

12 - the core of the abducens nerve; 13 - reticular formation; 14 - superior cerebellar peduncle; 15 - red core; 16 - the nucleus of the oculomotor nerve; 17- Darkshevich's core; 18 - lenticular core; 19 - thalamus; 20 - cerebral cortex (parietal lobe); 21 - cerebral cortex (temporal lobe)

Damage symptoms. The defeat of the vestibular apparatus: the labyrinth, the vestibular part of the VIII nerve and its nuclei - leads to the appearance of dizziness, nystagmus and impaired coordination of movements. With dizziness, the patient has a false sensation of displacement or rotation of his own body and surrounding objects. Often, dizziness occurs paroxysmal, reaches a very strong degree, may be accompanied by nausea, vomiting. During severe dizziness, the patient lies with his eyes closed, afraid to move, since even a slight movement of the head increases dizziness. It should be remembered that patients often describe various sensations under dizziness, so it is necessary to find out whether there is systemic (vestibular) or non-systemic dizziness in the form of a feeling of sinking, instability, close to fainting and, as a rule, not associated with damage to the vestibular analyzer.

Nystagmus in the pathology of the vestibular analyzer is usually detected when looking to the side, rarely nystagmus is expressed when looking directly, both eyeballs are involved in movements, although monocular nystagmus is also possible.

Depending on the direction, horizontal, rotatory and vertical nystagmus are distinguished. Irritation of the vestibular part of the VIII nerve and its nuclei causes nystagmus in the same direction. Switching off the vestibular apparatus leads to nystagmus in the opposite direction.

The defeat of the vestibular apparatus is accompanied by discoordination of movements (vestibular ataxia), a decrease in muscle tone. The gait becomes shaky, the patient deviates towards the affected labyrinth. In this direction, he often falls.

Glossopharyngeal nerve - n. glossopharyngeus (IX pair)

The glossopharyngeal nerve contains four types of fibers: sensory, motor, gustatory and secretory (Fig. 5.21). They leave the cranial cavity as part of a common trunk through the jugular foramen (f jugulare). The sensitive part of the glossopharyngeal nerve, which provides pain sensitivity, includes a chain of three neurons. The cells of the first neurons are located in the upper and lower nodes of the glossopharyngeal nerve, located in the region of the jugular foramen. The dendrites of these cells are sent to the periphery, where they end at the receptors of the posterior third of the tongue, soft palate, pharynx, pharynx, anterior surface of the epiglottis, auditory tube and tympanic cavity, and the axons enter the medulla oblongata in the posterolateral groove behind the olive, where they end in n. sensorius. The axons of the second neurons located in the nucleus pass to the opposite side, take an upward direction, join the fibers of the second neurons of the common sensory pathways, and together with them end in the thalamus. The axons of the third neurons originate in the cells of the thalamus, pass through the posterior third of the posterior pedicle of the internal capsule, and go to the cortex of the lower postcentral gyrus.

Sensitive fibers of the glossopharyngeal nerve, which conduct taste sensations from the posterior third of the tongue, are dendrites of the cells of the lower node of this nerve, the axons of which enter the nucleus of the solitary pathway (common with the tympanic string). From the nucleus of the solitary pathway, the second neuron begins, the axon of which forms a cross, being part of the medial loop, and ends in the ventral and medial nuclei of the thalamus. From the nuclei of the thalamus originate the fibers of the third neuron, which transmit taste information to the cortex of the cerebral hemispheres. (operculum temporale gyri parahippocampalis).

Rice. 5.21. Glossopharyngeal nerve.

I - the core of a single path; 2 - double core; 3 - lower salivary nucleus; 4 - jugular opening; 5 - upper node of the glossopharyngeal nerve; 6 - the lower node of this nerve; 7 - connecting branch with the ear branch of the vagus nerve; 8 - the lower node of the vagus nerve; 9 - upper cervical sympathetic node; 10 - bodies of the carotid sinus; II - carotid sinus and plexus; 12 - common carotid artery; 13 - sinus branch; 14 - tympanic nerve; 15 - facial nerve; 16 - knee-tympanic nerve; 17 - large stony nerve; 18 - pterygopalatine node; 19 - ear knot; 20 - parotid gland; 21 - small stony nerve; 22 - auditory tube; 23 - deep stony nerve; 24 - internal carotid artery; 25 - carotid-tympanic nerves; 26 - styloid muscle; 27 - connecting branch with the facial nerve; 28 - stylo-pharyngeal muscle; 29 - sympathetic vasomotor branches; 30 - motor branches of the vagus nerve; 31 - pharyngeal plexus; 32 - fibers to the muscles and mucous membrane of the pharynx and soft palate; 33 - sensitive branches to the soft palate and tonsils; 34 - taste and sensory fibers to the posterior third of the tongue; VII, IX, X - cranial nerves. Motor fibers are marked in red, sensory fibers in blue, parasympathetic in green, sympathetic in purple

The motor path of the IX pair consists of two neurons. The first neuron is represented by the cells of the lower part of the precentral gyrus, the axons of which pass as part of the cortical-nuclear pathways and end at the double nucleus of their own and opposite sides. From the double nucleus (second neuron), in common with the vagus nerve, fibers depart that innervate the stylo-pharyngeal muscle, which raises the upper part of the pharynx during swallowing.

Parasympathetic fibers start from the anterior hypothalamus and end at the lower salivary nucleus (common with the large stony nerve), from which the fibers in the glossopharyngeal nerve pass into one of its large branches - the tympanic nerve, forming the tympanic nerve plexus in the tympanic cavity together with the sympathetic branches . Further, the fibers enter the ear node, and the postganglionic fibers go as part of the connecting branch to the ear-temporal nerve and innervate the parotid gland.

Damage symptoms. When the glossopharyngeal nerve is affected, taste disorders are observed in the posterior third of the tongue (hypogeusia or ageusia), loss of sensitivity in the upper half of the pharynx. Motor function disorders are not clinically expressed due to the insignificant functional role of the stylo-pharyngeal muscle. Irritation of the cortical projection area in the deep structures of the temporal lobe leads to the appearance of false taste sensations (parageusia). Sometimes they can be harbingers of an epileptic seizure (aura). Irritation of the IX nerve causes pain in the root of the tongue or tonsil, spreading to the palatine curtain, throat, ear canal.

Nervus vagus - n. vagus (X pair)

The vagus nerve contains sensory, motor and autonomic fibers (Fig. 5.22), exits the cranial cavity through the jugular foramen (f. jugulare). The first neurons of the sensitive part are represented by pseudo-unipolar cells, clusters of which form the upper and lower nodes of the vagus nerve, located in the region of the jugular foramen. The dendrites of these pseudo-unipolar cells are sent to the periphery and end at the receptors of the dura mater of the posterior cranial fossa, the posterior wall of the external auditory canal and part of the skin of the auricle, the mucous membrane of the pharynx, larynx, upper trachea and internal organs. Central processes of pseudounipolar

Rice. 5.22. Nervus vagus.

1 - the core of a single path; 2 - the nucleus of the spinal tract of the trigeminal nerve; 3 - double core; 4 - posterior nucleus of the vagus nerve; 5 - spinal roots of the accessory nerve; 6 - meningeal branch (to the posterior cranial fossa); 7 - ear branch (to the posterior surface of the auricle and to the external auditory canal); 8 - upper cervical sympathetic node; 9 - pharyngeal plexus; 10 - muscle that raises the palatine curtain; II - tongue muscle; 12 - palatopharyngeal muscle; 13 - palatine-lingual muscle; 14 - tubal-pharyngeal muscle; 15 - upper constrictor of the pharynx; 16 - sensitive branches to the mucous membrane of the lower part of the pharynx; 17 - upper laryngeal nerve; 18 - sternocleidomastoid muscle; 19 - trapezius muscle; 20 - lower laryngeal nerve; 21 - lower constrictor of the pharynx; 22 - cricoid muscle; 23 - arytenoid muscles; 24 - thyroid arytenoid muscle; 25 - lateral cricoarytenoid muscle; 26 - posterior cricoarytenoid muscle; 27 - esophagus; 28 - right subclavian artery; 29 - recurrent laryngeal nerve; 30 - thoracic cardiac nerves; 31 - cardiac plexus; 32 - left vagus nerve; 33 - aortic arch; 34 - diaphragm; 35 - esophageal plexus; 36 - celiac plexus; 37 - liver; 38 - gallbladder; 39 - right kidney; 40 - small intestine; 41 - left kidney; 42 - pancreas; 43 - spleen; 44 - stomach; VII, IX, X, XI, XII - cranial nerves. Motor fibers are marked in red, sensory fibers in blue, and parasympathetic fibers in green.

cells are sent to the medulla oblongata to the sensitive nucleus of the solitary pathway and are interrupted in it (the second neuron). The axons of the second neuron terminate in the thalamus (the third neuron). From the thalamus through the internal capsule, the fibers are sent to the cortex of the postcentral gyrus.

Motor fibers (the first neuron) go from the cortex of the precentral gyrus to the double nucleus (n. ambiguous) both sides. In the nucleus there are cells of the second neurons, the axons of which are directed to the striated muscles of the pharynx, soft palate, larynx, epiglottis and upper esophagus.

Autonomic (parasympathetic) fibers start from the nuclei of the anterior hypothalamus and go to the autonomic dorsal nucleus, and from it to the heart muscle, smooth muscle tissue of blood vessels and internal organs. Impulses traveling through these fibers slow down the heartbeat, dilate blood vessels, constrict the bronchi, and increase intestinal motility. Postganglionic sympathetic fibers from the cells of the paravertebral sympathetic nodes also enter the vagus nerve and spread along the branches of the vagus nerve to the heart, blood vessels and internal organs.

Research methodology. The IX and X pairs of cranial nerves have separate common nuclei that are embedded in the medulla oblongata, so they are examined simultaneously.

Determine the sonority of the voice (phonation), which may be weakened (dysphonia) or completely absent (aphonia); at the same time, the purity of the pronunciation of sounds (articulation) is checked. They examine the palate and uvula, determine whether there is a drooping of the soft palate, whether the uvula is symmetrically located. To determine the contraction of the soft palate, the subject is asked to pronounce the sound "e" with his mouth wide open. By touching the palatine curtain and the posterior wall of the pharynx with a spatula, one can examine the palatine and pharyngeal reflexes. It should be borne in mind that a bilateral decrease in reflexes can occur normally. Their decrease or absence, on the one hand, is an indicator of the defeat of IX and X pairs. To assess swallowing function, they are asked to take a sip of water. In violation of swallowing (dysphagia), the patient chokes at the first sip. Examine the sensation of taste in the back third of the tongue. With the defeat of the IX pair, the sensation of bitter and salty in the posterior third of the tongue is lost, as well as the sensitivity of the mucous membrane of the upper pharynx. To determine the condition of the vocal cords, laryngoscopy is used.

