What is located in the middle part of the ear? Ear: outer, middle, inner. Auditory pathway The middle ear includes the following elements

A person receives most of the information about the world around him through sight and hearing. Moreover, the structure of the ear is very complex. Any disturbance in the middle ear or other parts of the hearing aid can lead not only to hearing loss, but also to the creation of a situation where a person's life is in danger. Let's figure out what are the functions and structure of the middle ear, what diseases affect this part of the hearing aid and how to prevent their occurrence.

The middle ear is located between the inner and outer. The main purpose of this part of the hearing aid is to conduct sounds. The middle ear consists of the following parts:

1. Auditory ossicles. They are stirrup, hammer and anvil. It is these details that help to transmit sounds, and distinguish them by strength and height. The peculiarities of the work of the auditory ossicles help to protect the hearing aid from sharp and loud sounds.
2. auditory tube. This is the passage that connects the nasopharynx with the tympanic cavity. Its mouth is closed when a person swallows or sucks something. In newly born children, for some time the auditory tube is wider and shorter than in adulthood.
3. drum cavity. It is this part of the middle ear that contains the auditory ossicles described above. The location of the tympanic cavity is the area between the outer ear and the temporal bone.
4. Mastoid. This is the convex part of the temporal bone. It contains cavities that are filled with air and communicate with each other through narrow holes.

The middle ear is an apparatus that conducts sound vibrations, consisting of air cavities and complex anatomical structures. The tympanic cavity is lined with mucous membrane and separated from the rest of the skull by the upper wall. All auditory ossicles are also covered with mucous. The middle and inner ear are separated by a bony wall. They are connected by only two holes:

• round window;
• oval window in the ear.

Each of them is protected by a flexible and elastic membrane. The stirrup, one of the auditory ossicles, enters the oval window in front of the water-filled inner ear.

Important! Also in the work of this part of the hearing aid, a huge role is assigned to the muscles. There is a muscle that controls the eardrum and a group of muscles that controls the auditory ossicles.

Middle ear functions

Air cavities and other anatomical structures located in the middle ear provide sound permeability. The main functions of the middle ear are:

• maintaining the health of the eardrum;
• transmission of sound vibrations;
• protection of the inner ear from harsh and too loud sounds;
• ensuring the susceptibility of sounds of different strength, height and loudness.

Important! The main function of the middle ear is to conduct sounds. And any disease or injury that affects this part of the hearing aid can lead to permanent total or partial hearing loss.

Diseases of the middle ear

The main symptoms of the occurrence of problems in the middle ear, experts call the following signs and conditions of a person:

• pain in the ear area of ​​varying intensity (mostly very strong);
• feeling of congestion;
• reduction or complete loss of hearing;
• discharge of fluid or pus from the ear canal;
• increased body temperature;
• decreased appetite and poor sleep;
• change in the color of the eardrum to more red.

Among the most common diseases of the middle ear, it is worth noting the following:

1. Purulent otitis media. This is inflammation, in which purulent and purulent-bloody discharge from the ear canal is observed, a person complains of unbearable pain, and hearing is significantly impaired. The disease affects the middle ear cavity and the tympanic membrane, and can spread to other parts of the hearing aid.
2. Cicatricial otitis. In this case, the inflammatory process led to the formation of scars and a decrease in the mobility of the auditory ossicles. Because of this, there is a strong hearing loss.
3. Mesotympanitis. The disease is similar in symptoms to purulent otitis media. In this case, the eardrum is affected, and the person notes hearing loss and purulent discharge.
4. Epidemic. In the course of this disease, inflammation of the epitympanic space of the middle ear occurs, a prolonged course of the inflammatory process can disrupt the structure of the middle and inner ear, which will lead to a decrease and a sharp deterioration in hearing.
5. Mastoiditis. Most often, this is a consequence of purulent otitis media not treated correctly and in a timely manner, which affects not only the middle ear, but also the mastoid process.
6. Middle ear catarrh. The disease usually precedes purulent otitis and affects the auditory tube.
7. Bullous otitis. The disease occurs against the background of the flu and has symptoms similar to other otitis media. The focus of the inflammatory process is located in the epitympanic air cavity.

Important! Often problems with the middle ear can occur against the background of various diseases of an infectious nature, for example, tonsillitis, sinusitis, rhinitis, laryngitis, influenza. Also, improper care of the ears and nose, injuries, water entering the ear canal, hypothermia and drafts are also common causes.

Prevention of diseases of the middle ear

Wear a hat in winter

As a preventive measure for the development of diseases of the middle ear, experts recommend that children and adults adhere to the following rules:

1. Timely treat diseases of the upper respiratory tract, nose and ears. Infection with improperly selected treatment or its absence quickly spreads from the nasopharynx or outer ear further than it disrupts the functioning of the hearing aid. Always follow the recommendations of doctors during the treatment of diseases of the ENT organs. Do not stop therapy, even if you feel great, do not change the dosage and regimen of drugs, do not prolong the period of their use.
2. If a person has congenital anomalies in the structure of the ear, then they should be solved with the help of a specialist, if possible. Sometimes it is necessary to perform an operation, and in some cases it is enough to take certain medications.
3. Hygiene. The accumulation of wax, dirt or water in the ear canal can lead to inflammation. Therefore, try to clean your ears and your children in a timely manner with cotton turundas. When swimming or bathing, use special caps and earplugs, avoid getting a direct stream of water into the ear canal.
4. Make sure your ears are not injured. The ingress of a foreign body, the use of sharp and hard objects when cleaning the ears, as well as some other reasons, can cause inflammation and provoke an infection in the middle ear.
5. Wear a hat in winter. Protect yourself from drafts and hypothermia, sudden changes in temperature and humidity. For small children, it is best to wear special thin caps, even if the room temperature is comfortable.
6. In childhood, as a preventive measure for frequently occurring otitis media and other inflammatory processes due to overgrown or greatly enlarged adenoids, their removal is sometimes recommended.

