Human skeleton layout diagram. human bone

Lesson topic

Human skeleton

Lesson Objectives

Continue to form schoolchildren's ideas about the structure of the human skeleton;
To consolidate students' knowledge about the human musculoskeletal system;

Lesson objectives

Continue to deepen the knowledge of students on the topic "Musculoskeletal system";
Focus the attention of children on the uniqueness of the structure of the human skeleton;
To consolidate the acquired knowledge through practical application, using reference materials and working with diagrams and tables;
Contribute to the formation of reflective qualities (introspection, self-correction);
Develop students' communication skills;
Favor the creation of a psychologically comfortable environment in anatomy lessons;
Raise students' interest in biology lessons.

Basic terms

The skeleton from the point of view of biology is such a biological system that is a reliable support for the human body.

The human skeleton in translation sounds like dried up, and denotes a set of hard bones in the body, which serve not only as a support for the body, but also for its individual parts, and also plays the role of protective functions of the body from various types of damage.

Bones are the components of the skeleton and its main elements.

Human skeleton

Even without studying anatomy, each of you knows that the human skeleton is made up of different bones, but what is its need ... We will try to figure this out together.

The skeleton is needed in order to support the body, protect the internal organs and keep the shape of the body. In addition to all of the above, strong muscles are attached to the skeleton.

First, thanks to the skeleton, a solid foundation is formed in which vulnerable parts of the body are located. It plays the role of a frame that is able to fix different parts of the body in a certain position. The bones of the chest act as protectors for the lungs and heart, and they have the ability to contract and expand as we breathe.

Secondly, the skeleton enables living beings to move. After all, nature was arranged in such a way that the skeleton consists of different bones, each of which has its own specific shape and performs a specific role in the human body. The mobility and flexibility of the skeleton to our body provide joints, cartilage and ligaments.

The number of bones in the human skeleton can be discussed for a very long time, since it is not the same for different people. Basically, the majority of the adult generation has more than 200 bones in the body. But it should be noted that there are people who are owners of an extra pair of ribs, others also have deviations in the number of vertebrae, and the skeleton of a newborn child has more than 350 types of bones. In addition, with age, some bones have the ability to grow together, and their number decreases. Therefore, it makes no sense to assert about a specific number of human bones, since it is not possible to make an accurate count.

Exercise:

1. Can human bones grow throughout life?
2. Why do bones sometimes lose their strength?
3. What should be done so that the bones do not lose their elasticity?

Organization of the skeleton

The human skeleton, like all vertebrates, is divided into an axial and accessory skeleton. The first includes all the bones that are located in the middle and create the skeleton of the body. These include all the bones of the head, neck, spine and ribs with the sternum. And the additional or peripheral skeleton includes the bones of the scapula, collarbone, as well as the bones of the upper and lower extremities.

Axial skeleton

Now let's take a closer look at the human axial skeleton.

Scull

The components of the skull are the bone base of the head, which protects the human brain and its organs of vision, hearing and smell. The skull is subdivided into the brain and facial sections and consists of flat and immovable bones, with the exception of the bones of the lower jaw.

To see what bones the brain and facial sections are made of, carefully consider the picture above.

And now look at the connection of the bones of the skull:

Exercise:

1. Name the bones that form the brain section?
2. Which of the bones of the skeleton of the skull are unpaired, and which are paired bones?
3. Name the largest bones that are located in the facial region.
4. Name all the bones that belong to the axial skeleton.
5. Which bone of the skull is immobile?

Torso skeleton

The skeleton of the human body consists of the chest and the spinal column. The thorax is the bone base of the chest, behind which the internal organs are hidden, and it consists of the sternum, twelve thoracic vertebrae and ribs.

The ribs of the human skeleton look like flat curved arcs, the posterior ends of which are connected to the thoracic vertebrae, and the anterior ones are connected to the sternum with the help of cartilage. Such fastening of the ribs to the skeleton creates conditions for the mobility of the chest during human breathing.

The spinal column is the main axis of the body, which is designed to support the human skeleton and is the main axis of the body. Inside the spine is the spinal cord.

The spinal column consists of 33-34 vertebrae, which is about forty percent of the length of the human body.