Damage symptoms. With damage to the peripheral motor neuron of the nerve, swallowing is disturbed due to paralysis of the muscles of the pharynx and esophagus. Liquid food enters the nose as a result of paralysis of the palatine muscles (dysphagia), the main effect of which normally is to separate the nasal cavity and oral cavity and pharynx. Inspection of the pharynx allows you to establish the drooping of the soft palate on the affected side, which determines the nasal tone of the voice. An equally common symptom should be considered paralysis of the vocal cords, causing dysphonia - the voice becomes hoarse. With bilateral damage, aphonia and suffocation are possible. Speech becomes slurred, unintelligible (dysarthria). The symptoms of damage to the vagus nerve include a disorder of the heart: an acceleration of the pulse (tachycardia) and, conversely, when it is irritated, a slowing of the pulse (bradycardia). It should be noted that with a unilateral lesion of the vagus nerve, these disorders are often mildly expressed. Bilateral damage to the vagus nerve leads to severe disorders of swallowing, phonation, respiration and cardiac activity. If sensitive branches of the vagus nerve are involved in the process, there is a disorder in the sensitivity of the mucous membrane of the larynx and pain in it, as well as pain in the ear.

Accessory nerve - n. accessorius (XI pair)

The accessory nerve is motor (Fig. 5.23), it is composed of the vagus and spinal parts. The motor pathway consists of two neurons - central and peripheral. The cells of the central neuron are located in the lower part of the precentral gyrus. Their axons pass through the posterior femur of the internal capsule near the knee, enter the brain stem, bridge, medulla oblongata, where a smaller part of the fibers ends in the caudal part of the motor double nucleus of the vagus nerve. Most of the fibers descend into the spinal cord, ending in the dorsolateral part of the anterior horns at the level of C I -C V of its own and opposite sides, i.e. the nuclei of the accessory nerve have bilateral cortical innervation. A peripheral neuron consists of a dorsal part that emerges from the spinal cord and a vagus part that emerges from the medulla oblongata. The fibers of the spinal part come out of the cells of the anterior horns at the level of the C I -C IV segments, are folded into a common trunk, which through the foramen magnum

penetrates into the cranial cavity, where it connects with the cranial roots from the caudal part of the double nucleus of the vagus nerve, together making up the trunk of the accessory nerve. After leaving the cranial cavity through the jugular foramen, the accessory nerve divides into two branches: the internal, which passes into the trunk of the vagus nerve, and then into the lower laryngeal nerve and the external, which innervates the sternocleidomastoid and trapezius muscles.

Research methodology. After examination and palpation of the muscles innervated by the accessory nerve, the patient is asked to turn his head first to one side and then to the other, raise his shoulders and arm above the horizontal level, and bring the shoulder blades together. To identify muscle paresis, the examiner resists these movements. For this purpose, the patient's head is held by the chin, and the examiner puts his hands on his shoulders. While lifting the shoulders, the examiner holds them with an effort.

Damage symptoms. With a unilateral lesion of the accessory nerve, the head is deviated to the affected side. Turning the head to the healthy side is sharply limited, raising the shoulders (shrugs) is difficult. In addition, there is atrophy of the sternocleidomastoid and trapezius muscles. With bilateral damage to the accessory nerve, the head is tilted back, while turning the head to the right or left is impossible. Unilateral supranuclear lesion is usually not clinically manifested due to bilateral corticonuclear connections. In case of irritation of the XI pair

Rice. 5.23. accessory nerve. 1 - spinal roots (spinal part); 2 - cranial roots (wandering part); 3 - accessory nerve trunk; 4 - jugular opening; 5 - the inner part of the accessory nerve; 6 - the lower node of the vagus nerve; 7 - outer branch; 8 - sternocleidomastoid muscle; 9 - trapezius muscle. Motor fibers are marked in red, sensory fibers in blue, vegetative fibers in green

Rice. 5.24. Hypoglossal nerve.

1 - the nucleus of the hypoglossal nerve; 2 - sublingual canal; 3 - sensitive fibers to the meninges; 4 - connecting fibers to the upper cervical sympathetic ganglion; 5 - connecting fibers to the lower node of the vagus nerve; 6 - upper cervical sympathetic node; 7 - the lower node of the vagus nerve; 8 - connecting fibers to the first two spinal nodes; 9 - internal carotid artery; 10 - internal jugular vein; 11 - awl-lingual muscle; 12 - vertical muscle of the tongue; 13 - upper longitudinal muscle of the tongue; 14 - transverse muscle of the tongue; 15 - lower longitudinal muscle of the tongue; 16 - genio-lingual muscle; 17 - chin-hyoid muscle; 18 - hyoid-lingual muscle; 19 - thyroid muscle; 20 - sternohyoid muscle; 21 - sternothyroid muscle; 22 - upper abdomen of the scapular-hyoid muscle; 23 - lower belly of the scapular-hyoid muscle; 24 - neck loop; 25 - bottom spine; 26 - top spine. Fibers from the bulbar region are marked in red, fibers from the cervical

there is a tonic spasm of the muscles innervated by this nerve. Spastic torticollis develops: the head is turned towards the affected muscle. With bilateral clonic convulsions of the sternocleidomastoid muscle, hyperkinesis appears with nodding movements of the head.

hypoglossal nerve - n. hypoglossus (XII pair)

The hypoglossal nerve is predominantly motor (Fig. 5.24). It contains branches from the lingual nerve, which have sensory fibers. The motor pathway consists of two neurons. The central neuron begins in the cells of the lower third of the precentral gyrus. The fibers leaving these cells pass through the knee of the internal capsule, the bridge and the medulla oblongata, where they end in the nucleus of the opposite side. The peripheral neuron originates from the nucleus of the hypoglossal nerve, which is located in the medulla oblongata dorsally on both sides of the midline, at the bottom of the rhomboid fossa. Fibers from the cells of this nucleus are directed into the thickness of the medulla oblongata in the ventral direction and exit the medulla oblongata between the pyramid and the olive. It exits the cranial cavity through the foramen of the hypoglossal nerve. (f. nervi hypoglossi). The function of the hypoglossal nerve is the innervation of the muscles of the tongue itself and the muscles that move the tongue forward and down, up and back. Of all these muscles for clinical practice, the geniolingual, which pushes the tongue forward and down, is of particular importance. The hypoglossal nerve has connections with the superior sympathetic ganglion and the inferior vagus ganglion.

Research methodology. The patient is offered to stick out his tongue and at the same time they monitor if he deviates to the side, note if there is atrophy, fibrillar twitching, tremor. At the nucleus of the XII pair there are cells from which fibers come that innervate the circular muscle of the mouth, therefore, with a nuclear lesion of the XII pair, thinning, wrinkling of the lips occurs; the patient cannot whistle.

Damage symptoms. If the nucleus or fibers emanating from it are damaged, peripheral paralysis or paresis of the corresponding half of the tongue occurs (Fig. 5.25). The tone and trophism of the muscles decrease, the surface of the tongue becomes uneven, wrinkled. If the cells of the nucleus are damaged, fibrillar twitches appear. When protruding, the tongue deviates towards the affected muscle due to the fact that

Rice. 5.25. Lesion of the left hypoglossal nerve in the central type

Rice. 5.26. Peripheral left hypoglossal nerve lesion

that the geniolingual muscle of the healthy side pushes the tongue forward and medially. With bilateral damage to the hypoglossal nerve, paralysis of the tongue (glossoplegia) develops, while the tongue is motionless, speech is indistinct (dysarthria) or becomes impossible (anarthria). The formation and movement of the food bolus is difficult, which disrupts food intake.

It is very important to differentiate the central and peripheral paralysis of the muscles of the tongue. Central paralysis of the muscles of the tongue occurs when the cortical-nuclear pathway is damaged. With central paralysis, the tongue deviates in the direction opposite to the lesion (Fig. 5.26). Usually, there is paresis (paralysis) of the muscles of the limbs, also opposite to the lesion. With peripheral paralysis, the tongue deviates towards the lesion, there is atrophy of the muscles of half of the tongue, and fibrillar twitches in the case of a nuclear lesion.

5.2. Bulbar and pseudobulbar syndromes

The combined defeat of the peripheral motor neurons of the glossopharyngeal, vagus and hypoglossal nerves in the peripheral type leads to the development of the so-called bulbar palsy. It occurs when the nuclei of the IX, X and XII pairs of cranial nerves are damaged in the medulla oblongata or their roots on the basis of the brain or the nerves themselves. The lesion can be either unilateral or bilateral. There is paralysis of the soft palate, epiglottis, larynx. The voice acquires a nasal tone, becomes deaf and hoarse (dysphonia), speech becomes slurred (dysarthria) or impossible (anartria), swallowing is disturbed: liquid food enters the nose, larynx (dysphagia). On examination, immobility of the palatine arches and vocal cords, fibrillar twitching of the muscles of the tongue, their atrophy are revealed; the mobility of the tongue is limited up to glossoplegia. In severe cases, violations of the vital functions of the body are observed, there are no pharyngeal and palatine reflexes (respiration and cardiac activity). It is observed in amyotrophic lateral sclerosis, circulatory disorders in the medulla oblongata, brainstem tumors, stem encephalitis, syringobulbia, polioencephalomyelitis, polyneuritis, anomalies of the foramen magnum, skull base fracture.

Bilateral damage to the cortical-nuclear pathways connecting the cerebral cortex with the corresponding nuclei of the cranial nerves is called the pseudobulbar syndrome and is accompanied by disorders of swallowing, phonation and articulation. With a unilateral lesion of the supranuclear pathways, no dysfunction of the glossopharyngeal and vagus nerves occurs due to the bilateral cortical connection of their nuclei. Pseudobulbar syndrome, being a central paralysis, does not lead to a loss of stem reflexes associated with the medulla oblongata, in contrast to the bulbar syndrome.