Important! The best prevention of diseases of the middle ear is to strengthen the immune system. A balanced diet, moderate physical activity, hardening - all this will increase the body's endurance and resistance to infections and significantly reduce the risk of developing diseases.

Remember, diseases of the middle ear are very dangerous for hearing and human life. In case of any disturbing symptoms, you should immediately consult a doctor. It is impossible to self-medicate with otitis media and other inflammatory processes either in childhood or in adulthood. This can lead to serious complications, including the spread of the infection beyond the middle ear, its penetration into the brain, as well as reduction and complete loss of hearing. The sooner you see a doctor and start treatment, the lower the risk of complications and the higher the chance to eliminate the disease as soon as possible without any consequences.

The middle ear (auris media) consists of several interconnected air cavities: the tympanic cavity (cavum tympani), the auditory tube (tuba auditiva), the entrance to the cave (aditus ad antrum), the cave (antrum) and the associated air cells of the mastoid process. (cellulae mastoidea). Through the auditory tube, the middle ear communicates with the nasopharynx; under normal conditions, this is the only communication of all cavities of the middle ear with the external environment.

Rice. 4.4.

1 - horizontal semicircular canal; 2 - canal of the facial nerve; 3 - roof of the tympanic cavity; 4 - vestibule window; 5 - semi-channel of the muscle; 6 - tympanic opening of the auditory tube; 7 - canal of the carotid artery; 8 - promontorium; 9 - tympanic nerve; 10 - jugular fossa; 11 - snail window; 12 - drum string; 13 - pyramidal process; 14 - the entrance to the cave.

Tympanic cavity (Fig. 4.4). The tympanic cavity can be compared to an irregularly shaped cube up to 1 cm3 in volume. It distinguishes six walls: upper, lower, anterior, posterior, outer and inner.

The upper wall, or roof, of the tympanic cavity (tegmen tympani) is represented by a bone plate 1-6 mm thick. It separates the tympanic cavity from the middle cranial fossa. There are small openings in the roof through which vessels pass, carrying blood from the dura mater to the mucous membrane of the middle ear. Sometimes dehiscences form in the upper wall; in these cases, the mucous membrane of the tympanic cavity is directly adjacent to the dura mater.

In newborns and children of the first years of life, on the border between the pyramid and the scales of the temporal bone, there is an open gap (fissura petrosquamosa), which causes the occurrence of brain symptoms in them with acute inflammation of the middle ear. Subsequently, a suture (sutura petrosquamosa) is formed at this place and communication with the cranial cavity in this place is eliminated.

The lower (jugular) wall, or the bottom of the tympanic cavity (paries jugularis), borders on the jugular fossa (fossa jugularis) lying under it, in which the bulb of the jugular vein (bulbus venae jugularis). The more the fossa protrudes into the tympanic cavity, the thinner the bone wall. The inferior wall may be very thin or have dehiscences through which the bulb of the vein sometimes protrudes into the tympanic cavity. This makes it possible to injure the bulb of the jugular vein, accompanied by severe bleeding, during paracentesis or careless scraping of granulations from the bottom of the tympanic cavity.

The anterior wall, tubal or carotid (paries tubaria, s.caroticus), of the tympanic cavity is formed by a thin bone plate, outside of which the internal carotid artery is located. There are two openings in the anterior wall, the upper one, narrow, leads to the semi-canal for the muscle that stretches the eardrum (semicanalis m.tensoris tympani), and the lower, wide one, to the tympanic mouth of the auditory tube (ostium tympanicum tybae auditivae). In addition, the anterior wall is permeated with thin tubules (canaliculi caroticotympanici), through which vessels and nerves pass into the tympanic cavity, in some cases it has dehiscences.

The posterior (mastoid) wall of the tympanic cavity (paries mastoideus) borders on the mastoid process. In the upper part of this wall there is a wide passage (aditus adantrum), which connects the epitympanic recess - attic (attic) with a permanent cell of the mastoid process - a cave (antrum mastoideum). Below this passage is a bone protrusion - a pyramidal process, from which the stirrup muscle (m.stapedius) begins. On the outer surface of the pyramidal process is the tympanic foramen (apertura tympanica canaliculi chordae), through which the tympanic string (chorda tympani), which departs from the facial nerve, enters the tympanic cavity. In the thickness of the lower section of the posterior wall, the descending knee of the facial nerve canal passes.

The outer (membranous) wall of the tympanic cavity (paries membranaceus) is formed by the tympanic membrane and partly in the attic region by a bone plate that extends from the upper bone walls of the external auditory canal.