Four bends act as shock absorbers of the spine, which protect the internal organs and the brain, and soften shocks while walking, running and jumping.

peripheral skeleton

The accessory skeleton, or, as it is also called peripheral, consists of the skeleton of the limbs and is divided into the skeleton of the lower and upper limbs. The upper section includes the shoulder girdle and limbs, and the lower part includes the pelvic girdle with its limbs.

Since the free limbs are securely attached to the bones of the belt and have good mobility, they are able to withstand considerable loads.

Naturally, the upper and lower limbs have different functions. The upper ones provide a person with the opportunity to perform various movements and operations, while the lower ones are needed for movement and support.

Upper limb belt

The upper belt consists of the shoulder blades and collarbones. And the skeleton of the upper limbs is divided into the bones of the shoulder, forearm and hand.

Belt of the lower extremities

The pelvic girdle consists of three rigidly interconnected bones. In each such bone there is a spherical cavity, into which the head of the bone of the lower limb enters. The fixed bones of the girdle of the lower extremities, fused with the sacrum, provide the human body with reliable protection of the internal organs and allow it to withstand enormous physical exertion.

Skeleton of the lower extremities

If we consider the skeleton of the lower extremities, we can see that it consists of the femur, bones of the lower leg and foot. The femur and tibia have an anterior joint in the form of a patella, which provides mobility to the knee joint.

Homework

Look carefully at the drawing of the human skeleton and sign its digital designations:

Give answers to the questions posed:

1. Name all the departments that make up the human skeleton.
2. Name the number of vertebrae in each of the sections of the spine.
3. What parts does the spine consist of?
4. What is the significance of the curves of the spine for the human body?

The human skeleton is a movable support of the body, to which movable muscles are attached. Without the bones of the skeleton, we would look like shapeless bags.

There are only 206 bones in the human body. The bones of the limbs, spine and pelvis are the support of the body. The bones of the skull, chest and pelvis protect the internal organs from damage. The bones are smooth and hard. But that's just outside. Inside they have a tubular structure and are filled with bone marrow.

Bones can break. Children have more plastic in their bones and fractures are rare. Older people have more mineral salts in their bones, they fracture more often, and the bones heal much more slowly than in children.

The skeleton, together with the muscles attached to it, participates in the movements of the body. Many bones of the skeleton are connected movably with the help of joints and ligaments. Thanks to the flexible joints of the bones, you can run and jump. Cartilage covers the surfaces of articulating bones at the joints, and in some places - in the ears, nose, between the sternum and ribs - is part of the skeleton.

The spine consists of 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae, 5 fused sacral vertebrae, and 3-4 coccygeal vertebrae. In total, there are 32-33 vertebrae in the spine, and they are the most tender in the whole body. Connected by ligaments and muscles that are attached to the bone processes of the vertebrae and separated by intervertebral discs. The human spine has four curves, which take some of the load off the vertebrae and allow us to stand straight and walk on two legs, and not on four, as almost all animals do. The curves also soften the bumps that come with running.

The skull consists of 22 bones connected to each other and protecting the brain from damage. All bones of the skull, with the exception of the lower jaw, are connected to each other with the help of ossified sutures formed by dense tissue. The lower jaw is movable, which allows us to open and close our mouth. There are also 3 pairs of auditory ossicles in the skull.

The lower limb consists of the thigh, lower leg and foot. The joints that connect the bones of the lower limbs allow us to run and jump.

The skeleton of the upper limbs consists of the shoulder girdle and the skeleton of the arms. The shoulder girdle is the shoulder blades on the back side and the collarbone on the front, one end of which is connected to the sternum - the bone that makes up the central part of the chest. The arm skeleton includes the humerus, forearm bones, and arm bones.

There is only one bone (hyoid) that is not connected to the general skeleton.

The crown is the place on the head where the three main bones of the skull converge: two parietal and one frontal. If a book is placed on the head of a standing person, the book will lie on the crown of the head. In young children, the connective tissue in this place does not ossify for a long time and remains soft. Ossification ends in the second year of life.

