Body support and movement. What supports the body of colonial coral polyps
The skeleton serves as a support for the body, and this is its main significance. The human skeleton consists of more than two hundred bones. Some of them, for example, the frontal, two parietal, occipital to other bones of the skull, are connected to each other immovably and very firmly, because they have numerous protrusions of one bone that enter the corresponding recesses of the other. This is how the boards are connected with spikes. Bone spikes are very diverse and bizarre. In ancient times, in India, they were taken for mysterious signs and they thought that their fate was written on the skull of a person with these signs.
The skeleton is not only the support of the body. It also protects some organs from shock and damage. Yes, the brain is well protected. cranium; spinal cord located in the spinal canal, which is formed from individual bone rings-vertebrae; lungs, heart, liver, spleen are covered with ribs, which are connected behind the spine, and in front with the sternum.
SUPPORT IS MOVABLE
If all the bones were connected to each other motionlessly, a person would be like a stone statue: he could not make any movement. But many bones are not fixedly connected, and this makes it possible for a person to move and take various positions. These movable joints of bones are called joints. In the joint, the areas of adjacent bones that are in contact with each other are covered with smooth, slippery cartilage and are, as it were, ground to each other. If the surface of one bone is convex, then the surface of the other has a corresponding depression.
The movements of the bones in different joints are not the same. For example, the leg at the knee only bends and unbends, while other movements are almost impossible for it. We not only bend and unbend the fingers of the hand, but also move them to the side. In some joints, the bone can also rotate.
Features of movements in each joint depend on the shape articular surfaces bones. The most diverse movements of the bones are where the surface of the joints spherical shape, for example, in shoulder joint.
In each joint, around the adjoining parts of one and the other bone, there is a dense, impermeable even for air shell. Its edges are fused with adjacent parts of the bones. This shell is called the articular bag. Its strength is increased by special ligaments fused with bones.
It is known from physics that if two hollow hemispheres are attached to each other, the edges of which are in close contact at all their points, and air is pumped out of them, then to separate them, you need to apply a huge force that would overcome the pressure of atmospheric air on outer surface hemispheres.
The same can be said about the joints. There is no air inside the joints. It is very difficult to stretch the joint, i.e., push the bones in contact, because this will be prevented Atmosphere pressure outside air, which presses the bones together. It has been established that the strength of a joint decreases sharply if it is pierced with a pin. It is very easy to make movements in the joint. You can raise your hand, stretch it forward or take it to the side. With each such movement, the bones continue to touch each other, but their relative position changes.
It would seem that the mobile joints of the bones should interfere with the supporting function of the skeleton. In fact, try replacing ordinary table legs with ones that, like human legs, would consist of several movably connected links. It is unlikely that anyone will agree to dine or work at such a table. However, in reality, the mobile connection of most of the bones of the skeleton not only does not violate its supporting function, but, on the contrary, makes it more perfect.
AND YET THE SUPPORT IS STABLE
The skeleton serves as a support for the whole body and its individual parts under any conditions: when a person lies or stands, and when he walks or works. This is due to the fact that each joint can be temporarily fixed in one position or another and become immobile. When a person is standing, his knee joint is firmly fixed in an extended position. It is worth squatting down, as the same joint will be fixed in a bent position.
Temporary fixation of the joint, as well as a change in its position, is carried out by skeletal muscles. Almost all muscles are connected at their ends to two bones, most often neighboring ones.
A nerve comes to each muscle from the spinal cord and brain. Waves of excitement rush through it one after another. Reaching the muscle, they make it work. And the work of the muscle is that it is reduced, in other words, it is shortened. When contracting, the muscles pull the bones along with them, and this leads to the movement of the body or its individual parts. Consequently, during movements, the muscles play an active role, and the bones - a passive one; they continue to perform their main function, namely to serve as a support for each part of the body. The bones, together with the muscles attached to them, are usually called the organs of movement, or, more correctly, the musculoskeletal system.
LEVERAGE OF OUR BODY
What happens to the bones to which the ends of the contracting muscle are attached?
Suppose a person bends his arm at the elbow while stationary humerus. Then the forearm, together with the hand, can be considered as a lever, which is set in motion by the shoulder muscle and the biceps, or biceps: the elbow joint is the fulcrum; the center of gravity of the forearm and hand is the point of application of the force that pulls the lever down; the place of attachment of both muscles is the point of application of the force that raises the lever.
This is a lever of the second kind. In it, the points of application of the acting and opposing forces are on the same side of the fulcrum. We often use such leverage in life. Such, for example, are nutcrackers or waga - a pole that is used to move or turn a thick log, a large stone or other heavy object. In levers of the second kind, the point of application of the acting force is usually located at a greater distance from the fulcrum than the point of application of the opposing force. This makes it possible to overcome a very significant opposition with relatively little effort.
Let's try to figure out what's going on here. Let's take a lever of the second kind 50 cm long. To its middle we will attach two cords with identical weights weighing 20 g each. One cord is thrown over the block and pulls the lever up, and the other pulls it down. The weights precisely balance each other, and the lever does not rise or fall.
Now let's move the attachment points of the cords. We will strengthen the cord thrown over the block at the very end of the lever, and leave the other cord in the old place. In this case, the first cord, which pulls the lever up, will be attached to the lever at a distance twice as large from the fulcrum as the second cord. Will the balance be maintained? Of course not: the lever will immediately rise. To restore balance, you must either halve the load of the far cord, or double the load of the near cord.