Internal (labyrinth, medial, promontory ) the wall of the tympanic cavity (paries labyrinthicus) is the outer wall of the labyrinth and separates it from the cavity of the middle ear. In the middle part of this wall there is an oval-shaped elevation - a cape (promontorium), formed by a protrusion of the main volute of the snail.

Behind and above the promontory there is a niche of the vestibule window (an oval window according to the old nomenclature; fenestra vestibuli), closed by the base of the stirrup (basis stapedis). The latter is attached to the edges of the window by means of an annular ligament (lig. annulare). In the direction backwards and downwards from the cape, there is another niche, at the bottom of which there is a cochlea window (a round window according to the old nomenclature; fenestra cochleae), leading to the cochlea and closed by a secondary tympanic membrane (membrana ympany secundaria), which consists of three layers: outer - mucous, middle - connective tissue and internal - endothelial.

Above the window of the vestibule along the inner wall of the tympanic cavity in the direction from front to back, the horizontal knee of the bone canal of the facial nerve passes, which, having reached the protrusion of the horizontal semicircular canal on the inner wall of the antrum, turns vertically down-descending knee - and goes to the base of the skull through the stylomastoid foramen (for. stylomastoideum). The facial nerve is located in the bone canal (canalis Fallopii). The horizontal segment of the canal of the facial nerve above the window of the vestibule protrudes into the tympanic cavity in the form of a bone roller (prominentia canalis facialis). Here it has a very thin wall, in which there are often dehiscences, which contributes to the spread of inflammation from the middle ear to the nerve and the occurrence of paralysis of the facial nerve. An otolaryngologist surgeon sometimes has to deal with various variants and anomalies in the location of the facial nerve, both in its tympanic and mastoid regions.

In the middle floor of the tympanic cavity, the chorda tympani departs from the facial nerve. It passes between the malleus and the incus through the entire tympanic cavity near the tympanic membrane and exits it through the stony-tympanic (glazer) fissure (fissura petrotympanica, s.Glaseri), giving taste fibers to the tongue on its side, secretory fibers to the salivary gland and fibers to the vascular plexus.

The tympanic cavity is conditionally divided into three sections, or floors: the upper one is the attic, or epitympanum (epitympanum), located above the upper edge of the stretched part of the tympanic membrane, the height of the attic varies from 3 to 6 mm. The articulation of the malleus with the anvil enclosed in it divides the attic into external and internal sections. The lower part of the outer part of the attic is called the "superior recess of the tympanic membrane", or "Prussian space", posteriorly, the attic passes into the antrum; medium - the largest in size (mesotympanum), corresponds to the location of the stretched part of the eardrum; lower (hypotympanum) - a depression below the level of attachment of the tympanic membrane (Fig. 4.5, a, b).

A - sagittal section: 1 - upper ligament of the anvil; 2 - short leg of the anvil; 3 - cave; 4 - posterior ligament of the anvil; 5 - long leg of the anvil; 6 - posterior malleus fold; 7 - back pocket of the membrane; 8 - lenticular process of the incus; 9 - hammer handle; 10 - canal of the facial nerve; 11 - drum string; 12 - facial nerve; 13 - drum ring; 14 - stretched part of the eardrum; 15- auditory tube; 16 - anterior malleus fold, 17 - anterior pocket of the membrane; eighteen - ; 19 - head of the malleus; 20 - upper ligament of the malleus; 21 - anvil-hammer joint.

The mucous membrane of the tympanic cavity is a continuation of the mucous membrane of the nasopharynx (through the auditory tube); it covers the walls of the tympanic cavity, the auditory ossicles and their ligaments, forming a series of folds and pockets. Tightly adhering to the bone walls, the mucous membrane is for them at the same time the periosteum (mucoperiostum). It is covered mainly by squamous epithelium, with the exception of the mouth of the auditory tube,

Rice. 4.5. Continuation.

: 22 - anterior semicircular canal; 23 - posterior semicircular canal; 24 - lateral semicircular canal; 25 - tendon of the stirrup muscle; 26 - VIII cranial (vestibulocochlear) nerve; 27 - probe in the window of the cochlea; 28 - snail; 29 - muscle straining the eardrum; 30 - sleepy channel; 31 - stirrup; 32 - anterior process of the malleus; 33 - upper pocket of the tympanic membrane (Prussian space); 34 - lateral ligament of the malleus.

Where there is ciliated columnar epithelium. Glands are found in some places of the mucous membrane.

The auditory ossicles - the malleus (malleus), the anvil (incus) and the stirrup (stapes) - are connected by joints, anatomically and functionally represent a single chain (Fig. 4.6), which stretches from the tympanic membrane to the window of the vestibule. The handle of the malleus is woven into the fibrous layer of the tympanic membrane, the base of the stirrup is fixed in the niche of the vestibule window. The main mass of the auditory ossicles - the head and neck of the malleus, the body of the anvil - is located in the epitympanic space (see Fig. 4.5, b). The auditory ossicles are reinforced with each other and with the walls of the tympanic cavity with the help of elastic ligaments, which ensures their free displacement when the tympanic membrane fluctuates.

1 - anvil; 2 - long leg of the anvil; 3 - anvil-staple joint; 4 - stirrup; 5 - rear leg of the stirrup; 6 - stirrup base; 7- front leg of the stirrup; 8 - hammer handle; 9 - anterior process of the malleus; 10 - hammer; 11 - head of the malleus; 12 - anvil-hammer joint; 13 - a short process of the anvil; 14 - the body of the anvil.