To avoid curvature of the spine, it is necessary to constantly monitor your posture and avoid incorrect body positions or uncomfortable postures, for example, while doing homework or sleeping.

Children are interested in how the world works and everything in it. Their curiosity makes no exception for humans. They are interested in how a person works, how he sees and hears, runs and jumps. About the human skeleton, which you can’t see, like skin or eyes, with the naked eye, modern children learn from cartoons and comics. This makes the skeleton in the eyes of the child even more interesting.

But the human skeleton with the name of the bones and muscles in cartoons and comics can not be found, and it will not hurt children to memorize them little by little.

Knowing how complex and fascinating the human body is, will awaken in the child an interest in biology, medicine, and will encourage a more conscious approach to their own health and the health of others. Finally, this knowledge will be useful to him at school, where already in the elementary grades they get acquainted with the structure of man.

The skeleton and muscles are the frame that determines the shape of a person, protects his internal organs and allows him to move. If not for the skeleton, then the person would be like a shapeless jellyfish. Muscles are attached to the skeleton and provide our every movement - from fluttering eyelashes to lifting weights.

Bones are composed of organic and inorganic substances, the former of which provide them with flexibility, and the latter with strength. Thanks to this, the bones are unusually elastic and strong. The complex structure adds strength and flexibility to them at the same time. Any bone consists of several layers.

The outer one is made up of strong bone tissue.
The next connecting layer covering the outside of the bone.
Loose connective tissue containing blood vessels.
At the ends is cartilage tissue, due to which bone growth occurs.
Another layer is the nerve endings, through which signals are transmitted from the brain and back.

Bone marrow is enclosed inside the bone tube, which also comes in two forms. Red is involved in hematopoiesis and bone formation. It is full of blood vessels and nerves. Yellow is responsible for the growth and strength of bones. We see that the skeleton, in addition to everything else, contributes to the renewal of blood. This is where blood cells are born. If, due to illness, it ceases to perform this task, the organism dies.

In the organization of the skeleton, several groups of bones are distinguished. One of them is the main supporting structure of our body, which includes the spine, bones of the head and neck, chest and ribs. Together they form the axial skeleton. The second part is called the accessory skeleton and it includes the bones that form our arms and legs, and the groups of bones that provide their connection with the axial skeleton.

Skeleton structure

The bones of the head include the skull and bones of the middle ear. The skull contains and protects the brain. It consists of two sections: brain and facial. The first of which includes eight bones. There are fifteen of them in the front section.

Trunk bones

This part of the skeleton includes the chest and spine, starting from the neck. We unite them, since they are closely related both literally (the chest is attached to the spine), and by location, and by the tasks they solve. These are one of the largest human bones. Their function is to protect the heart, lungs, etc. Among them are the spinal column and chest.

vertebral column

The human spine is the main support of the whole body, its main axis. It is he who ensures our upright posture. The spinal cord provides communication between the upper and lower parts of the body. It distinguishes five departments, consisting of 32-34 vertebrae. They are called by their location - cervical, thoracic, lumbar, sacral and coccygeal.

Rib cage

The chest really looks like a cage, where 12 pairs of ribs play the role of a lattice behind which the heart, lungs, and vital organs are hidden. Closes its flat wide bone, which is called the sternum. In total, 37 bones belong to the chest.

Upper limb bones

So scientists and doctors call our hands. I don’t think it’s necessary to explain how much it means for a person to be able to perform both weight lifting and cross-stitching. But think about how different tasks they are called upon to solve. This explains their rather complex structure. The bones of the upper limb (VC) include the VC belt and the free part of the VC.

The belt includes the scapula and collarbone, connected by a ball joint to the humerus. This is where the muscles come in. In the free part of the upper limb, three sections are distinguished - the shoulder (humerus), forearm (radius and ulna) and the hand. Most of the bones in this particular area of the hand - twenty-seven, they are noticeably smaller than the bones of the forearm, and differ from them in shape.

Pelvic girdle

This belt provides a connection between the spine and lower extremities, and also accommodates and protects the organs of the digestive, urinary and reproductive systems. The pelvis is made up of three fused bones.