Let's do a more complicated experiment. We move the cord that pulls the lever down to the fulcrum so that it is at a distance of 5 cm from it. The weight of the load is still 20 g. We will gradually move the other cord along the lever. First, we will strengthen it at a distance of 10 cm from the fulcrum. Then, to balance on this cord, it is necessary to hang not 20, but only 10 G. Let's move the cord even further so that it is 25 cm from the fulcrum. Now 4 G is enough to achieve equilibrium.
The farther away from the fulcrum is the place of attachment of the cord pulling the lever up, the less weight can balance the lever. If this cord is attached at a distance of 50 cm from the fulcrum, that is, at the very end of the lever, then 2 G is enough to balance a load of 20 G attached to the lever at a distance of 5 cm from the fulcrum.
It is easy to see that the force required to move the lever must be less than more distance from the place of application to the fulcrum. Putting a nut in the recess of the tongs, which is very close to the fulcrum of the lever, we easily split it. The effort required for this is significant. less than that, which is necessary to crack the nut by pressing on it without using a lever.
In the levers of our body, the points of application of force and reaction are almost always located differently: closer to the fulcrum is the place of attachment of the muscle, i.e., the acting force. Therefore, in order to overcome the resistance, the muscles must develop a very great power. However, this results in a significant gain in the range of motion.
Suppose a person is holding an object weighing 1 kg in a bent hand. The point of opposition, i.e., the center of gravity of the forearm, together with the loaded hand, is 8-10 times farther from the fulcrum than the point of application of force, i.e., the place of attachment of the muscle. Therefore, in order to hold a load weighing only 1 kg, the muscle must contract with the force necessary to lift a load of about 10 kg.
JOINTS ARE PARTIALLY SECURED EVEN WHEN MOVING
When a person is standing support function the skeleton can be carried out only if each movable connection of the bones of the legs, torso, neck and head is motionless fixed in a certain position. The work of strengthening the mobile joints of the bones is performed by our muscles. Their coordinated work ensures that the balance is maintained. The force of contraction of individual muscles is constantly changing in full accordance with the forces created in each this moment conditions for maintaining equilibrium. If the bones were fixed to each other, the skeleton could not perform its supporting function with such perfection.
Of particular interest is the supporting function of the skeleton during movement. When it is necessary to stretch the arm forward, the shoulder joint should be fixed so that movement in the desired direction is easy, but that it is impossible to rotate the arm and move it to the side. In other words, there is a partial fixation of the joint, allowing only one specific movement.
During work, the direction of movement in the joints is constantly changing, which means that at any given moment, the partial fixation of the joints occurs in different ways.
THE MOST PERFECT LUBRICANT
The stronger two objects rub against each other, the more their rubbing surfaces heat up. The heat generated can ignite and ignite flammable objects. Already primitive people they knew how to make fire by friction. And until now, we usually use friction to make fire: we strike a match on a box.
However, much more often we have to think not about how to use friction, but about how to deal with it. Friction is a hindrance to movement. The point is not only that the rubbing surfaces in the machines are heated. Friction delays, slows down movement. The rubbing parts are usually gradually erased, destroyed, and therefore from time to time the machine needs to be repaired.
With every movement, the articular surfaces of the bones rub against each other. To reduce and prevent the harmful effects of friction, lubrication is essential. And in fact, every joint has a lubricant, it is released on the inner surface of the articular capsule. In addition, the rubbing cartilage pads themselves form the lubricant.
Cartilage is not dead matter. That part of it, which fuses with the bone, grows all the time, replacing the rubbing, collapsing surface of the cartilage. The more movements are made in the joint, the more the surfaces of its cartilaginous layers are erased, the faster the cartilage grows. In this way, there is a kind of constant current repair of the rubbing parts of our body.
When destroyed, the surface layer of cartilage pads turns into a lubricant for the joint. Friction surfaces lubricate themselves, constantly maintaining a uniform thin layer of lubricant. This is why the articular surfaces of bones are always wet and slippery.
There is not a single machine in the world in which, like a human joint, the rubbing surface, partially destroyed, would turn into a lubricant, and at the same time restore itself.
Each machine must be cleaned from time to time, it is necessary to remove used lubricants. And the human joint does not need to be cleaned. The spent lubricant is absorbed into the blood through the wall of the joint capsule, just as nutrients necessary for the body are absorbed into the blood in the intestinal wall. As a result, excess and unusable lubrication is constantly removed from the joint.
The joints take care of themselves. And this self-service is so perfect that during the whole human life they can work flawlessly. Only in certain diseases articular rheumatism, gout - the normal functioning of the joints is disturbed, and then the movements become difficult and painful.
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90. Consider a drawing depicting a human skeleton. Label the bones.
91. Complete the sentence.
The human musculoskeletal system consists of the bones of the skeleton, their joints and muscles.
92. Answer in writing the question: what is the meaning of the skeleton?
It serves as a support for the body and its organs. The bones of the trunk and limbs are the levers with which the body moves in space. The skeleton also creates the structural shape of the body, determines its dimensions. Parts of the skeleton - such as the skull, chest, pelvis - form receptacles for vital important organs(brain, heart, lungs, stomach, genitals and other organs). Performs a skeleton and other functions, for example, participates in metabolism.