As with any central paralysis, there is no muscle atrophy and changes in electrical excitability. In addition to dysphagia, dysarthria, reflexes of oral automatism are expressed: nasolabial (Fig. 5.27), labial (Fig. 5.28), proboscis (Fig. 5.29), Marinescu-Radovici palmar-chin (Fig. 5.30), as well as violent crying and laughter (Fig. 5.31). An increase in the chin and pharyngeal reflexes is noted.

Rice. 5.27. Nasolabial reflex

Rice. 5.28. lip reflex

Rice. 5.29. proboscis reflex

Rice. 5.30. Marinescu-Radovici Palmar-Chin Reflex

5.3. Alternating syndromes in lesions of the brain stem

The alternating syndrome includes damage to the cranial nerves on the side of the focus according to the peripheral type as a result of the involvement of their nuclei and roots in the process, as well as hemiplegia, often in combination with hemianesthesia of the extremities opposite to the focus. The syndrome occurs as a result of a combined lesion of the pyramidal tract and sensory conductors, as well as the nuclei or roots of the cranial nerves. The functions of the cranial nerves are disturbed on the side of the lesion, and the conduction

Rice. 5.31. Violent crying (a) and laughter (b)

vye frustration come to light on opposite. According to the localization of the lesion in the brain stem, alternating syndromes are divided into peduncular (with damage to the brain stem); pontine, or bridge (with damage to the bridge of the brain); bulbar (with damage to the medulla oblongata).

Peduncular alternating syndromes(Fig. 5.32). Weber syndrome- damage to the oculomotor nerve on the side of the focus and central paresis of the muscles of the face and tongue (lesion of the cortical-nuclear pathway) on the opposite side. Benedict syndrome occurs when localized in the medial-dorsal part of the midbrain, manifested by damage to the oculomotor nerve on the side of the focus, choreoathetosis and intentional trembling of opposite limbs. Claude syndrome manifested by damage to the oculomotor nerve on the side of the focus and cerebellar symptoms (ataxia, adiadochokinesis, dysmetria) on the opposite side. Sometimes dysarthria and swallowing disorder are noted.

Pontine (bridge) alternating syndromes(Fig. 5.33). Miylard-Gubler syndrome occurs when the lower part of the bridge is damaged. This is a peripheral lesion of the facial nerve on the side of the focus, central paralysis of opposite limbs. Brissot-Sicard syndrome is detected when cells of the nucleus of the facial nerve are irritated in the form of a contraction of facial muscles on the side of the focus and spastic hemiparesis or hemiplegia of opposite limbs. Fauville syndrome including

Rice. 5.32. The location of the main cellular formations on a transverse section of the midbrain at the level of the superior colliculus of the quadrigemina (scheme).

1 - upper tubercle; 2 - the nucleus of the oculomotor nerve; 3 - medial loop; 4 - red core; 5 - black substance; 6 - leg of the brain; 7 - oculomotor nerve; localization of the lesion in Weber (8), Benedict (9), Parino (10) syndromes

Rice. 5.33. The location of the nuclei of the cranial nerves on a transverse section in the lower part of the bridge of the brain (diagram).

1 - medial longitudinal bundle;

2 - upper vestibular nucleus; 3 - the core of the efferent nerve; 4 - spinal path of the trigeminal nerve; 5 - the nucleus of the spinal tract of the trigeminal nerve; 6 - the nucleus of the facial nerve; 7 - cortical-spinal and cortical-nuclear pathways; localization of the lesion in Raymond-Sestan syndromes (8) and cerebellopontine angle (9); VI, VII, VIII - cranial nerves

It involves damage to the facial and abducens nerves (in combination with gaze paralysis) on the side of the focus and hemiplegia, and sometimes hemianesthesia (due to damage to the medial loop) of the opposite limbs. Raymond-Sestan syndrome- a combination of gaze paresis towards the pathological focus, ataxia and choreoathetosis on the same side with hemiparesis and hemianesthesia on the opposite side.

Bulbar alternating syndromes(Fig. 5.34). Jackson Syndrome causes peripheral damage to the hypoglossal nerve on the side of the focus and hemiplegia or hemiparesis of the limbs of the opposite side. Avellis syndrome includes damage to the glossopharyngeal and vagus nerves (paralysis of the soft palate and vocal cord on the side of the focus with choking when eating, liquid food entering the nose, dysarthria and dysphonia) and hemiplegia on the opposite side. Syndrome

Rice. 5.34. The location of the nuclei of the cranial nerves on the transverse section of the medulla oblongata (scheme). 1 - thin core; 2 - posterior nucleus of the vagus nerve; 3 - lower vestibular nucleus; 4 - wedge-shaped nucleus; 5 - the core of a single path; 6 - the nucleus of the hypoglossal nerve; 7 - the nucleus of the spinal tract of the trigeminal nerve; 8 - dorsal-thalamic path; 9 - double core; 10 - pyramid; 11 - olive; 12 - medial loop; localization of the lesion in Jackson (13), Wallenberg-Zakharchenko (14), Tapia (15) syndromes; IX, X, XII - cranial nerves

Babinsky-Nageotte manifested by cerebellar symptoms in the form of hemiataxia, hemiasynergy, lateropulsion (as a result of damage to the lower cerebellar peduncle, olivocerebellar fibers), miosis or Bernard-Horner syndrome on the side of the focus and hemiplegia and hemianesthesia on the opposite side. Schmidt syndrome includes paralysis of the vocal cords, soft palate, trapezius and sternocleidomastoid muscles on the affected side (IX, X and XI nerves), hemiparesis of opposite limbs. For Wallenberg-Zakharchenko syndrome paralysis of the soft palate and vocal cords, anesthesia of the pharynx and larynx, sensitivity disorder on the face, hemiataxia (with damage to the cerebellar pathways) on the side of the focus and on the opposite side - hemiplegia, analgesia and thermal anesthesia are characteristic.

1. Olfactory nerve - has no nuclei, olfactory cells are located in the mucous membrane of the olfactory region of the nasal cavity. Contains visceral sensory fibers.

The exit from the brain is from the olfactory bulb.

The exit from the skull is from the ethmoid plate of the ethmoid bone.

The nerve is a collection of 15-20 thin nerve threads, which are the central processes of the olfactory cells. They pass through holes in the ethmoid bone and then end in the olfactory bulb, which continues into the olfactory tract and triangle.

2. Optic nerve - has no nuclei, ganglionic neurocytes are located in the retina of the eyeball. Contains somatic sensory fibers.

Exit from the brain - optic chiasm at the base of the brain

Exit from the skull - optic canal

Moving away from the posterior pole of the eyeball, the nerve leaves the orbit through the optic canal and, entering the cranial cavity together with the same nerve on the other side, forms the optic chiasm, which lies in the optic sulcus of the sphenoid bone. The continuation of the optic pathway beyond the chiasm is the optic tract, ending in the lateral geniculate body and in the superior colliculus of the roof of the midbrain.

3. Oculomotor nerve - has 2 nuclei: autonomic and motor, located in the tegmentum of the midbrain (at the level of the upper mounds). Contains efferent (motor) fibers to most of the external muscles of the eyeball and parasympathetic fibers to the internal eye muscles (ciliary muscles and muscles that narrow the pupil).

The exit from the brain is from the medial sulcus of the brain stem / interpeduncular fossa / from the oculomotor sulcus.

The oculomotor nerve leaves the brain along the medial edge of the brain stem, then goes to the superior orbital fissure, through which it enters the orbit.

Entering the orbit is divided into 2 branches:

A) Superior branch - to the superior rectus muscle of the eyeball and to the muscle that lifts the upper eyelid.

B) The lower branch - to the lower and medial rectus muscles of the eyeball and the lower oblique muscle of the eyeball. From the lower branch the nerve root departs to the ciliary node, carrying parasympathetic fibers for the ciliary muscle and the muscle that narrows the pupil.

4. Block nerve - has 1 motor nucleus, located in the tegmentum of the midbrain (at the level of the lower mounds). Contains only efferent (motor) fibers.

The exit from the brain is from under the lower hillocks / on the sides of the frenulum of the upper medullary velum.

The exit from the skull is the superior orbital fissure.

After leaving the brain, it goes around the brain stem laterally and through the superior orbital fissure enters the orbit, where it innervates the superior oblique muscle of the eyeball.

5. Trigeminal nerve - has 4 nuclei: 3 sensory and 1 motor nucleus. Located in the tegmentum of the midbrain, the tegmentum of the bridge, the tegmentum of the medulla oblongata. Contains afferent (sensory) fibers and efferent (motor) fibers.

The exit from the brain is the place of the bridge and the middle cerebellar peduncle.

The exit from the skull is the ophthalmic nerve - the superior orbital fissure, the maxillary nerve - a round hole, the mandibular nerve - an oval hole.

Branches of the trigeminal nerve:

1. The ophthalmic nerve enters the orbital cavity through the superior orbital fissure, but before entering it it is divided into 3 more branches:

a) The frontal nerve, runs directly anteriorly under the roof of the orbit through the supraorbital notch (or foramen) into the skin of the forehead, here it is called the supraorbital nerve, giving branches along the way into the skin of the upper eyelid and medial angle of the eye.

b) Lacrimal nerve, go to the lacrimal gland and, passing through it, ends in the skin and conjunctiva of the lateral corner of the eye. Before entering the lacrimal gland, it connects to the zygomatic nerve (from the second branch of the trigeminal nerve). Through this anastomosis, the lacrimal nerve receives secretory fibers for the lacrimal gland and supplies it with sensory fibers as well.

c) Nasociliary nerve, innervates the anterior part of the nasal cavity (anterior and posterior ethmoid nerves), the eyeball (long ciliary nerves), the skin of the medial angle of the eye, the conjunctiva and the lacrimal sac (subtrochlear nerve).

2. The maxillary nerve exits the cranial cavity through a round opening into the pterygopalatine fossa; from here, its direct continuation is the infraorbital nerve, which goes through the inferior orbital fissure to the infraorbital groove and canal on the lower wall of the orbit and then exits through the supraorbital foramen to the face, where it splits into a bundle of branches. These branches, connecting with the branches of the facial nerve, innervate the skin of the lower eyelid, lateral surface of the nose and lower lip..

Branches of the maxillary and its continuation of the infraorbital nerves:

a) Zygomatic nerve, Inn. skin of the cheek and anterior part of the temporal region.

b) The upper alveolar nerves, in the thickness of the upper jaw, form a plexus, from which the upper alveolar branches and branches innervating the upper gums depart.

c) Nodal nerves connect the maxillary nerve with the pterygopalatine ganglion, which belongs to the autonomic nervous system.