The malleus is divided into a handle, a neck and a head. At the base of the handle is a short process that protrudes outwards from the eardrum. The mass of the malleus is about 30 mg.

The anvil consists of a body, a short process and a long process articulated with the stirrup. The mass of the anvil is about 27 mg.

The stirrup has a head, two legs and a base.

The annular ligament, with which the base of the stirrup is attached to the edge of the vestibule window, is sufficiently elastic and provides good oscillatory mobility of the stirrup. In the anterior section, this ligament is wider than in the posterior one; therefore, during the transmission of sound vibrations, the base of the stirrup is displaced mainly by its anterior pole.

The stirrup is the smallest of the auditory ossicles; its mass is about 2.5 mg with a base area of ​​3-3.5 mm2.

The muscular apparatus of the tympanic cavity is represented by two muscles: tensile tympanic membrane (m.tensor tympani) and stirrup (m. stapedius). Both of these muscles, on the one hand, hold the auditory ossicles in a certain position, the most favorable for conducting sound, on the other hand, they protect the inner ear from excessive sound stimulation by reflex contraction. The muscle stretching the tympanic membrane is attached at one end in the region of the opening of the auditory tube, with the other - to the handle of the malleus near the neck. It is innervated by the mandibular branch of the trigeminal nerve through the ear ganglion; the stirrup muscle starts from the pyramidal protrusion and is attached to the neck of the stirrup; innervated by the stapedial nerve (n.stapedius) branch of the facial nerve.

Auditory (e in stakh and e in a) tube and, as already noted, is a formation through which the tympanic cavity communicates with the external environment: it opens in the nasopharynx. The auditory tube consists of two parts: a short bone - 1L canal (pars ossea) and a long cartilage - 2/3 (pars cartilaginea). Its length in adults is on average 3.5 cm, in newborns - 2 cm.

At the point of transition of the cartilaginous part into the bone, an isthmus (isthmus) is formed - the narrowest place (diameter 1-1.5 mm); it is located approximately 24 mm from the pharyngeal opening of the tube. The lumen of the bony part of the auditory tube in the section is a kind of triangle, and in the membranous-cartilaginous section, the walls of the tube are adjacent to each other.

The internal carotid artery passes medially to the bony part of the tube. It should be borne in mind that in the membranous-cartilaginous part, the lower and anterior walls of the tube are represented only by fibrous tissue. The pharyngeal opening of the auditory tube is 2 times wider than the tympanic one and is located 1-2.5 cm below it on the side wall of the nasopharynx at the level of the posterior end of the inferior turbinate.

Blood supply to the tympanic cavity is carried out from the pools of the external and partially internal carotid arteries: the anterior, tympanic artery, which departs from the maxillary; posterior auricular artery, arising from the stylomastoid artery and anastomosing with the middle meningeal artery. Branches depart from the internal carotid artery to the anterior parts of the tympanic cavity.

The venous outflow from the tympanic cavity occurs mainly along the veins of the same name.

Lymphatic drainage from the tympanic cavity follows along the mucous membrane of the auditory tube to the retropharyngeal lymph nodes.

And the innervation of the tympanic cavity occurs due to the tympanic nerve (n.tympanicus) from the IX pair (n.glossopharyngeus) of the cranial nerves. Having entered the tympanic cavity, the tympanic nerve and its branches anastomose on the inner wall with branches of the facial nerve, trigeminal and sympathetic plexuses of the internal carotid artery, forming the cape tympanic plexus (plexus tympanicus s.Jacobsoni).

Sostsevidny process (prosessus mastoideus).

In a newborn, the mastoid part of the middle ear looks like a small elevation behind the upper posterior edge of the tympanic ring, containing only one cavity - the antrum (cave). Starting from the 2nd year, this eminence is extended downward due to the development of the muscles of the neck and occiput. The formation of the process ends mainly by the end of the 6th - the beginning of the 7th year of life.

The mastoid process of an adult resembles a cone, overturned by the tip - a ledge. The internal structure of the mastoid process is not the same and depends mainly on the formation of air cavities. This process occurs by replacing bone marrow tissue with ingrown epithelium. As the bone grows, the number of air cells increases. According to the nature of pneumatization, one should distinguish: 1) pneumatic type of structure of the mastoid process, when the number of air cells is large enough. They fill almost the entire process and sometimes even extend to the scales of the temporal bone, the pyramid, the bone part of the auditory tube, and the zygomatic process; 2) diploetic (spongy, spongy) type of structure. In this case, the number of air cells is small, they look like small cavities, limited by trabeculae, and are located mainly near the cave; 3) sclerotic (compact) type of structure: the mastoid process is formed by exceptionally dense bone tissue.

If the pneumatic type of structure of the mastoid process is observed during the normal development of the child, then diploetic and sclerotic are sometimes the result of metabolic disorders or the result of general and local inflammatory diseases, etc. There is an opinion that some genetic or constitutional factors, as well as the resistance and organ-tissue reactivity associated with them, have a certain influence on the process of pneumatization of the mastoid process.

The anatomical structure of the mastoid process is such that all its air cells, regardless of their distribution and location, communicate with each other and with the cave, which, through aditus ad antrum, communicates with the epitympanic space of the tympanic cavity. The cave is the only congenital air cavity; its development does not depend on the type of structure of the mastoid process.