93. Perform practical work « External structure bones."
1. Review the bone specimens or dummies given to you by your teacher.
2. Determine which group of bones (tubular, flat or mixed) these objects belong to. Justify your answer.
3. Draw in a notebook and sign the studied objects.
4. In the absence of specimens or models of bones, use the drawing to complete this work. Determine which groups the bones shown in the figure belong to, and sign them.
94. Complete the sentences.
1. Flexibility and elasticity give the bones organic matter.
2. Hardness is given to the bones by minerals.
95. Why do bones become more fragile in older people, fractures occur more often?
Because with age, organic matter becomes less, therefore, in older people, the bones are more fragile and brittle.
96. Study the section "Structure of the bone" in the textbook. Consider the drawing. Write the names of the structures indicated by numbers.
97. How is bone growth in length and thickness carried out?
The growth of bones in thickness occurs due to cell division of the inner layer of the periosteum. In length, young bones grow due to the cartilage located between the body of the bone and its ends.
98. Look at the picture. Sign the types of bone connections shown in the figure, indicated by numbers.
99. Look at the picture. Write the names of the parts of the joint indicated by numbers.
100. Look at the pictures. Write the names of the bones of the skull. Color the bones of the facial section with a colored pencil.
101. List the sections of the spine and indicate the number of calls in each section.
102. Look at the pictures. Write the names of the bones of the upper and lower limbs, indicated by numbers.
Upper limb bones
1. Clavicle; 2. Shoulder; 3. Humerus; 4. Elbow bone; 5. Radius; 6. Metacarpal bones; 7. Bones of the wrist; 8. Phalanges of fingers.
Bones lower limb
1. Pelvic bone; 2. Femur; 3. Tibia; 4. Tibia; 5. Tarsal bones; 6. Metatarsal bones; 7. Phalanges of fingers.
103. Consider a natural vertebra. Sketch it and label the main parts.
104. Underline the names of the bones that make up the chest.
Ribs, cervical vertebrae, sternum, sacrum, thoracic vertebrae, collarbones.
Current page: 7 (the book has a total of 19 pages) [accessible reading excerpt: 13 pages]
Support and movement
Skeleton bones
It is hard to imagine what a person would look like without a musculoskeletal system. Most likely, it would resemble a jellyfish pulled ashore. He would not be able to actively move, and any, even a minor injury, would damage internal organs caused a concussion.
Musculoskeletal system a person is made up of the bones of the skeleton, their joints and muscles.
SIGNIFICANCE OF THE SKELETON. Let's look at the human skeleton (from the Greek "skeleton" - dried up, dried up). It serves as a support for the body and its organs. The bones of the trunk and limbs are the levers with which the body moves in space. The skeleton also creates the structural shape of the body, determines its dimensions. Parts of the skeleton, such as the skull, chest, pelvis, form receptacles for vital organs (brain, heart, lungs, genitals and other organs). Performs a skeleton and other functions, for example, participates in metabolism.
The skeleton is made up of over 200 interconnected bones.
FORM OF BONES. The bones of an adult make up about 18% of his body weight. They differ in form and function.
Human skeleton
Distinguish tubular bones, they can be long (eg, humerus, femur) or short (carpus, metatarsus, phalanges). These bones consist of an elongated middle part (body, or diaphysis) and two thickened ends (heads, or epiphyses). There is a cavity inside the body of the bone. spongy bones located where a combination of strength and mobility is needed (carpal bones, tarsus). wide, or flat, bones participate in the formation of the walls of cavities containing internal organs (bones of the cerebral part of the skull, pelvic bones). Their width and length significantly predominate over their thickness. mixed dice have a complex shape and consist of several parts that have different structure and outlines. These are the vertebrae, the bones of the base of the skull.
The structure of the bone
Compact (dense) matter
red bone marrow
spongy substance
BONE STRUCTURE. The skeleton as a support carries a large load: an average of 60–70 kg (this is the body weight of an adult). Therefore, the bones must be strong.
Bone has a complex chemical composition, it consists of organic and inorganic substances. The bulk of dry bone is inorganic substances(65–70%). These are mainly salts of phosphorus and calcium. Bone cells are composed of organic matter (30–35% dry bone mass). Elasticity and resilience of the bone depend on organic substances, and hardness depends on mineral substances. The combination of these substances provides high strength to living bones. In terms of hardness, it can be compared with cast iron, bronze.
IN young age and in children, the bones are more elastic and resilient, since organic substances predominate in them. With age, organic matter becomes less, so in older people, the bones are more fragile and brittle.
Each bone consists of several types of tissues, the main among them is bone. This special type connective tissue. Bone made up of bone cells intercellular substance and has a lamellar structure in humans.
Each bone has a compact (dense) and spongy substance. Their quantitative ratio and distribution depends on the place of the bone in the skeleton and on its function.
Particularly well developed compact matter in those bones and their parts that perform the functions of support and movement. For example, the body of long tubular bones is built from a compact substance.