3. The mandibular nerve, has in its composition, in addition to the sensory, the entire motor root of the trigeminal nerve. Upon exiting the skull through the foramen ovale, it divides into 2 groups of branches:

a) Muscular branches: to all the masticatory muscles, to the muscle that strains the palatine curtain, to the muscle that strains the eardrum, to the maxillohyoid muscle and the anterior belly of the digastric muscle, the corresponding nerves go.

b) Sensitive branches:

- The buccal nerve goes to the buccal mucosa.

The lingual nerve is located under the mucous membrane of the floor of the mouth.

Having given the hypoglossal nerve to the mucous membrane of the floor of the mouth, it innervates the mucous membrane of the back of the tongue for the anterior two-thirds. It is joined by a thin branch emerging from the stony-tympanic fissure, carrying parasympathetic fibers from the superior salivary nucleus (related to the facial nerve) - a tympanic string, which will provide innervation for the hyoid and sublingual salivary glands. The drum string also carries taste fibers from the anterior two-thirds of the tongue.

3. The lower alveolar nerve, through the mandibular foramen, together with the artery of the same name, goes into the canal of the lower jaw, where it gives branches to all the lower teeth, having previously formed a plexus. At the anterior end of the mandibular canal, the nerve gives off a thick branch - the mental nerve, which emerges from the mental foramen and extends into the skin of the chin and lower lip.

4. Auriculotemporal nerve, penetrates into the upper part of the parotid gland and goes to the temporal region, accompanying the superficial temporal artery. Gives secretory branches to the parotid gland, as well as sensitive fibers to the temporomandibular joint, to the skin of the anterior part of the auricle, external auditory canal and to the skin of the temple.

6. Abducens nerve - has one motor nucleus located in the pons tire. Contains only

The exit from the brain is from the groove between the bridge and the pyramid.

The exit from the skull is the superior orbital fissure.

It leaves the brain between the bridge and the pyramid, passes through the superior orbital fissure into the orbit and enters the lateral rectus muscle of the eyeball.

7. Facial nerve - incorporates motor, autonomic and sensory nuclei, located in the cover of the bridge. It contains efferent (motor), afferent (sensory) and parasympathetic fibers.

The exit from the brain is behind the middle cerebellar peduncle / cerebellopontine angle.

Exit from the skull - internal auditory canal - facial canal - stylomastoid opening.

The facial nerve enters the surface of the brain laterally along the posterior edge of the pons, next to the vestibulocochlear nerve. Then, together with the last nerve, it enters the internal auditory meatus and enters the facial canal. In the canal, the nerve first goes horizontally, heading outward, then in the area of ​​​​the gap of the canal of the large stony nerve, it turns back at a right angle and also runs horizontally along the inner wall of the tympanic cavity in its upper part. Having passed the limits of the tympanic cavity, the nerve again bends and descends vertically down, leaving the skull through the stylomastoid foramen. When exiting, the nerve enters the thickness of the parotid gland and is divided into terminal branches.

Gives the following branches before exiting the channel :

- The large stony nerve originates in the area of ​​the knee and exits through the gap of the canal of the large stony nerve; then it goes along the groove of the same name on the anterior surface of the temporal bone pyramid, passes into the pterygoid canal along with the sympathetic nerve, the deep stony nerve, forming with it the nerve of the pterygopalatine canal and reaches the pterygopalatine node.

The nerve is interrupted at the node and its fibers as part of the posterior nasal and palatine nerves go to the glands of the mucous membrane of the nose and palate; part of the fibers in the zygomatic nerve through connections with the lacrimal nerve reaches the lacrimal gland. The posterior nasal branches also give off the nasopalatine nerve to the glands of the mucous membrane of the hard palate. The palatine nerves innervate the glands of the mucous membrane of the soft and hard palate.

- stapedial nerve, innervates the corresponding muscle.

- drum string, having separated from the facial nerve in the lower part of the facial canal, penetrates into the tympanic cavity, lies there on the medial surface of the tympanic membrane, and then leaves through the stony-tympanic fissure; leaving the gap to the outside, it joins the lingual nerve, supplying the anterior two-thirds of the tongue with taste fibers. The secretory part approaches the submandibular node and, after a break in it, supplies the submandibular and sublingual salivary glands with secretory fibers.

After exiting the stylomastoid foramen, it gives the following branches:

- Posterior ear nerve, innervates the posterior ear muscle and the occipital abdomen of the cranial vault.

- Digastric branch, innervates the posterior belly of the digastric muscle and the stylohyoid muscle.

- parotid plexus, formed by numerous branches to the facial muscles of the face:

Temporal branches - Inn. upper and anterior ear muscles, frontal belly of the cranial vault, circular muscle of the eye;

Zygomatic branches - inn. circular muscle of the eye and zygomatic muscle;

Buccal branches - to the muscles of the circumference of the mouth and nose;

Marginal mandibular branch - a branch that runs along the edge of the lower jaw to the muscles of the chin and lower lip;

Neck branch - inn. superficial neck muscle.

Intermediate nerve, is a mixed nerve. It contains afferent (gustatory) fibers going to its sensory nucleus (single nucleus) and efferent (secretory, parasympathetic) fibers coming from its autonomic (secretory) nucleus (superior salivary nucleus). The intermediate nerve exits the brain as a thin trunk between the facial and vestibulocochlear nerves, after passing some distance, joins the facial nerve, becomes its integral part. Further, it passes into a large stony nerve. Conducts sensory impulses from the taste buds of the anterior part of the tongue and soft palate. Secretory parasympathetic fibers are sent to the submandibular and sublingual salivary glands.

8. Vestibulocochlear nerve, has in its composition 6 sensitive nuclei located in the cover of the bridge. It contains only afferent (sensory) fibers.

The exit from the brain is lateral to the facial nerve, from the cerebellopontine angle.

The exit from the skull is the internal auditory meatus.

It consists of two parts: the vestibular part and the cochlear part. Sensory fibers are responsible for the specific innervation of the organ of hearing (fibers from the cochlear nuclei; cochlear part) and the specific innervation of the balance organ (fibers from the vestibular nuclei; vestibular part).

9. The glossopharyngeal nerve has 3 different nuclei: motor, autonomic and sensory, located in the tegmentum of the medulla oblongata. It contains efferent (motor) fibers, parasympathetic fibers and afferent (motor) fibers.

Out of the brain - lateral to the two previous nerves / from the posterolateral groove, behind the olive.

The glossopharyngeal nerve emerges with its roots from the medulla oblongata behind the olive, above the vagus nerve, and together with the latter leaves the skull through the jugular foramen. Within the jugular foramen, the sensitive part of the nerve forms the upper node, and upon exiting the hole, the lower node, which lies on the lower surface of the temporal bone pyramid. The nerve descends, first between the internal jugular vein and the internal carotid artery, and then goes around the stylohyoid muscle from behind and, along the lateral side of this muscle, approaches the root of the tongue in a gentle arc, where it divides into terminal branches.

Branches of the glossopharyngeal nerve:

The tympanic nerve departs from the lower node and enters the tympanic cavity, where it forms the tympanic plexus, to which branches also come from the sympathetic plexus with the internal carotid artery. This plexus innervates the mucous membrane of the tympanic cavity and the auditory tube. After exiting the tympanic cavity through the upper wall, it will be called the small stony nerve, which passes to the groove of the same name, along the anterior surface of the temporal bone pyramid and reaches the ear node.

Parasympathetic secretory fibers for the parotid gland are brought to this node; after switching fibers at this node, the postganglionic fibers go as part of the auriculotemporal nerve (the third branch of the trigeminal nerve).

The stylo-pharyngeal branch innervates the muscle of the same name.

Tonsil branches innervate the mucous membrane of the palatine tonsils and arches.

Pharyngeal branches go to the pharyngeal plexus.

The lingual branches, the terminal branches of the glossopharyngeal nerve, are sent to the mucous membrane of the posterior third of the tongue, supplying sensory fibers, among which the taste fibers also pass.

Branch of the carotid sinus, sensory nerve to the carotid sinus.

10. The vagus nerve has 3 different nuclei: motor, autonomic and sensory nuclei, located in the tegmentum of the medulla oblongata. It contains efferent (motor), afferent (sensory) and parasympathetic fibers.

The exit from the brain is from the posterolateral groove, behind the olive.

The exit from the skull is the jugular foramen.

Fibers of all kinds exit the medulla oblongata in its posterior lateral groove, below the glossopharyngeal nerve, in 10-15 roots, which form a thick nerve trunk that leaves the cranial cavity through the jugular foramen. In the jugular foramen, the sensitive part of the nerve forms top node, and after leaving the hole bottom node. Upon exiting the cranial cavity, the vagus nerve trunk descends to the neck behind the vessels in the groove, first between the internal jugular vein and the internal carotid artery, and then between the same vein and the common carotid artery.

The vagus nerve then passes through the superior thoracic inlet into the thoracic cavity, where its right trunk is located in front of the subclavian artery, and the left one is on the front side of the aortic arch. Going down, both vagus nerves bypass the root of the lung behind on both sides and accompany the esophagus, forming plexuses on its walls, moreover, the left nerve - passes along the front side, and the right - along the right side. Together with the esophagus, both vagus nerves penetrate through the esophageal opening into the abdominal cavity, where they form plexuses on the walls of the stomach.

Branches of the vagus nerves:

A) At the head:

Meningeal branch - Inn. hard shell of the brain in the region of the posterior cranial fossa.

Ear branch - Inn. the back wall of the external auditory canal and part of the skin of the auricle.

B) In the neck:

The pharyngeal nerves, together with the branches of the glossopharyngeal nerve, form the pharyngeal plexus; pharyngeal branches of the vagus nerve innervate constrictors of the pharynx, muscles of the palatine arches and soft palate; the pharyngeal plexus also provides sensory innervation to the pharyngeal mucosa.

The superior laryngeal nerve supplies sensory fibers to the mucous membrane of the larynx above the glottis, part of the root of the tongue and epiglottis, and motor fibers - part of the muscles of the larynx and the lower constrictor of the pharynx.