In infants, unlike adults, it is much larger in volume and is located quite close to the outer surface. In adults, the cave lies at a depth of 2-2.5 cm from the outer surface of the mastoid process. The dimensions of the mastoid process in adults range from 9-15 mm in length, 5-8 mm in width and 4-18 mm in height. In a newborn, the dimensions of the cave are the same. From the dura mater of the middle cranial fossa, the cave is separated by a bone plate (tegmen antri), when destroyed by a purulent process, inflammation can pass to the meninges.

The dura mater of the posterior cranial fossa is separated from the cavity of the mastoid process by the Trautmann triangle, which is located posteriorly from the facial nerve to the sigmoid sinus. The mucous membrane lining the cave and air cells is a continuation of the mucous membrane of the tympanic cavity.

On the inner back surface (from the side of the cranial cavity) of the mastoid process there is a recess in the form of a gutter. It contains the sigmoid venous sinus (sinus sigmoideus), through which the outflow of venous blood from the brain to the jugular vein system is carried out. The dura mater of the posterior cranial fossa is delimited from the cellular system of the mastoid process by means of a thin but rather dense bone plate (lamina vitrea). In some cases, purulent inflammation of the cells can lead to the destruction of this plate and the penetration of infection into the venous sinus. Sometimes a mastoid injury can break the integrity of the sinus wall and lead to life-threatening bleeding. Near the cells of the mastoid process is the mastoid part of the facial nerve. This neighborhood sometimes explains paralysis and paresis of the facial nerve in acute and chronic inflammation of the middle ear.

Outside, the mastoid process has a compact bone-cortical layer, the surface of which is rough, especially in the lower section, where the sternocleidomastoid muscle (m.sternocleidomastoideus) is attached. On the inner side of the apex of the appendix there is a deep groove (incisura mastoidea), where the digastric muscle (m.digastricus) is attached. Through this groove, pus sometimes breaks from the cells of the appendage under the cervical muscles. Within the outer surface of the mastoid process there is a smooth triangular area, called the Shipo triangle. In the anterior upper corner of this triangle there is a fossa in the form of a platform (planum mastoidea) and a comb (spina suprameatum), which correspond to the outer wall of the antrum. In this area, bone trepanation is performed in search of a cave with mastoiditis in adults and anthritis in children.

The blood supply to the mastoid region is carried out from the posterior auricular artery (a.auricularis posterior - a branch of the external carotid artery - a.carotis externa). Venous outflow occurs in the vein of the same name, which flows into the external jugular vein (v.jugularis externa).

Innervation of the mastoid region is provided by sensory nerves from the superior cervical plexus, the large ear (n.auricularis magnus) and the small occipital (n.oscipitalis minor). The motor nerve for the rudimentary behind the ear muscle (m.auricularis posterior) is the branch of the facial nerve of the same name.

The human ear has a very complex anatomical structure that allows you to pick up sound waves, determine the direction of the sound source and correctly identify it. It consists of three main sections: the outer, middle and inner ear. Each of which has strictly defined functions and a special structure. The human middle ear primarily converts sound waves into nerve impulses. This is its main, but not the only function.

General structure and principle of operation

The middle ear begins immediately behind the tympanic membrane, located at the end of the auditory canal and separating it from the outer ear. The middle ear consists of three main elements:

• tympanic cavity;
• mastoid processes;
• auditory tube.

The tympanic membrane is a small patch of thin connective tissue that is directly involved in the transformation of sound waves picked up by the outer ear.

The tympanic cavity of the middle ear is located in the notch of the temporal bone. Inside it, in close proximity, are the three smallest bones of the human skeleton: the hammer, stirrup and anvil. Acoustic waves cause the eardrum to vibrate, and these vibrations are transmitted to the bones. And the stirrup through the oval window sends a signal to the fluid that fills the inner ear - the perilymph.

Interestingly, the design of the auditory ossicles allows not only to transmit, but also to significantly amplify sound. The surface of the stirrup is an order of magnitude smaller than the area of ​​the tympanic membrane, which means that it hits the oval window much harder, giving a person the opportunity to hear even very quiet sounds.

Protective functions of the middle ear

The functions of the middle ear are not limited to sound conduction. It is also a reliable protective barrier protecting the delicate inner ear from:

• ingress of moisture, particles of dust and dirt;
• penetration and reproduction of pathogenic microorganisms;
• too intense exposure to a sound wave;
• sudden changes in atmospheric pressure;
• mechanical impact.

The middle ear cavity is filled with air and is connected to the nasopharynx by the Eustachian tube. Under normal conditions, air pressure is the same on both sides of the eardrum. But if atmospheric pressure changes sharply in any direction, then this stretches the eardrum and can lead to its rupture.

This phenomenon is called barotrauma. The same thing happens with a sharp dive to a great depth. Dive slowly to prevent barotrauma. And when taking off or landing an airplane, open your mouth or make swallowing movements often.

The anatomy of the middle ear allows for partial compensation of loud sounds. It houses two very small muscles, one of which controls the tension of the tympanic membrane, and the other controls the amplitude of the stirrup vibration. A protective mechanism laid down by nature provides a reflex contraction of these muscles when sounds are too loud. The movement of the stirrup is limited and the sensitivity of the ear is temporarily reduced. It takes about 10ms to trigger. Therefore, during explosions, shots and other rapid sounds, he does not have time to compensate for the noise.