In a dense substance, bone plates form complex cylindrical structures, as if inserted into one another. Such tubular structure compact bone substance provides the bones with greater strength and lightness. Through special channels, the blood vessels that feed them penetrate into the bones.
spongy substance formed by many bone plates, which are located in the directions of the greatest load. In flat and spongy bones, as well as in the terminal thickenings (epiphyses) of long tubular bones, red bone marrow is located between the plates. It produces blood cells. The cavities of long tubular bones in adults are filled with yellow bone marrow containing fat cells.
Outside, each bone (except articular surfaces) is covered periosteum. This is a thin connective tissue sheath that is firmly fused to the bone. It is rich in nerves and vessels that penetrate deep into the bone through branching canals.
BONE GROWTH. As a person grows, his bones grow in length and thickness. The growth of bones in thickness occurs due to cell division of the inner layer of the periosteum. In length, young bones grow due to cartilage located between the body of the bone and its ends. The development of the skeleton in men ends by the age of 20-25, in women - at 18-21 years.
BONE JOINTS. Individual bones of the human skeleton are interconnected.
The way the bones are connected depends on their function. There are continuous (fixed and semi-movable) and discontinuous (movable) joints of bones.
Continuous connections are present between the bones of the skull, pelvis (fixed). Between the connecting bones is a thin layer of connective tissue or cartilage. The joints between the bones of the roof and the facial part of the skull are called seams. Serrated sutures are distinguished when the serrated edge of one bone of the skull roof is connected to a similar edge of another bone.
Continuous (semi-movable) connections are between the bodies of the vertebrae of the spinal column, between the tibia bones of the lower leg. A slight mobility of these joints is achieved with the help of cartilaginous plates and elastic ligaments.
Intermittent connections with a gap between the connecting bones is called joints. The joints allow a person to produce various movements.
The joint is formed by the ends of connecting bones, enclosed in joint bag. The ends of the bones are covered with smooth elastic cartilage, the presence of which facilitates the movement of the joint. The secreted inner surface joint bag special joint fluid, which acts as a lubricant. The shape of the connecting bones allows you to perform certain types movements. So, in the shoulder joint, the head of the humerus has the shape of a ball, and the corresponding surface at the scapula forms a fossa. Outside the bag, and sometimes inside the joint is strengthened bundles. Movement in the joints is carried out by muscles.
The structure of the knee joint
Types of joints
cartilage tissue
Types of bone connection
Our bones are capable of withstanding enormous stresses. For example, femur a long jumper at the moment of landing experiences a load of 9 tons! But you can break everything, including absolutely healthy bones. Experiments have shown that bones break under tension up to 3600 kg/cm 2 and break under compression at 5400 kg/cm 2 .
Almost any sport can lead to injury. Most of of these injuries is associated with damage to the joints. Most often, knee joints are affected - 25% of injuries, elbow joints - 13, shoulders - 10, pelvis - 9, ankles and feet - 5, wrists - 4%. Very frequent injury is a meniscus tear. The menisci are two crescent-shaped cartilages located at the knee joint between the ends of the femur and tibia. With awkward movements, these cartilages can be destroyed. Sometimes they wear out a lot during many years of sports loads and tear even with the most ordinary movements.
Located between tendons and bones synovial bursa- soft padding that reduces friction. With constant stress on the joint, edema occurs synovial bag, accompanied by severe pain. This disease is called bursitis. For example, often occurring bursitis of the elbow joint in tennis players is called “tennis elbow”. Of course, injuries to the elbow joint can also occur in athletes involved in other sports. And tennis is far from the most traumatic activity. Very often the joints are damaged in skiers.
Dislocation of the interphalangeal joint
Fracture of the tibia
Test your knowledge
1. What does the musculoskeletal system consist of?
2. What functions does the skeleton perform?
3. What is the chemical composition of bones?
4. What tissue forms the bone?
5. What are the bones in shape? Give specific examples.
6. How are the structural features of spongy and compact matter related to their functions?
7. The tibia with a small mass (about 0.5 kg) can withstand loads up to 1500 kg. What makes this possible?
8. Summarize what determines the lightness of the bones; bone strength.
9. Compare the structure, location and significance of red and yellow bone marrow.
10. How do bones grow in length and thickness?
11. What are the joints of bones?
12. What is the structure of the joint?
13. It is known that in children the bones are more elastic and resilient than in adults. What is the reason and significance of this feature?
Complete work No. 4 “Investigation of the properties of normal, burnt and decalcified bone” and No. 5 “Study of appearance individual bones"(Notebook for laboratory and practical work).
Work with computer
http://school-collection.edu.ru/catalog (Human Anatomical and Physiological Atlas / Musculoskeletal System / Skeleton)
The musculoskeletal system consists of the skeleton and muscles. The skeleton is made up of bones, cartilage, ligaments, and joints. He performs the support and protective function. Chemical composition, structural features of bones provide their strength and lightness. There are tubular, flat, mixed bones. Bone connections can be continuous or discontinuous. The growth of bones in thickness is carried out due to the division of periosteal cells, in length - due to cartilage cells between the body and the ends of the bone.
Skeleton structure
In the human skeleton, there are: the skeleton of the head, the skeleton of the body and the skeleton of the upper and lower extremities.
SKELETON HEAD (SKULL). The skull consists mainly of flat, motionless bones connected to each other. The only movable bone of the skull is the lower jaw. The skull protects the brain and sense organs from external damage, provides support for the muscles of the face and primary departments digestive and respiratory systems.