3. Superior and inferior cardiac cervical branches, form the heart plexus.

B) In the chest:

The recurrent laryngeal nerve, on the right side, this nerve bends around the subclavian artery from below and behind, and on the left side, also from below and behind the aortic arch and then rises upward in the groove between the esophagus and trachea, giving numerous esophageal and tracheal branches. The end of the nerve, called the lower laryngeal nerve, innervates part of the muscles of the larynx, its mucous membrane below the vocal folds, the mucous membrane of the root of the tongue near the epiglottis, as well as the trachea, pharynx and esophagus, thyroid and thymus glands, lymph nodes of the neck, heart and mediastinum.

Cardiac thoracic branches go to the cardiac plexus.

Bronchial and tracheal branches, parasympathetic, together with the branches of the sympathetic trunk form the pulmonary plexus on the walls of the bronchi. Due to the branches of this plexus, the muscles and glands of the trachea and bronchi are innervated, and in addition, it contains sensory fibers for the trachea, bronchi and lungs.

Esophageal branches go to the wall of the esophagus.

D) in the abdomen:

The plexus of the vagus nerves, going through the esophagus, continues to the stomach, forming pronounced trunks (anterior and posterior). The continuation of the left vagus nerve, descending from the anterior side of the esophagus to the anterior wall of the stomach, forms anterior gastric plexus, located mainly along the lesser curvature of the stomach, from which depart mixed with sympathetic branches anterior gastric branches.

The continuation of the right vagus nerve, descending along the posterior wall of the esophagus, is the posterior gastric plexus, in the region of the lesser curvature of the stomach, which gives off the posterior gastric branches. In addition, most of the fibers of the right vagus nerve in the form of celiac branches go along with the left gastric artery to the celiac trunk, and from here along the branches of the vessels, along with the sympathetic plexuses, to the liver, spleen, pancreas, kidneys, small and large intestine to the sigmoid.

11. Accessory nerve, has 1 motor nucleus, located in the tegmentum of the medulla oblongata. It contains only efferent (motor) fibers.

The exit from the brain is from the same furrow as the vagus nerve, below it.

The exit from the skull is the jugular foramen.

According to the nuclei in the nerve, the cerebral and spinal parts are distinguished. cerebral part emerges from the medulla oblongata below the vagus nerve . spinal part accessory nerve is formed between the anterior and posterior roots of the spinal nerves (from 2-5) and partly from the anterior roots of the three upper cervical nerves, rises in the form of a nerve stem and joins the cerebral part. The accessory nerve, together with the vagus nerve, exits the cranial cavity through the jugular foramen and innervates the trapezius muscle of the back and the sternocleidomastoid muscle. The cerebral portion of the accessory nerve, together with the recurrent laryngeal nerve, innervates the muscles of the larynx.

12. The hypoglossal nerve has one motor nucleus located in the tegmentum of the medulla oblongata. Contains only efferent (motor) fibers.

The exit from the brain is the anterolateral sulcus of the medulla oblongata, between the pyramid and the olive.

The exit from the skull is the hyoid canal.

Appearing at the base of the brain between the pyramid and the olive with several roots, the nerve then passes in the canal of the same name of the occipital bone, descends down the lateral side of the internal carotid artery, passes under the posterior belly of the digastric muscle and goes in the form of an arc, convex downwards, along the lateral surface of the hyoid-lingual muscle. One of the branches of the nerve, the upper root, goes down, connects with the lower root of the cervical plexus and forms a cervical loop with it. From this loop, the muscles located below the hyoid bone are innervated. + Innervates the derivatives of the occipital myotomes - all the muscles of the tongue.

The brain (encephalon) is divided into brain stem, big brain and cerebellum. In the brain stem there are structures related to the segmental apparatus of the brain, and subcortical integration centers. From the brain stem, as well as from the spinal cord, nerves depart. They got the name cranial nerves.

There are 12 pairs of cranial nerves. They are designated by Roman numerals in the order of their location from bottom to top. Unlike spinal nerves, which are always mixed (both sensory and motor), cranial nerves can be sensory, motor, and mixed. Sensory cranial nerves: I - olfactory, II - visual, VIII - auditory. There are also five purely motor: III - oculomotor, IV - block, VI - efferent, XI - additional, XII - sublingual. And four mixed: V - trigeminal, VII - facial, IX - glossopharyngeal, X - wandering. In addition, some cranial nerves contain autonomic nuclei and fibers.

Characterization and description of individual cranial nerves:

I couple - olfactory nerves(nn.olfactorii). Sensitive. It is formed by 15-20 olfactory filaments, consisting of axons of olfactory cells located in the mucous membrane of the nasal cavity. The threads enter the skull and end in the olfactory bulb, from where the olfactory path begins to the cortical end of the olfactory analyzer - the hippocampus.

When the olfactory nerve is damaged, the sense of smell is disturbed.

II pair - optic nerve(n. opticus). Sensitive. Consists of nerve fibers formed by processes of nerve cells in the retina. The nerve enters the cranial cavity, forms the optic chiasm in the diencephalon, from which the visual tracts begin. The function of the optic nerve is the transmission of light stimuli.

With the defeat of various parts of the visual analyzer, there are disorders associated with a decrease in visual acuity up to complete blindness, as well as disturbances in light perception and visual fields.

III pair - oculomotor nerve(n. oculomotorius). Mixed: motor, vegetative. It starts from the motor and autonomic nuclei located in the midbrain.

The oculomotor nerve (motor part) innervates the muscles of the eyeball and upper eyelid.

Parasympathetic fibers the oculomotor nerve is innervated by smooth muscles that constrict the pupil; they also approach the muscle that changes the curvature of the lens, as a result of which the accommodation of the eye changes.

If the oculomotor nerves are damaged, strabismus occurs, accommodation is disturbed, and the size of the pupil changes.

IV pair - trochlear nerve(n. trochlearis). Motor. It starts from the motor nucleus located in the midbrain. Innervates the superior oblique muscle of the eye.

V pair - trigeminal nerve(n. trigeminus). Mixed: motor and sensory.

It has three sensitive cores where the fibers coming from the trigeminal ganglion end:

- bridge in the hindbrain,

- the lower nucleus of the trigeminal nerve in the medulla oblongata,

- mesencephalon in the midbrain.

Sensory neurons receive information from the receptors of the skin of the face, from the skin of the lower eyelid, nose, upper lip, teeth, upper and lower gums, from the mucous membranes of the nasal and oral cavities, tongue, eyeball and from the meninges.

Motor nucleus located in the cover of the bridge. Motor neurons innervate the muscles of mastication, muscles of the palatine curtain, as well as muscles that contribute to the tension of the tympanic membrane.

When a nerve is damaged, paralysis of the masticatory muscles occurs, a violation of sensitivity in the corresponding areas up to its loss, and pain occurs.

VI pair - abducens nerve(n. abducens). Motor. The core is located in the bridge tire. Innervates only one muscle of the eyeball - the external straight line, which moves the eyeball outward. When it is damaged, convergent strabismus is observed.

VII pair - facial nerve(n. facialis). Mixed: motor, sensory, vegetative.

Motor nucleus located in the cover of the bridge. It innervates the mimic muscles, the circular muscle of the eye, mouth, the muscle of the auricle and the subcutaneous muscle of the neck.

sensitive — single path core medulla oblongata. This receives information on sensitive taste fibers, starting from the taste buds located in the anterior 2/3 of the tongue.

Vegetative — superior salivary nucleus located in the cover of the bridge. Efferent parasympathetic salivary fibers begin from it to the sublingual and submandibular, as well as the parotid salivary and lacrimal glands.

If the facial nerve is damaged, the following disorders are observed: paralysis of the facial muscles occurs, the face becomes asymmetrical, speech becomes difficult, swallowing is disturbed, taste and tearing are disturbed, etc.

VIII pair - vestibulocochlear nerve(n. vestibulocochlearis). Sensitive. Allocate snails and vestibular nuclei located in the lateral divisions of the rhomboid fossa in the medulla oblongata and the pontine tegmentum. Sensory nerves (auditory and vestibular) are formed by sensory nerve fibers coming from the organs of hearing and balance.

When the vestibular nerve is damaged, dizziness, rhythmic twitching of the eyeballs, and staggering when walking often occur. Damage to the auditory nerve leads to hearing loss, the appearance of sensations of noise, squeak, rattle.

IX pair - glossopharyngeal nerve(n. glosspharyngeus). Mixed: motor, sensory, vegetative.

sensitive core — single path core medulla oblongata. This nucleus is common with the nucleus of the facial nerve. From the glossopharyngeal nerve depends on the perception of taste in the back third of the tongue. Thanks to the glossopharyngeal nerve, the sensitivity of the mucous membranes of the pharynx, larynx, trachea, and soft palate is also provided.

Motor nucleus— double core, located in the medulla oblongata, innervates the muscles of the soft palate, epiglottis, pharynx, larynx.

Vegetative nucleus- parasympathetic inferior salivary nucleus medulla oblongata, which innervates the parotid, submandibular and sublingual salivary glands.

When this cranial nerve is damaged, there is a violation of taste in the posterior third of the tongue, dry mouth is observed, a violation of the sensitivity of the pharynx occurs, paralysis of the soft palate is observed, choking when swallowing.

X pair — nervus vagus(n. vagus). Mixed nerve: motor, sensory, autonomic.

sensitive core — single path core medulla oblongata. Sensitive fibers transmit irritation from the dura mater, from the mucous membranes of the pharynx, larynx, trachea, bronchi, lungs, gastrointestinal tract and other internal organs. Most of the interoreceptive sensations are associated with the vagus nerve.

Motor — double core medulla oblongata, fibers from it go to the striated muscles of the pharynx, soft palate, larynx and epiglottis.

Autonomic nucleus - dorsal nucleus of the vagus nerve(medulla oblongata) forms the longest processes of neurons in comparison with other cranial nerves. Innervates the smooth muscles of the trachea, bronchi, esophagus, stomach, small intestine, upper part of the large intestine. This nerve also innervates the heart and blood vessels.

When the vagus nerve is damaged, the following symptoms occur: the taste is disturbed in the posterior third of the tongue, the sensitivity of the pharynx and larynx is lost, paralysis of the soft palate occurs, sagging of the vocal cords, etc. Some similarity in the symptoms of damage to the IX and X pairs of cranial nerves is due to the presence of nuclei in the brain stem that they have in common.