Diseases of the middle ear

The structure of the middle ear is such that in case of its diseases, the normal conduction of sound first of all suffers and the threshold of auditory sensitivity sharply decreases. The causes of the disease of the inner ear are most often trauma, hypothermia or exposure to pathogenic microorganisms.

Moreover, viruses and bacteria can enter the ear not only through the external auditory canal, but also from the mouth or nose through the Eustachian tube. That is why SARS, influenza, rubella, tonsillitis are often complicated by otitis media.

Among the most common diseases of the middle ear, doctors note:

• acute and chronic otitis;
• barotrauma;
• mechanical injury;
• congenital pathologies;
• hearing loss 1-4 degrees.

Especially dangerous is purulent otitis media, which, if not properly treated, can lead to inflammation of the meninges (meningitis) and even general blood poisoning (sepsis). Pus accumulates behind the eardrum and presses on it, causing severe pain. Sometimes it is partially perforated, and in some cases - a complete rupture, which can lead to partial or complete hearing loss.

Unfortunately, the structure of the middle ear is such that diseases appear already at the stage when the inflammatory process has developed. The main symptoms of the disease of this organ are: sharp shooting pain, fever, often reddening of the tragus, headache, periodic dizziness.

With otitis media, pus or a yellowish exudate with an unpleasant odor may be released from the ear. If these symptoms appear, you should immediately consult a doctor. Procrastination and improper treatment threatens with very serious consequences.

The process of cognition and sound perception of the world is carried out with the help of the sense organs. Most of the information we receive through sight and hearing. How the human ear is arranged has long been known, but it is still not entirely clear how exactly the recognition of sounds that are different in height and strength occurs.

The auditory analyzer works from birth, although the structure of the infant ear is somewhat different. During a sufficiently loud sound, an unconditioned reflex appears in newborns, which is recognized by an increase in heart rate, increased breathing, and a temporary cessation of sucking.

By two months of life, a conditioned reflex is formed. After the third month of life, a person can already recognize sounds that are different in timbre and pitch. By the age of one, the child distinguishes words by rhythmic contour and intonation, and by the age of three, he is able to distinguish speech sounds.

What is an auditory analyzer

Vertebrates hear with the help of a paired organ - the ears, the inner part of which is located in the temporal bones of the skull. Two ears are needed not only to hear better, but also to help determine where the sound is coming from.

There are several explanations for this: the ear, which is closer to the source, picks up the sound stronger than the other; the near ear transmits information to the brain faster; sound vibrations are heard by the perceiving organ in different phases. What does the ear consist of and how does it provide sound perception and sound transmission?

Analyzers are complex mechanisms by which information is collected and processed. Analyzers consist of three links. The receptor section with the help of nerve endings perceives irritation. Conduction through nerve fibers transmits a sound impulse to the central nervous system.

The central section is located in the cortex, and here a specific sensation is formed. The structure of the human ear is complex, and if there is a violation of the function of at least one department, then the work of the entire analyzer stops.

The structure of the human ear

The device of the ear is the same in almost all mammals. The difference is only in the number of volutes of the cochlea and the limits of sensitivity. The human ear consists of 3 sections connected in series:

• outer ear;
• middle ear;
• inner ear.

An analogy can be drawn: the outer ear is a receiver that perceives sound, the middle part is an amplifier, and the inner ear of a person functions as a transmitter. The outer and middle ear are necessary for conducting a sound wave to the receptor section of the analyzer, and the human inner ear contains cells that perceive mechanical vibrations.

outer ear

The structure of the outer ear is represented by two areas:

• auricle (visible outer part);
• auditory canal.

The task of the auricle is to catch the sound and determine where it comes from. In animals (cats, dogs) the shell is movable, such an ear device facilitates sound perception. In humans, the muscle that causes the shell to move has atrophied.

The shell is a rather fragile formation, since it consists of cartilage. Anatomically, a lobe, a tragus and an antitragus, a curl and its legs, an antihelix are distinguished. The structure of the auricle, namely its folds, helps to find out where the sound is localized, as they distort the wave.

Individually shaped auricle

The external auditory canal is 2.5 cm long and 0.9 cm wide. The canal begins with cartilaginous tissue (which continues from the auricle) and ends. The channel is covered with skin, where the sweat glands have changed and began to secrete earwax.

It is needed to protect against infection and the accumulation of contaminants, such as dust. Normally, sulfur comes out when chewing.

The tympanic membrane separates the external canal and the middle ear. This is a membrane that does not let air or water into the body and is sensitive to the slightest fluctuations in air. Thus, it is necessary to protect the inside of the ear and transmit sound. In an adult, it is oval, and in a child it is round.

The sound wave reaches the eardrum and causes it to move. In order for a person to perceive different frequencies, a membrane movement equal in size to the diameter of a hydrogen atom is enough.

Middle ear

In the wall of the human middle ear, there are two openings closed by a membrane that lead to the inner ear. They are called oval and round windows. The oval window fluctuates due to the impact of the auditory ossicle, the round one is necessary for the return of vibration in a closed space.