In the skull, a large brain and a smaller facial section are distinguished. brain department skulls form following bones: unpaired - frontal, occipital, wedge-shaped, ethmoid and paired - parietal and temporal.
The structure of the skull
The structure of the chest
The largest bones facial department- paired zygomatic, maxillary, as well as nasal and lacrimal bones, unpaired - the lower jaw and the hyoid bone located on the neck.
BODY SKELETON. The skeleton of the body consists of the spine and chest. Spine connects parts of the body, performs a protective function for the spinal cord and a support for the head, arms, torso. Upper section spine supports the head. The length of the spine is about 40% of the length of the human body.
The spine consists of 33-34 vertebrae. It distinguishes following departments: cervical(7 vertebrae), chest (12), lumbar (5), sacral(5) and coccygeal(4–5 vertebrae). In an adult, the sacral and coccygeal vertebrae fuse into the sacrum and coccyx.
Spinal cord in the spinal canal
Departments of the spine
The human spine has bends that play the role of a shock absorber: thanks to them, shocks are softened when walking, running, jumping, which is very important for protecting internal organs and especially the brain from concussions.
The spine is made up of vertebrae. Typical vertebra consists of a body from which an arc departs from behind. Processes depart from the arc. Between the posterior surface of the vertebral body and the arch is the vertebral foramen.
Superimposed on each other, the vertebral foramens form spinal canal, which contains the spinal cord.
Rib cage formed by 12 pairs of ribs, movably connected to thoracic region spine and sternum. The chest protects the heart, lungs, large vessels and other organs from damage, serves as an attachment site for the respiratory muscles and some muscles upper limbs.
SKELETON OF LIMB. In humans, unlike most other animals, the functions of the limbs - arms and legs - are clearly delineated. The structure of the hand provides a variety of complex movements, the legs serve for support and movement.
Skeleton of the upper limb
hand skeleton
The skeleton of any limb consists of two parts: limb belts And free limb skeleton. The bones of the limb girdle connect the free limbs to the skeleton of the body.
The upper limb belt is formed by two shoulder blades and two collarbones. The skeleton of the free upper limb consists of three sections: humerus, bones forearms And brushes. The humerus forms a movable joint with the scapula ( shoulder joint), allowing you to make various movements with your hand.
Forearm formed ray And ulnar bones. The ability of the radius to rotate around the ulna allows you to perform such movements as turning a key, turning a screwdriver.
Brush formed big amount small bones. It has three departments: wrist, metacarpus And phalanges of fingers.
Belt of the lower extremities ( pelvic girdle) make up two pelvic bones, which connect with sacrum. The pelvic bones together with the sacrum form a ring on which the spinal column(torso). The skeleton of the lower extremities and muscles are connected to the pelvic bones, it serves as a support for them and takes part in their movements. The pelvic girdle also supports and protects the internal organs.
Skeleton of the lower limb
Foot skeleton
The skeleton of the free lower limb consists of femur, bones shins And feet. The massive femur is the largest bone in the human skeleton.
The bones of the leg are tibial And small tibia.
The bones of the foot are divided into bones tarsus, metatarsus And phalanges of fingers.
The human skeleton makes up about 15% of the human body weight. On average, it weighs about 17 kg. Oddly enough, it is not possible to accurately indicate the number of bones in the human skeleton. Various authors count from 206 to 230 bones in its composition. These discrepancies are due to the fact that people do not have the same number of vertebrae, ribs and other bones. The number of bones in the skeleton also changes with age. The longest bone in the skeleton is femoral- its length averages 27.5% of a person's height; the smallest bone is one of the auditory bones of the middle ear ( stapes). In men with a height of 180 cm, the length of the femur is 50 cm. Although there are people with a much longer femur. As for the stirrup, in all people its length is about 2 mm.
Most A tall man, whose growth is documented, is Robert Wadlow from the USA. His height was 272 cm. The smallest person on Earth was Polina Master from the Netherlands. Her height was 59 cm.
Human growth experiences daily fluctuations. During the day, growth decreases by an average of 2 cm, and with heavy loads - by 5 cm! This is due to the compression of the cartilaginous layers between the vertebrae. During a night's sleep, growth is restored.
body proportions
Who among us has not admired the sculptures Ancient Greece, wonderful paintings of the Renaissance! What attracts us, people of the 21st century, to amazing creations, whose age sometimes exceeds 2-5 thousand years? Undoubtedly the beauty human body.
The doctrine of body proportions arose during the heyday of the Egyptian state. The Egyptians found that the length of the human body is 19 times more length middle finger. They observed this rule when creating statues. Ancient Greek sculptors used the width of the palm as a unit of measurement; they expressed the proportions of the body as follows: two palm widths - the height of the face, three - the length of the foot, four - the distance from the shoulder to the elbow, etc.
With the development of science and art, anatomists and artists established a number of similar relationships, for example: three head lengths are equal to the length of the body, three lengths of the hand are the length of the arm, three lengths of the foot are the length of the legs, and the arm span is equal to the length of the body. Undoubtedly, the great Renaissance artist Leonardo da Vinci was well aware of this.