XI pair - accessory nerve(n. accessorius). motor nerve. It has two nuclei: in the medulla oblongata and in the spinal cord. Innervates the sternocleidomastoid muscle and the trapezius muscle. The function of these muscles is to turn the head in the opposite direction, raise the shoulder blades, raise the shoulders above the horizontal.

In case of damage, there is difficulty in turning the head to the healthy side, a lowered shoulder, limited raising of the arm above the horizontal line.

XII pair - hypoglossal nerve(n. hypoglossus). This is the motor nerve. The nucleus is located in the medulla oblongata. The fibers of the hypoglossal nerve innervate the muscles of the tongue and partly the muscles of the neck.

When damaged, either weakness of the muscles of the tongue (paresis) or their complete paralysis occurs. This leads to a violation of speech, it becomes indistinct, weaving.

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cranial nerves

The cranial nerves are 12 pairs. Each pair has its own name and serial number, denoted by a Roman numeral: olfactory nerves - I pair; optic nerve - II pair; oculomotor nerve - III pair; trochlear nerve - IV pair; trigeminal nerve - V pair; abducens nerve - VI pair; facial nerve - VII pair; vestibulocochlear nerve - VIII pair; glossopharyngeal nerve - IX pair; vagus nerve - X pair; accessory nerve - XI pair; hypoglossal nerve - XII pair.

The cranial nerves differ in function and therefore in the composition of the nerve fibers. Some of them (I, II and VIII pairs) are sensitive, others (III, IV, VI, XI and XII pairs) are motor, and the third (V, VII, IX and X pairs) are mixed. The olfactory and optic nerves differ from other nerves in that they are derivatives of the brain - they were formed by protrusion from the brain bubbles and, unlike other sensory and mixed nerves, do not have nodes. These nerves consist of processes of neurons located on the periphery - in the organ of smell and the organ of vision. Mixed in function, cranial nerves are similar in structure and composition of nerve fibers to spinal nerves. Their sensitive part has nodes (sensitive nodes of the cranial nerves), similar to the spinal nodes. The peripheral processes (dendrites) of the neurons of these nodes go to the periphery to the organs and end in receptors in them, and the central processes follow to the brain stem to sensitive nuclei, similar to the nuclei of the dorsal horns of the spinal cord. The motor part of the mixed cranial nerves (and motor cranial nerves) consist of axons of nerve cells of the motor nuclei of the brain stem, similar to the nuclei of the anterior horns of the spinal cord. As part of III, VII, IX and X pairs of nerves, along with other nerve fibers, parasympathetic fibers pass (they are axons of neurons of the autonomic nuclei of the brain stem, similar to the autonomic parasympathetic nuclei of the spinal cord).

The olfactory nerve is sensitive in function, consists of nerve fibers that are processes of the olfactory cells of the olfactory organ. These fibers form 15-20 olfactory filaments (nerves) that leave the olfactory organ and through the ethmoid plate of the ethmoid bone penetrate into the cranial cavity, where they approach the neurons of the olfactory bulb, nerve impulses are transmitted through various formations of the peripheral part of the olfactory brain to its central part.

The optic nerve is sensitive in function, consists of nerve fibers that are processes of the so-called ganglion cells of the retina of the eyeball. From the orbit through the optic canal, the nerve passes into the cranial cavity, where it immediately forms a partial intersection with the nerve of the opposite side (optic chiasm) and continues into the optic tract. Due to the fact that only the medial half of the nerve passes to the opposite side, the right optic tract contains nerve fibers from the right halves, and the left tract from the left halves of the retina of both eyeballs. The optic tracts approach the subcortical visual centers - the nuclei of the superior hillocks of the roof of the midbrain, the lateral geniculate bodies, and the thalamic cushions. The nuclei of the superior hillocks are connected with the nuclei of the oculomotor nerve (the pupillary reflex is carried out through them) and with the nuclei of the anterior horns of the spinal cord (orienting reflexes to sudden light stimuli are carried out). From the nuclei of the lateral geniculate bodies and the pillows of the thalamus, nerve fibers in the composition of the white matter of the hemispheres follow to the cortex of the occipital lobes (visual sensory cortex).

oculomotor nerve in function motor, consists of motor somatic and efferent parasympathetic nerve fibers. These fibers are the axons of the neurons that make up the nuclei of the nerve. There are motor nuclei and an additional parasympathetic nucleus. They are located in the brain stem at the level of the superior hillocks of the roof of the midbrain. The nerve exits the cranial cavity through the superior orbital fissure into the orbit and divides into two branches: superior and inferior. The motor somatic fibers of these branches innervate the superior, medial, inferior rectus and inferior oblique muscles of the eyeball, as well as the muscle that lifts the upper eyelid (they are all striated), and the parasympathetic fibers innervate the muscle that narrows the pupil and the ciliary muscle (both smooth) . Parasympathetic fibers on the way to the muscles switch in the ciliary node, which lies in the posterior part of the orbit.

Block nerve in function motor, consists of nerve fibers extending from the nucleus. The nucleus is located in the cerebral peduncles at the level of the inferior colliculus of the roof of the midbrain. The nerve exits the cranial cavity through the superior orbital fissure into the orbit and innervates the superior oblique muscle of the eyeball.

The trigeminal nerve is mixed in function, consists of sensory and motor nerve fibers. Sensitive nerve fibers are peripheral processes (dendrites) of neurons of the trigeminal ganglion, which is located on the anterior surface of the pyramid of the temporal bone at its apex, between the sheets of the dura mater of the brain, and consists of sensitive nerve cells. These nerve fibers form three branches of the nerve: the first branch is the ophthalmic nerve, the second branch is the maxillary nerve, and the third branch is the mandibular nerve. The central processes (axons) of the neurons of the trigeminal ganglion make up the sensory root of the trigeminal nerve, which goes to the brain to the sensory nuclei. The trigeminal nerve has several sensory nuclei (located in the pons, cerebral peduncles, medulla oblongata, and upper cervical segments of the spinal cord). From the sensory nuclei of the trigeminal nerve, nerve fibers go to the thalamus. The corresponding neurons of the thalamic nuclei are connected by means of fibers extending from them with the lower section of the postcentral gyrus (its cortex).

The motor fibers of the trigeminal nerve are processes of the neurons of its motor nucleus located in the bridge. These fibers exit the brain to form the motor root of the trigeminal nerve, which joins its third branch, the mandibular nerve.

The ophthalmic nerve, or the first branch of the trigeminal nerve, is sensitive in function. Departing from the trigeminal node, it goes to the superior orbital fissure and through it penetrates into the orbit, where it is divided into several branches. They innervate the skin of the forehead and upper eyelid, the conjunctiva of the upper eyelid and the shell of the eyeball (including the cornea), the mucous membrane of the frontal and sphenoid sinuses and parts of the cells of the ethmoid bone, as well as part of the hard shell of the brain. The largest branch of the optic nerve is called the frontal nerve.

The maxillary nerve, or the second branch of the trigeminal nerve, is sensitive in function, follows from the cranial cavity through a round opening into the pterygopalatine fossa, where it divides into several branches. The largest branch is called the infraorbital nerve, passes through the canal of the same name in the upper jaw and enters the face in the region of the canine fossa through the infraorbital foramen. The region of innervation of the branches of the maxillary nerve: the skin of the middle part of the face (upper lip, lower eyelid, zygomatic region, nasal cavity, palate, maxillary sinus, parts of the cells of the ethmoid bone, upper teeth and part of the hard shell of the brain).

The mandibular nerve, or the third branch of the trigeminal nerve, is mixed in function. From the cranial cavity through the foramen ovale, it passes into the infratemporal fossa, where it divides into a number of branches. Sensitive branches innervate the skin of the lower lip, chin and temporal region, the mucous membrane of the lower lip, and the hard shell of the brain. The motor branches of the mandibular nerve innervate all the masticatory muscles, the muscle that strains the palatine curtain, the maxillohyoid muscle and the anterior belly of the digastric muscle. The largest branches of the mandibular nerve: the lingual nerve (sensory, goes to the tongue) and the inferior alveolar nerve (sensory, passes through the mandibular canal, gives branches to the lower teeth, under the name of the mental nerve through the opening of the same name goes to the chin).

Abducens nerve in function, the motor consists of nerve fibers extending from the neurons of the nerve nucleus located in the bridge. It exits the skull through the superior orbital fissure into the orbit and innervates the lateral (external) rectus muscle of the eyeball.

The facial nerve, or intermediate facial nerve, is mixed in function and includes motor somatic fibers, secretory parasympathetic fibers, and sensory taste fibers. Motor fibers depart from the nucleus of the facial nerve, located in the bridge. Secretory parasympathetic and sensory taste fibers are part of the intermediate nerve, which has parasympathetic and sensory nuclei in the pons and exits the brain near the facial nerve. Both nerves (both facial and intermediate) follow the internal auditory canal, in which the intermediate nerve enters the facial. After that, the facial nerve penetrates into the canal of the same name, located in the pyramid of the temporal bone. In the canal, it gives off several branches: a large stony nerve, a drum string, etc. A large stony nerve contains secretory parasympathetic fibers to the lacrimal gland. The drum string passes through the tympanic cavity and, after leaving it, joins the lingual nerve from the third branch of the trigeminal nerve; it contains taste fibers for the taste buds of the body and the tip of the tongue, and secretory parasympathetic fibers in the submandibular and sublingual salivary glands.

Having given up its branches in the canal, the facial nerve leaves it through the stylomastoid foramen, enters the thickness of the parotid salivary gland, where it divides into terminal branches that are motor in function. They innervate all the mimic muscles of the face and part of the muscles of the neck: the subcutaneous muscle of the neck, the posterior belly of the digastric muscle, etc.

The vestibulocochlear nerve is sensitive in function, includes two parts: the cochlear - for the sound-perceiving organ (spiral organ) and the vestibular - for the vestibular apparatus (balance organ). Each part has a ganglion of sensory neurons located in the pyramid of the temporal bone near the inner ear.

The cochlear part (cochlear nerve) consists of the central processes of the cells of the cochlear ganglion (cochlear ganglion).

The peripheral processes of these cells approach the receptor cells of the spiral organ in the cochlea of ​​the inner ear.

The vestibular part (vestibule nerve) is a bundle of central processes of the cells of the vestibular ganglion. The peripheral processes of these cells end on the receptor cells of the vestibular apparatus in the sac, uterus and ampullae of the semicircular ducts of the inner ear.