The tympanic cavity is only about 1 cm3. This is enough to accommodate the auditory ossicles - the hammer, anvil and stirrup. The sound sets the eardrum in motion, which causes the hammer to move, which moves the stirrup through the anvil.

The function of the middle ear is not limited to the transmission of vibrations from the external to the internal canal; when the auditory ossicles move, the sound is amplified 20 times due to the contact of the base of the stapes with the membrane of the oval window.

The structure of the middle ear also requires the presence of muscles that will control the auditory ossicles. These muscles are the smallest in the human body, but they are able to ensure the adaptation of the body to the simultaneous perception of sounds of different frequencies.

From the middle ear there is an exit to the nasopharynx through the Eustachian tube. It is about 3.5 cm long and 2 mm wide. Its upper part is in the tympanic cavity, the lower part (pharyngeal mouth) is near the hard palate. The pipe is necessary to provide equal pressure on both sides of the membrane, which is necessary for its integrity. The walls of the tube are closed and expand with the movement of the pharyngeal muscles.

At different pressures, stuffiness of the ears appears, as if being under water, while yawning reflexively occurs. It will help to equalize the pressure of swallowing or a strong exhalation through the nose with pinched nostrils.

The eardrum can be broken due to pressure drop

The anatomy of the middle ear in childhood is somewhat different. In children, there is a gap in the middle ear through which the infection easily penetrates into the brain, provoking inflammation of the membranes. With age, this gap closes. In children, the auditory requirement is wider and shorter, located horizontally, so they often develop complications of pathologies of the ENT organs.

For example, with inflammation of the throat, bacteria travel through the auditory tube to the middle ear and provoke otitis media. Often the disease becomes chronic.

inner ear

The structure of the inner ear is extremely complex. This anatomical region is localized in the temporal bone. It consists of two complex structures called labyrinths: bony and membranous. The second labyrinth is smaller and located inside the first. Between them is the perilymph. Inside the membranous labyrinth there is also a liquid - endolymph.

There is a vestibular apparatus in the labyrinth. Therefore, the anatomy of the inner ear allows not only the perception of sound, but also the control of balance. The cochlea is a spiral canal, consisting of 2.7 turns. The membrane is divided into 2 parts. This membranous septum contains more than 24,000 elastic fibers that are set in motion by a sound of a certain pitch.

On the wall of the cochlea, the fibers are unevenly distributed, which helps to better identify sounds. On the septum is the organ of Corti, which perceives sound from the fiber-strings with the help of hair cells. Here, mechanical vibrations are transformed into a nerve impulse.

How does sound perception work?

Sound waves reach the outer shell and are transmitted to the outer ear, where they cause the eardrum to move. These vibrations are amplified by the auditory ossicles and transmitted to the membrane of the middle window. In the inner ear, vibrations provoke the movement of the perilymph.

If the vibrations are strong enough, they reach the endolymph, and it, in turn, provokes irritation of the hair cells (receptors) of the organ of Corti. Sounds of different pitch move the fluid in different directions, which is picked up by the nerve cells. They turn mechanical vibration into a nerve impulse that reaches the temporal lobe of the cortex through the auditory nerve.

The sound wave entering the ear is converted into a nerve impulse.

The physiology of sound perception is difficult to study because sound causes little membrane displacement, fluid vibrations are very small, and the anatomical region itself is small and encapsulated in the labyrinth.

The anatomy of the human ear allows you to capture waves from 16 to 20 thousand vibrations per second. This is not so much compared to other animals. For example, a cat perceives ultrasound and is able to catch up to 70 thousand vibrations per second. As people age, sound perception deteriorates.

So, a thirty-five-year-old person can perceive sound no higher than 14,000 Hz, and over 60 years old can pick up only up to 1,000 vibrations per second.

Ear diseases

The pathological process that occurs in the ears can be inflammatory, non-inflammatory, traumatic or fungal. Non-inflammatory diseases include otosclerosis, vestibular neuritis, Meniere's disease.

Otosclerosis develops as a result of pathological tissue growth, due to which the auditory ossicles lose their mobility and deafness occurs. Most often, the disease begins during puberty and a person by the age of 30 has severe symptoms.

Meniere's disease develops due to the accumulation of fluid in a person's inner ear. Signs of pathology: nausea, vomiting, tinnitus, dizziness, difficulty with coordination. Vestibular neuritis may develop.

This pathology, if it occurs in isolation, does not cause hearing impairment, however, it can provoke nausea, dizziness, vomiting, tremor, headache, convulsions. Most often noted.

Depending on the location of the inflammation, there are:

• otitis externa;
• otitis media;
• otitis media;
• labyrinthitis.

Occur as a result of infection.

If otitis media is ignored, the auditory nerve is affected, which can lead to permanent deafness.

Hearing is reduced as a result of the formation of plugs in the outer ear. Normally, sulfur is excreted on its own, but, in the case of increased production or a change in viscosity, it can accumulate and block the movement of the eardrum.

Traumatic diseases include damage to the auricle with bruises, the presence of foreign bodies in the auditory canal, deformation of the eardrum, burns, acoustic injuries, vibration injuries.

There are many reasons why hearing loss can occur. It can occur as a result of a violation of sound perception or sound transmission. In most cases, medicine can restore hearing. Medical therapy, physiotherapy, surgical treatment are carried out.