Facial proportions
The face of a person… Out of the billions of people living on Earth, you can’t meet two with the same faces: each nature creates according to an “individual project”. This is our "visiting card" in the vast world, on it is the seal of our originality, originality, our "I". Academician P. K. Anokhin wrote: “The beauty of the human face, its sparkling individuality, the various manifestations of its expressive play are a source of inspiration at all times and among all peoples.” Indeed, sculptors and painters, composers, writers and poets sang of the human face in marble and bronze, in colors and sounds, in poetry and prose. And if you have a work of an artist in front of you, then you see not just a portrait, but the innermost essence of a person, his inner world. This world inexplicably appears in all its features: in the depths of the eyes, in the corners of the lips, in the network of wrinkles ... Yes, it is no coincidence that the face is called the mirror of the soul.
Creating their masterpieces, artists and sculptors have long been interested in the size and proportions of the face. According to the ancient Greek sculptor Polykleitos, the face should be 1/10 of the length of the entire body. A face is considered proportional if it can be conditionally divided by lines horizontally into 4 equal parts: from the top of the head to the edge hairline, then the forehead area is highlighted, and the next line is drawn directly under the nose. It is also believed that, on average, the distance between the high boots should be equal to the distance from the eyebrow to the lower edge of the chin, and the distance between the outer corners of the eyes should correspond to that from the upper border of the nose to the upper border of the chin (the edge of the lower lip).
However, neither the exact proportions nor the strict symmetry of the right and left halves of the face yet guarantee its beauty. By the way, a slight asymmetry is inherent in the faces of all people without exception. Even the faces of Venus de Milo and Apollo Belvedere - universally recognized standards of beauty and harmony - do not have complete bilateral symmetry. What can we say about mere mortals! We have one half of the face, usually the left, higher, and the other lower. The high half is always a little narrower, the eyebrow is located a little higher on it, palpebral fissure larger and nasolabial fold more pronounced and direct.
The reason for the asymmetry of the face is the asymmetry of the bones that form the facial skeleton.
Test your knowledge
1. What are the main parts of the human skeleton?
2. What is the structure and meaning of the skull? Why are the bones of the skull connected motionless?
3. List the bones that form brain department skulls.
4. Name the only movable bone of the facial skull. What is its function?
5. Name the sections of the spine and the number of vertebrae in each of them. What role does the curvature of the spine play? In connection with what they appear in humans?
6. What departments does the limb skeleton consist of? What bones form the skeleton of the girdle of the upper limbs; lower limbs? draw general scheme structures of the human free limb.
7. Suggest how you can explain the similar structure of the upper and lower limbs in humans.
8. What is bone pelvis? Why does a person have it in the shape of a bowl?
9. Are there sex differences in the structure of the skeleton? If so, which ones?
Work with computer
Refer to the electronic application. Study the material of the lesson and complete the suggested tasks.
http://www.medicinform.net/human/anatomy/anatomy3_1.htm (The value of the musculoskeletal system. The structure and growth of bones. The human skeleton)
The human skeleton consists of a head skeleton, a torso skeleton, and a limb skeleton. In the skeleton of the head - the skull - there are cerebral and facial sections. The skeleton of the body is formed by the spine and chest. Five sections are distinguished in the spine, it has bends that soften shocks when running and walking. The chest contains the lungs, heart and other organs. It is formed by 12 pairs of ribs, the sternum and the thoracic spine. The limb skeleton consists of the limb girdle and the free limb skeleton.
Muscles. general review
Whatever a person does - walking, running, driving a car, digging the ground, writing - he performs all his actions with the help of skeletal muscles. These muscles are the active part of the musculoskeletal system. They hold the body in an upright position, allow you to take a variety of poses. The abdominal muscles support and protect the internal organs, that is, they perform supporting and protective functions. Muscles are part of the walls of the chest and abdominal cavities, the walls of the pharynx, provide movement of the eyeballs, auditory ossicles, respiratory and swallowing movements. This is only a partial list of skeletal muscle functions.
Therefore, it is not surprising that the mass skeletal muscles in an adult is 30-35% of body weight. A person has more than 600 skeletal muscles, they are formed by striated muscle tissue.
Muscle structure
STRUCTURE OF SKELETAL MUSCLES. Each muscle consists of parallel bundles of striated muscle fibers. Each bundle is dressed in a sheath. And the whole muscle is covered on the outside with a thin connective tissue sheath that protects the delicate muscle tissue.
Each muscle fiber is a multinucleated cylindrical cell. The diameter of these cells ranges from 5 to 100 microns, the length reaches 10–12 cm. Inside the fiber there are numerous thin contractile filaments - myofibrils. Myofibrils are made up of two types of contractile proteins. actinome And myosin. These proteins are arranged in myofibrils in an orderly manner, so that myosin molecules enter the gaps between actin molecules. Therefore, dark and light areas alternate in the myofibril. Hence the name of skeletal muscles - striated. At the moment when from nervous system comes to the muscle nerve fiber an electrical signal, the molecules of contractile proteins begin to interact with each other and the myosin filaments go deeper into the gaps between the actin molecules - the muscle contracts and thickens.
Muscle fibers
In higher animals and humans, skeletal muscles consist of two types of fibers: red and white. They differ in the composition and number of myofibrils, and most importantly, in the features of contraction. The so-called white muscle fibers contract quickly, but quickly get tired; red fibers contract more slowly, but can remain contracted for a long time. Depending on the function of the muscles, certain types of fibers predominate in them.