Both parts - both the cochlear and the vestibular - from the inner ear follow side by side along the internal auditory canal to the bridge (of the brain), where the nuclei are located. The nuclei of the cochlear part of the nerve are connected with the subcortical auditory centers - the nuclei of the lower hillocks of the roof of the midbrain and the medial geniculate bodies. From the neurons of these nuclei, nerve fibers go to the middle part of the superior temporal gyrus (auditory cortex). The nuclei of the lower colliculi are also connected with the nuclei of the anterior horns of the spinal cord (orienting reflexes to sudden sound stimuli are carried out). The nuclei of the vestibular part of the VIII pair of cranial nerves are associated with the cerebellum.

The glossopharyngeal nerve is mixed in function, including sensory general and gustatory fibers, motor somatic fibers and secretory parasympathetic fibers. Sensitive fibers innervate the mucous membrane of the root of the tongue, pharynx and tympanic cavity, taste fibers - the taste buds of the root of the tongue. The motor fibers of this nerve innervate the stylo-pharyngeal muscle, and the secretory parasympathetic fibers innervate the parotid salivary gland.

The nuclei of the glossopharyngeal nerve (sensory, motor, and parasympathetic) are located in the medulla oblongata, some of which are shared with the vagus nerve. The nerve leaves the skull through the jugular foramen, goes down and anteriorly towards the root of the tongue divides into its branches to the corresponding organs (tongue, pharynx, tympanic cavity).

The vagus nerve is mixed in function, consists of sensory, motor somatic and efferent parasympathetic nerve fibers. Sensitive fibers branch in various internal organs, where they have sensitive nerve endings - visceroreceptors. One of the sensory branches, the depressor nerve, terminates in receptors in the aortic arch and plays an important role in the regulation of blood pressure. Relatively thin sensitive branches of the vagus nerve innervate part of the hard shell of the brain and a small area of ​​skin in the external auditory canal. The sensitive part of the nerve has two nodes (upper and lower) lying in the jugular foramen of the skull.

Motor somatic fibers innervate the muscles of the pharynx, the muscles of the soft palate (with the exception of the muscle that strains the palatine curtain) and the muscles of the larynx. Parasympathetic fibers of the vagus nerve innervate the heart muscle, smooth muscles and glands of all internal organs of the chest cavity and abdominal cavity, with the exception of the sigmoid colon and the pelvic organs. Parasympathetic efferent fibers can be subdivided into parasympathetic motor and parasympathetic secretory fibers.

The vagus nerve is the largest of the cranial nerves and gives off numerous branches. The nerve nuclei (sensory, motor and autonomic - parasympathetic) are located in the medulla oblongata.

Neurology of motor cranial nerves

The nerve exits the cranial cavity through the jugular foramen, on the neck lies next to the internal jugular vein and with the internal, and then with the common carotid artery; in the chest cavity it approaches the esophagus (the left nerve passes along its anterior, and the right nerve passes along its posterior surface) and, together with it, penetrates the abdominal cavity through the diaphragm. In accordance with the location in the vagus nerve, the head, cervical, thoracic and abdominal regions are distinguished.

Branches extend from the head to the dura mater and to the area of ​​the skin of the external auditory canal.

The pharyngeal branches depart from the cervical region (to the pharynx and muscles of the soft palate), the superior laryngeal and recurrent nerve (innervate the muscles and mucous membrane of the larynx), the upper cervical cardiac branches, etc.

The thoracic cardiac branches, bronchial branches (to the bronchi and lungs) and branches to the esophagus depart from the thoracic region.

Branches depart from the abdominal region, participating in the formation of nerve plexuses that innervate the stomach, small intestine, large intestine from the beginning to the sigmoid colon, liver, pancreas, spleen, kidneys and testicles (in women - the ovaries). These plexuses are located around the arteries of the abdominal cavity.

The vagus nerve is the main parasympathetic nerve in terms of fiber composition and area of ​​innervation.

accessory nerve in function motor, consists of nerve fibers extending from the neurons of the motor nuclei. These nuclei are located in the medulla oblongata and in the I cervical segment of the spinal cord. The nerve exits the skull through the jugular foramen to the neck and innervates the sternomastoideus and trapezius muscles.

hypoglossal nerve in function motor, includes nerve fibers extending from the neurons of the motor nucleus located in the medulla oblongata. It leaves the cranial cavity through the canal of the hyoid nerve in the occipital bone, follows, describing an arc, to the tongue from below and is divided into branches that innervate all the muscles of the tongue and the geniohyoid muscle. One of the branches of the hypoglossal nerve (descending) forms, together with the branches of the I-III cervical nerves, the so-called cervical loop. The branches of this loop (due to fibers from the cervical spinal nerves) innervate the muscles of the neck, which lie below the hyoid bone.

All cranial nerves are presented in the table (Appendix No. 1). Their type, the organ innervated by them and its functions are also considered there.

So, motor nerves originate in the motor nuclei of the brainstem. A group of nerves is predominantly motor: oculomotor (3rd), trochlear (4th), abducens (6th), accessory (11th), hyoid (12th).

Oculomotor nerve (3rd)

The oculomotor nerve innervates the medial rectus, inferior rectus, superior rectus, inferior oblique, levator levator lid, and pupillary sphincter.

Innervates the external muscles of the eye (with the exception of the external rectus and superior oblique), the muscle that lifts the upper eyelid, the muscle that narrows the pupil, the ciliary muscle, which regulates the configuration of the lens, which allows the eye to adapt to near and far vision.

System III pair consists of two neurons. The central one is represented by the cells of the cortex of the precentral gyrus, the axons of which, as part of the cortical-nuclear pathway, approach the nuclei of the oculomotor nerve of both their own and the opposite side.

A wide variety of functions performed by the III pair is carried out with the help of 5 nuclei for the innervation of the right and left eyes. They are located in the brain peduncles at the level of the superior colliculus of the roof of the midbrain and are peripheral neurons of the oculomotor nerve. From two large cell nuclei, the fibers go to the external muscles of the eye on their own and partially opposite side. The fibers that innervate the muscle that lifts the upper eyelid come from the nucleus of the same and opposite sides. From two small cell accessory nuclei, parasympathetic fibers are sent to the muscle, the constrictor pupil, of their own and the opposite side. This ensures a friendly reaction of the pupils to light, as well as a reaction to convergence: constriction of the pupil with simultaneous contraction of the direct internal muscles of both eyes. From the posterior central unpaired nucleus, which is also parasympathetic, the fibers are sent to the ciliary muscle, which regulates the degree of bulge of the lens. When looking at objects located near the eye, the bulge of the lens increases and at the same time the pupil narrows, which ensures clarity of the image on the retina. If accommodation is disturbed, a person loses the ability to see the clear contours of objects at different distances from the eye.

The fibers of the peripheral motor neuron of the oculomotor nerve begin from the cells of the above nuclei and exit the legs of the brain on their medial surface, then pierce the dura mater and then follow in the outer wall of the cavernous sinus. The oculomotor nerve leaves the skull through the superior orbital fissure and enters the orbit.

Block nerve (4th)

The nuclei of the trochlear nerves are located at the level of the inferior colliculus of the roof of the midbrain anterior to the central gray matter, below the nuclei of the oculomotor nerve. The internal nerve roots envelop the outer part of the central gray matter and cross in the superior medullary velum, which is a thin plate that forms the roof of the rostral part of the fourth ventricle. After decussation, the nerves leave the midbrain downward from the inferior hillocks. The trochlear nerve is the only nerve that emerges from the dorsal surface of the brainstem. On the way in the central direction to the cavernous sinus, the nerves first pass through the coracoid cerebellopontine fissure, then through the notch of the cerebellum tenon, and then along the outer wall of the cavernous sinus, and from there, together with the oculomotor nerve, they enter the orbit through the superior orbital fissure.

The trochlear nerve innervates the superior oblique muscle, which rotates the eyeball outwards and downwards. Paralysis of the muscle causes the affected eyeball to deviate upward and somewhat inwards. This deviation is especially noticeable when the affected eye looks down and to the healthy side. There is double vision when looking down; it is clearly manifested if the patient looks at his feet, in particular when walking up the stairs.

Abducens nerve (6th)

The abducens nerve innervates the lateral rectus muscle. The nucleus of the abducens nerve also contains neurons that, through the medial longitudinal bundle, are connected with the nucleus of the oculomotor nerve, which innervates the medial rectus muscle from the opposite side; therefore, the symptoms of damage to the nuclei and the nerve itself are different.

The VI (abducens) nerve has a single motor (GSE) nucleus. It lies in the pons, and is responsible for the innervation of the rectus eye muscle, which takes the eye to the side.

Accessory nerve (11th)

Accessory (11th cranial nerve) innervates the sternocleidomastoid and trapezius muscles.

The XI (accessory) nerve combines information from two nuclei. The first motor nucleus (GSE) lies in the cervical spinal cord, and is responsible for the innervation of the trapezius and sternocleidomastoid muscles (neck muscles). The second nucleus, information from which goes to three nerves (IX, X, XI), a dual nucleus (nucleus ambigous), motor (SVE - specific visceral efferent) - is located in the medulla oblongata just below the olives and lateral to the nucleus of the hypoglossal nerve, innervates the larynx.

Hypoglossal nerve (12th)

Hyoid (12th cranial nerve) innervates the muscles of the tongue. The hypoglossal nerve innervates the muscles of the ipsilateral half of the tongue, as well as the geniohyoid, thyroid-hyoid, scapular-hyoid, and sternothyroid muscles.

This nerve includes nerve fibers extending from the neurons of the motor nucleus located in the medulla oblongata. It leaves the cranial cavity through the canal of the hyoid nerve in the occipital bone, follows, describing an arc, to the tongue from below and is divided into branches that innervate all the muscles of the tongue and the geniohyoid muscle. One of the branches of the hypoglossal nerve (descending) forms, together with the branches of the I-III cervical nerves, the so-called cervical loop. The branches of this loop (due to fibers from the cervical spinal nerves) innervate the muscles of the neck, which lie below the hyoid bone.

Lecture 5 Cranial nerves

Functions of the twelve pairs of cranial nerves

In ordinary life, a person very rarely thinks about how many nerves are in his body. Only when he falls ill or is injured does he begin to realize how important a role nerves play in the normal functioning of various organs and the whole organism.

The sense organs play an enormous role in human life. Without sight, smell, touch, hearing, and the ability to experience different tastes, life loses some of its charm and becomes difficult and dangerous. Most of the human senses are controlled by 12 pairs of cranial nerves.