Doctors are able to replace the auditory ossicles or eardrum with synthetic ones, install an electrode in the human inner ear, which will transmit vibrations to the brain. But if hair cells suffer as a result of pathology, then hearing cannot be restored.

The device of the human ear is complex and the appearance of a negative factor can impair hearing or lead to complete deafness. Therefore, a person must observe hearing hygiene and prevent the development of infectious diseases.

When making this or that diagnosis, otolaryngologists, first of all, have to find out in which part of the ear the focus of the disease has arisen. Often patients, complaining of pain, cannot determine exactly where the inflammation occurs. And all because they know little about the anatomy of the ear - a rather complex hearing organ, consisting of three parts.

Below you can find a diagram of the structure of the human ear and learn about the features of each of its components.

There are many diseases that cause ear pain. To understand them, you need to know the anatomy of the structure of the ear. It includes three parts: outer, middle and inner ear. The outer ear consists of the auricle, the external auditory meatus and the tympanic membrane, which is the boundary between the outer and middle ear. The middle ear is located in the temporal. It includes the tympanic cavity, the auditory (Eustachian) tube and the mastoid process. The inner ear is a labyrinth consisting of the semicircular canals, responsible for the sense of balance, and the cochlea, which is responsible for converting sound vibrations into an impulse recognized by the cerebral cortex.

The photo above shows a diagram of the structure of the human ear: inner, middle and outer.

Anatomy and structure of the outer ear

Let's start with the anatomy of the outer ear: it is supplied with blood through the branches of the external carotid artery. In innervation, in addition to the branches of the trigeminal nerve, the ear branch of the vagus nerve, which branches in the posterior wall of the auditory canal, takes part. Mechanical irritation of this wall often contributes to the appearance of the so-called reflex cough.

The structure of the outer ear is such that the outflow of lymph from the walls of the ear canal enters the nearest lymph nodes located in front of the auricle, on the mastoid process itself and under the lower wall of the ear canal. Inflammatory processes that occur in the external auditory canal are often accompanied by a significant increase and the appearance of pain in the data area.

If you look at the eardrum from the side of the ear canal, you can see a funnel-shaped concavity in its center. The deepest place of this concavity in the structure of the human ear is called the navel. Starting from it anteriorly and upwards, there is a handle of the malleus, fused with a fibrous-like layer of the tympanic membrane. At the top, this handle ends with a small, pinhead-sized elevation, which is a short process. Anterior and posterior folds diverge from it anteriorly and posteriorly. They separate the relaxed part of the eardrum from the stretched one.

The structure and anatomy of the human middle ear

The anatomy of the middle ear includes the tympanic cavity, mastoid process, and Eustachian tube, which are all connected. The tympanic cavity is a small space located inside the temporal bone, between the inner ear and the tympanic membrane. The structure of the middle ear has the following feature: in front, the tympanic cavity communicates with the cavity of the nasopharynx through the Eustachian tube, and behind - through the entrance to the cave with the cave itself, as well as the cells of the mastoid process. Air enters the tympanic cavity through the Eustachian tube.

The anatomy of the structure of the human ear of the first up to the age of three differs from the anatomy of the ear of an adult: in newborns, there is no bony auditory meatus, as well as the mastoid process. They have only one bone ring, along the inner edge of which there is a so-called bone groove. The tympanic membrane is inserted into it. In the upper sections, where the bony ring is absent, the tympanic membrane is attached directly to the lower edge of the scale of the temporal bone, which is called the rivinium notch. When a child is three years old, his external auditory meatus is fully formed.

Diagram of the structure and anatomy of the human inner ear

The structure of the inner ear includes the bony and membranous labyrinths. The bone labyrinth surrounds the membranous labyrinth on all sides, having the appearance of a case. In the membranous labyrinth is the endolymph, and the free space remaining between the membranous and bony labyrinth is filled with perilymph, or cerebrospinal fluid.

The bony labyrinth includes the vestibule, cochlea, and three semicircular canals. The vestibule is the central part of the bony labyrinth. On its outer wall there is an oval window, and on the inner wall there are two depressions necessary for the sacs of the vestibule, which look like membranes. The anterior sac communicates with the membranous cochlea, located anterior to the vestibule, and the posterior sac communicates with the membranous semicircular canals located posteriorly and upward from the vestibule itself. The anatomy of the inner ear is such that otolith apparatuses, or terminal apparatuses of statokinetic reception, are located in the vestibule sacs that communicate with each other. They consist of a specific nerve epithelium, which is covered from above by a membrane. It contains otoliths, which are crystals of phosphate and carbonate of lime.

The semicircular canals are located in three mutually perpendicular planes. The external channel is horizontal, the posterior one is sagittal, the upper one is frontal. Each of the semicircular canals has one dilated and one simple or smooth pedicle. The sagittal and frontal canals have one common smooth pedicle.

In the ampulla of each of the membranous canals is a scallop. It is a receptor and is a terminal nervous apparatus, composed of a highly differentiated nerve epithelium. The free surface of the epithelial cells is covered with hairs that perceive any displacement or pressure of the endolymph.

The receptors of the vestibule and semicircular canals are represented by the peripheral endings of the nerve fibers of the vestibular analyzer.

The cochlea is a bony canal that forms two whorls around a bony shaft. The external resemblance to the common garden snail gave the name to this organ.

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