Muscles perform great job so they are rich blood vessels through which blood supplies them with oxygen, nutrients removes metabolic products.
Muscles are attached to bones by inextensible tendons, which fuse with the periosteum. Usually, the muscles are attached at one end above, and at the other below the joint. With this attachment, muscle contraction sets the bones in motion at the joints. The part of the muscle that can contract is called the abdomen.
MAIN GROUPS OF MUSCLES. Depending on the location of the muscles can be divided into the following large groups: muscles of the head and neck, muscles of the trunk and muscles of the limbs.
Muscles of the head According to their functions, they are divided into chewing and mimic. Chewing muscles located on the sides of the head, four on each side. Attached at one end to the skull and the other to mandible, when reduced, they set it in motion. Mimic muscles differ from all skeletal muscles in that they are attached to the bones of the skull at one end, and to the skin at the other. Therefore, when they are reduced, the shape and depth change. skin folds. Mimic muscles are mainly located around the openings - oral, eye, ear, nasal and anatomically independent of each other. Contracting, mimic muscles are able to reflect the mental state, mood of a person. In animals, facial muscles are much less developed than in humans.
Neck muscles keep the head in balance, participate in the movements of the head and neck, as well as in the processes of swallowing and pronouncing sounds.
Major muscle groups
Muscles of the head
TO torso muscles include muscles chest walls, abdomen and back. Let's look at the functions of some of them.
Intercostal muscles and diaphragm, changing the volume of the chest, play important role in breath. Large and small pectoral, anterior dentate, attached to both the ribs and the scapula, the humerus, participate in the movements of the hand and in breathing.
The abdominal muscles form walls abdominal cavity in which many internal organs are located. By contracting, these muscles are involved in flexion of the spine, in respiratory movements, and affect the functioning of internal organs. For example, they are involved in bowel movements, excretion of urine, and promote the movement of blood through the veins.
In the back area, the muscles are located in several layers. Most of them are involved in the movement of the spine back (extension) and to the sides. These are deep back muscles. The superficial muscles of the trunk (eg, trapezius, latissimus dorsi) are involved in the movements of the head, upper limbs, and chest.
Muscles of the trunk and limbs
Muscles of the limbs. The muscles of the girdle of the upper extremities move the arm in the shoulder joint. The most important of these is the deltoid muscle. With its contraction, the arm is retracted from the body to horizontal position. The biceps muscle flexes the arm in elbow joint, the triceps muscle of the shoulder - unbends. Muscles that flex, extend, and rotate the hips begin at pelvic bones, the other end is attached to the femur. For example, the iliopsoas muscle flexes the hip in hip joint, and the large gluteal - unbends. On the thigh is the longest (up to 50 cm) muscle of the human body - the tailor. The quadriceps femoris extends the lower leg at the knee joint, at the same time it is involved in hip flexion at the hip joint.
Test your knowledge
1. What is the active part of the musculoskeletal system?
2. Remember what types muscle tissue are found in the human body. Which of them is formed by the muscles of skeletal muscles?
3. How are muscles attached to bones?
4. Explain the mechanism of contraction of striated fibers. Why were they named like that? How is the regulation of the processes of contraction and relaxation of muscle fibers?
5. What is the difference between red and white muscle fibers?
6. How is the skeletal muscle structured? What structures, besides muscle fibers, does it contain?
7. What groups can skeletal muscles be divided into?
8. What are the features of attachment of mimic muscles?
9. Why are they on the shoulder large muscles, and on the forearm - a lot of small muscles?
10. Name the longest muscle in our body.
11. Describe the functions of the muscles indicated in the figure.
Laboratory and practical work
Complete work No. 9 “Measuring the mass and height of your body” (Notebook for laboratory and practical work).
Work with computer
Refer to the electronic application. Study the material of the lesson and complete the suggested tasks.
http://school-collection.edu.ru/catalog (Human Anatomical and Physiological Atlas / Musculoskeletal System / Muscular System)
The active part of the musculoskeletal system is skeletal muscles. They are attached to bones by tendons that fuse with the periosteum. There are muscles of the head and neck, trunk and limbs.
Skeleton is a construction of 212 bones. It serves as a support for the body and protects its sensitive organs: they are covered with bone membranes, put away in boxes of bones, in bone capsules and channels.
A skeleton is a structure made up of 212 bones. (There are 300 of them in a child's body. As he grows, some of the bones fuse together.) Skeleton creates support for the body and protects its sensitive organs: they are covered with bone membranes, put away in boxes of bones, hidden in bone capsules and channels. The basis of the skeleton is connective tissue, reinforced with calcium salts. This material is as hard as concrete. However, the skeleton is distinguished not only by strength, but also by amazing lightness. In an adult, its weight is less than 20% of body weight.
Figuratively speaking, the basis of the skeleton is a tower with 38 floors. It's called the spine. It consists of 7 cervical, 12 thoracic, 5 lumbar, 5 sacral and 4-5 coccygeal vertebrae. It appeared about 500 million years ago. Subsequently, whatever nature invented, it attached to the spine: the giant tail fin of a whale, the legs-columns of an elephant, the massive skull of a bison ... Nevertheless, the spine is flexible, like a steel spring. Maybe you saw a “snake woman” in the circus: amusing the audience, she arches her whole body back and touches her heels with the back of her head.