Classification of cranial nerves

12 pairs of cranial nerves depart from the brain stem, in the international classification they are often referred to as cranial. Each pair has its own name and is indicated by Roman letters. Some sources consider the intermediate nerve to be the thirteenth pair, but this concept has not been approved by world experts.

• | para - olfactory nerve.
• || pair - optic nerve.
• ||| pair - oculomotor nerve.
• | V pair - trochlear nerve.
• V pair - trigeminal nerve.
• v| para - abducens nerve.
• V|| pair - facial nerve.
• V||| pair - vestibulocochlear nerve.
• | X pair - glossopharyngeal nerve.
• X pair - vagus nerve.
• X| pair - accessory nerve.
• X|| pair - hypoglossal nerve.

Functions of the cranial nerves

Each of the 12 pairs of cranial nerves is responsible for performing certain actions that provide different stages of human perception of the surrounding reality.

Each of the 12 pairs of cranial nerves, controlling its narrow area of ​​work, generally provides a person with the ability to see, hear, smell, taste, and also respond to what is happening. This complex system can be compared to an orchestra, where each instrument plays its own part, all together creating a harmonious and beautiful melody.

Cranial nerves and their nuclei

12 pairs of cranial nerves depart from the GM:

I. Olfactory nerve - n. (nervus) olfactorius;

II. optic nerve - n. opticus;

III. oculomotor nerve - n. oculomotorius;

IV. Block nerve - n. trochlearis;

V. Trigeminal nerve - n. trigeminus;

VI. abducens nerve - n. abducens;

VII. Facial nerve - n.facialis;

VII. Vestibulo-auditory nerve - n. vestibulocochlearis;

IX. Glossopharyngeal nerve - n. glossopharyngeus;

X. Vagus nerve - n. vagus;

XI. Accessory nerve - n. accessorius;

XII. hypoglossal nerve - n. hypoglossus.

Unlike mixed (consisting of afferent sensory and efferent motor and autonomic fibers) spinal nerves among the cranial nerves, there are both mixed and only afferent or only efferent.

Only afferent (sensory) nerves are I, II and VIII pairs. Only efferent nerves - III, IV, VI, XI and XII pairs. The remaining four pairs (V, VII, IX and X) are mixed. The first two pairs (olfactory and optic nerves) are fundamentally different in nature and origin from the rest of the nerves. They are outgrowths of the forebrain.

Let us characterize the remaining ten pairs of cranial nerves. They all originate from the brain stem. III and IV - from the midbrain; V- from the pons; VI, VII and VIII - from the groove between the pons and the medulla oblongata; IX, X, XI and XII - from the medulla oblongata. All nerves, with the exception of IV, exit the brain on the ventral (front) side. The fourth nerve exits on the dorsal side, but immediately goes around the brainstem and passes to the ventral side.

The neurons whose processes form the cranial nerves are similar to the neurons that form the spinal nerves. Next to the GM lie cranial ganglia, similar to the spinal ones. They contain sensory neurons. Their peripheral processes form sensory fibers of mixed nerves. The central processes enter the GM and terminate at the nuclei in the brainstem. Such nuclei are called sensory nuclei of the cranial nerves. Their cells are similar to the intercalary neurons of the posterior horns of the SM. Also in the brainstem are nuclei, from the neurons of which axons depart, forming efferent fibers. They are of two types. If the fibers from these nuclei go to the skeletal (voluntary) muscles, this somatic-motor kernels. They belong to the somatic NS. Their neurons are similar to the motor neurons of the anterior horns of the spinal cord. If the fibers from these nuclei end in the autonomic ganglia, such nuclei are called vegetative. Their neurons are similar to the central autonomic neurons that lie in the intermediate substance of the SM. All autonomic neurons of the brain stem belong to the parasympathetic part of the ANS (see Chapter 8).

So, depending on which fibers form the nerve, the latter may have one, two or more nuclei (Fig. 22). Most of these nuclei (nucleus V - XII nerves) lie in the thickness of the medulla oblongata and the bridge. In the drawings, it is customary to project them onto the bottom of the IV ventricle - a rhomboid fossa (see 4.2). The nuclei of the III and IV nerves are located in the midbrain.

Rice. 22. Nuclei of cranial nerves and exit of nerves from the brain stem:

1 - motor and 2- autonomic nucleus of the oculomotor

nerve;.3 - red core; four- motor nucleus of the trochlear nerve;

5 - nuclei of the trigeminal nerve (marked with dots); b- motor

nucleus of the abducens nerve; 7- motor nucleus of the facial nerve;

8 - autonomic nuclei of the facial and glossopharyngeal nerves; 9- double

nucleus; ten- vegetative nucleus of the vagus nerve; eleven- motor

nucleus of the accessory nerve; 12- motor nucleus of the hyoid

nerve; 13- olive kernel. Solitary path core and sensitive

the nuclei of the vestibulo-auditory nerve are not shown in this figure

Efferent cranial nerves. Oculomotor (III pair), blocky(IV pair) and diverting(VI pair) nerves control eye movements. Each of these nerves has a somatic motor nucleus, fibers from which go to the muscles of the eye. The oculomotor nerve innervates the superior, inferior, and internal rectus muscles, as well as the inferior oblique muscle of the eye; block - the upper oblique muscle of the eye; abductor - external rectus muscle of the eye. The nuclei of the III and IV nerves are located in the midbrain, the nucleus of the VI nerve is in the bridge under the facial tubercle in the rhomboid fossa (see 7.2.4). The oculomotor nerve has another nucleus - autonomic. It gives parasympathetic fibers, along which impulses go, reducing the diameter of the pupil and regulating the curvature of the lens. Between the nuclei of these three pairs of nerves, there are close mutual connections, due to which combined eye movements and image stabilization on the retina are achieved.

accessory nerve(XI pair) controls the muscles of the larynx, as well as the sternocleidomastoid muscle of the neck and the trapezius muscle of the shoulder girdle. The nucleus is located in the medulla oblongata, part of it is extended into the spinal cord.

hypoglossal nerve(XII pair). Innervates the muscles of the tongue and controls its movements. The nucleus of this nerve stretches almost through the entire medulla oblongata.

Mixed cranial nerves.Trigeminal nerve(V pair) contains afferent and efferent somatic-motor fibers. Sensitive fibers innervate the skin of the face, teeth, mucous membranes of the oral and nasal cavities, carrying out pain, temperature, skin and muscle sensitivity.

Examination of the cranial nerves

Motor fibers control the chewing muscles and some muscles of the middle ear.

The trigeminal nerve has three sensory nuclei, two of which are in the medulla oblongata and pons, and one in the midbrain. The only motor nucleus of this nerve is located in the bridge.

The name "trigeminal" is due to the fact that it consists of three branches that carry information from the three "floors" of the face - the forehead; nose, cheeks and upper jaw; lower jaw. The motor fibers run in the inferior branch of the trigeminal nerve.

facial nerve(VII pair) contains three types of fibers:

1) afferent sensory fibers bring impulses from the taste buds of the anterior two-thirds of the tongue. These fibers terminate in the nucleus of the solitary tract, the common sensory nucleus of the facial, glossopharyngeal, and vagus nerves. It is extended from the medulla oblongata to the pons;

2) somatic-motor fibers innervate the facial muscles, as well as the muscles of the eyelids, some muscles of the ear. These fibers come from the motor nucleus located in the bridge;

3) autonomic parasympathetic fibers of the facial nerve innervate the submandibular and sublingual salivary glands, lacrimal glands, glands of the nasal mucosa. They originate from the parasympathetic superior salivary nucleus, also located in the pons.

Glossopharyngeal nerve(IX pair) is similar in composition to the facial nerve, i.e. also contains three types of fibers:

1) afferent fibers bring information from the receptors of the posterior third of the tongue and terminate on the neurons of the nucleus of the solitary pathway;

2) efferent somatic-motor fibers innervate some muscles of the pharynx and larynx. The fibers begin in the double nucleus - a common motor nucleus for the glossopharyngeal and vagus nerves, located in the medulla oblongata;

3) efferent parasympathetic fibers originate in the inferior salivary nucleus and innervate near the ear salivary gland.

Nervus vagus(X pair) is so called because of the vastness of the distribution of its fibers. It is the longest of the cranial nerves; With its branches, it innervates the respiratory organs, a significant part of the digestive tract, and the heart. Latin name for this nerve n. vagus, hence it is often referred to as vagus.

Just like the VII and IX nerves, the vagus contains three types of fibers:

1) afferent ones carry information from the receptors of the previously named internal organs and vessels of the chest and abdominal cavity, as well as from the hard shell of the brain and the external auditory canal with the auricle. Information about the depth of breathing, pressure in blood vessels, stretching of the walls of organs, etc. comes through these fibers. They end in the core of a solitary path;

2) efferent somatic-motor innervates the muscles of the pharynx, soft palate, larynx (including those controlling the tension of the vocal cords). Fibers start in a double core;

3) efferent parasympathetic fibers start from the parasympathetic nucleus of the vagus nerve in the medulla oblongata. The parasympathetic part of the vagus nerve is very large, so it is predominantly an autonomic nerve.

From sensory cranial nerves only the vestibulo-auditory nerve (VIII pair) departs from the brain stem. It brings impulses from the auditory and vestibular receptors of the inner ear to the CNS. The sensory nuclei of this nerve - two auditory (ventral and dorsal) and four vestibular (lateral, medial, superior and inferior) - are located on the border of the medulla oblongata and the pons in the region of the vestibular field (see 7.2.2).

Nerve VIII originates in the inner ear and consists of two separate nerves, the cochlear (auditory) nerve and the vestibular (vestibular) nerve.

In conclusion, it should be noted that the nuclei of the cranial nerves have many afferents and efferents. So, all sensitive nuclei send efferents to the thalamus (interbrain), and from there information enters the cerebral cortex. In addition, sensory nuclei transmit signals to the reticular formation of the brainstem (see 7.2.6). All motor nuclei receive afferents from the cerebral cortex as part of the corticonuclear tract (see 6.4). Finally, there are numerous connections between the nuclei of the cranial nerves themselves, which facilitates the coordinated activity of various organs. In particular, due to the connections between the sensory and motor nuclei, the arcs of stem unconditioned reflexes (for example, vomiting, blinking, salivation, etc.) are closed, similar to spinal unconditioned reflexes.