Inside the spine there is a through cavity - the spinal canal, lined with fibrous connective tissue - the dura mater. Here, in this cavity, the light is poured, clear liquid- liquor, or cerebrospinal fluid. The spinal cord is immersed in it - an appendage of the brain, resembling a pigtail. The spinal cord is connected with countless nerve fibers different bodies body. The lower end of the spine is firmly attached to a ring of three bones - pelvis. He, in turn, rests on thin "columns" - the tubular bones of the legs. These "columns" rest on wide "plates" - the feet.
However, the foot is more like not a plate, but an arch. Its design is as complex as the cross-ribbed vaults of Gothic churches: the entire human leg is composed of 30 bones, and 26 of them went to the creation of the foot.
The top vertebra of the spinal column is called the atlas. Once upon a time, that was the name of a fairy-tale hero who held the vault of heaven on his shoulders. Like this titan, the first cervical vertebra- Atlas holds the head of a man. The skeleton of the head, or skull, consists of 24 bones, mostly of flat bone plates. The cranium folded from them is very strong: it is difficult to break through it. Its walls are covered with a thick web of connective tissue fibers. Inside it is the control center of the body - the brain, which rests on a liquid pillow. A few "floors" below the spine, the chest is suspended: a movable structure of 24 narrow, arcuately curved plates - the ribs - and one wide plank - the sternum. This bony framework protects the heart and lungs. With each breath, the chest rises; pushing her respiratory muscles. Volume chest cavity every time it increases by several liters.
The skeleton of the arms is attached to the chest. They are very mobile. Each of them is suspended from a flat triangular bone - the scapula, which is deeply pressed into the muscles of the back. The scapula is connected to the chest by a thin tubular bone protruding forward - the clavicle. She rests on her chest. The skeleton of the hand, like the legs, consists of 30 bones, of which 26 form the hand. With its structure, it reminds us that our ancestors lived on trees and they had to cling to branches and climb trunks. Like our distant ancestors, we are very mobile thumb hands, the remaining fingers are rather long and very firmly connected by the bones of the wrist.
What is bone made of?
Bone consists of a compact substance based on calcium and phosphorus, spongy substance, living bone cells - osteocytes, blood vessels and nerves. In the middle of the bone is the medullary cavity containing the bone marrow. In the bones of infants, as well as in some bones of an adult, the bone marrow produces new blood cells - red blood cells(erythrocytes), white blood cells (leukocytes), and platelets (platelets). This function of the bone marrow is vital, as red blood cells carry oxygen throughout the body, white blood cells protect against infections, and platelets are responsible for blood clotting. In addition, bones contain minerals necessary for normal operation body - 99% of all calcium is deposited in the skeleton.
Bones are alive
From birth, the bones gradually stretch and increase, reaching their final size by the age of twenty. Mineral salts, in particular calcium and phosphorus, are essential for bone development. Vitamin D is also necessary for growth, it is he who helps to retain calcium in the bones. A child who does not receive calcium and vitamin D can develop rickets, a disease common in developing countries.
The bones of the hands and feet are similar. Their great flexibility is provided by a complex of joints. The hand consists of 27 bones, which include 8 carpal bones, 5 metacarpal bones located between the carpal bones and the phalanges of the fingers, and 14 phalanges of the fingers. There are 26 bones in the foot: 7 tarsal bones (the bones located above the foot), 5 metatarsal bones (the bones between the tarsus and the phalanges), and 14 phalanges of the fingers.
Rib cage
The chest consists of twelve pairs of ribs that are attached to the spinal column: 7 pairs true ribs, 3 pairs of false ribs attached to the sternum (the bone located in front of the chest), and 2 pairs of oscillating ribs that are not attached. The chest contains the vital organs: the heart, lungs and liver.
vertebral column
The vertebral column, or simply the spine, is one of the main parts of the skeleton, because it serves as a support for the head and torso. The spine consists of 33 vertebrae: 7 cervical vertebrae located at the level of the neck, 12 thoracic vertebrae - in the upper and middle sections of the back, 5 lumbar vertebrae - in lower section back, 5 sacral vertebrae (at the level of the sacrum) and 4 (or 5) coccygeal vertebrae located at the level of the coccyx. The vertebrae are separated intervertebral discs, consisting of cartilage tissue and shock absorbing. In order not to damage the vertebrae, one should maintain a straight posture, develop the muscles of the back and abdomen, and avoid lifting objects that are too heavy. The main support of the human body, the spinal column can be subject to deformations, such as scoliosis. Scoliosis - a lateral curvature of the spine - occurs in girls eight times more often than in boys and occurs during the period of growth.
The cranium performs important function protecting the brain and senses. It consists of 8 bones: 1 frontal, 2 parietal, 2 temporal, 1 occipital, 1 sphenoid and 1 ethmoid bone. Facial department includes 14 more bones, including 2 bones of the upper jaw,
fractures
To heal a fracture, the two pieces of bone must be aligned exactly in their original position. The fracture area is then covered with plaster so that the bone can heal. In difficult cases, screws and plates are used to fix parts of the broken bone. Healing happens naturally: bone cells provide proteins and calcium to form new tissues that cover both parts of the broken bone, causing the bone to heal over time.
The longest bone of the skeleton - the femur - corresponds to a quarter of a person's height.