Bones of the lower limb

The skeleton of the leg resembles the structure of the hand. They are fundamentally the same, differing in size and some other details. Since it is the legs that bear the main weight of our body when moving, they are more powerful and stronger than the bones of the arm.

What are the shapes of bones

Depending on their functions in the human body, bones differ in shape. There are four types of bone shapes:

Wide or flat (for example, at the skull);
Long or tubular (mainly in the limbs);
Short, such as the bones of the wrist;
Asymmetrical, having a composite shape. These are the pelvic bones, vertebrae, etc.

Muscles of the head and face

Previously, only specialists could know the structure of a person, his skeleton and a list of muscles. Today, anyone who is interested in this topic can find a detailed anatomical atlas on the Internet, which provides a detailed description of the movements of our body and all its parts that provide this. The most important role in ensuring movements is played by muscles, organs consisting of a special elastic tissue capable of

contract under the influence of nerve impulses. There are over 640 different muscles in the human body. Among them, there are various types according to different parameters:

By the functions they provide;
In the direction of the fibers of which they are composed;
By form;
In relation to the joints.

Understanding all this is not so easy, so let's look at the muscles depending on where they are on our body.

When we talk about movement, we first of all imagine how our arms and legs work. Meanwhile, the muscles of the head and face also work hard, providing breathing, facial expressions, speech, and our nutrition. The strongest muscles in our body are the chewing muscles.

The facial muscles and muscles of the eye, unlike all the others, are not attached to the bones. This allows them to be particularly sensitive and guarantee even micro-movements. Thanks to this, we can convey both joy and sadness, the slightest change in emotions.

Neck muscles

This group of muscles allows us to turn around, bow, swallow something and speak, even breathe.

Trunk muscles

Muscles are attached to bones by tendons and perform various tasks. - provide mobility and the ability to maintain balance, fix the joints. According to their functions and modes of action, there are those that contract synchronously during work or synergists, and muscles that perform opposite actions (antagonists). Most often, actions occur due to the fact that some muscles contract and other muscles relax at the same time.

The muscles of the trunk include the superficial and deep muscles of the back and chest, oblique, rectus, etc. abdominal muscles.

Pelvic muscles

These muscles originate on the bones of the pelvis and spine, are attached to the upper edge of the thigh, and surround the hip joint. Among them, two groups are distinguished: internal and external.

Muscles of the upper limbs

Among this group of muscles, the same parts are distinguished as in the bones of the hand:

Muscles of the VK belt;
shoulder;
Forearms, providing flexion and extension of the forearm, hand and each finger.

Muscles of the lower limbs

Thanks to these muscles, a person walks and runs, swims or jumps. In order to provide such different actions, no single group of different muscles is required. These include the muscles of the thigh, lower leg and foot. This is a rather complex system, including muscles that are different in shape, the direction of the fibers, in relation to the joints and other things, mutually complementing each other.

Muscle Anatomy Muscle Physiology How Muscles Work

Skeleton(from the Greek skeleton - dried) of a person is a collection of bones connected in a certain way to each other. In an adult, the skeleton consists of approximately 205 bones. Three sections are distinguished in the skeleton (Fig. 12): the skeleton of the body, the skeleton of the skull and the skeleton of the limbs (Table 2).

Rice. 12. Human skeleton (front view):

1 - cerebral skull, 2 - facial skull, 3 - bones of the girdle of the upper limb 4 - humerus, 5 - bones of the forearm, 6 - bones of the hand, 7 - chest 8 - spinal column, 9 - bones of the girdle of the lower extremities, 10 - femur , 11 - leg bones, 12 - foot bones

Bones of body parts	Names of bones and their number
Trunk bones	Vertebrae - 31 - 33 cervical - 7 thoracic - 12 lumbar - 5 sacrum (5 fused sacral vertebrae) coccyx (3 - 5 coccygeal vertebrae) Ribs - 12 pairs Sternum
Skull bones	23 bones, including unpaired ones - frontal, occipital, sphenoid, lower jaw, hyoid bone and paired ones - parietal, temporal, zygomatic, etc.
Upper limb bones	32 bones in one upper limb clavicle scapula humerus radius carpal bones - 8 metacarpal bones - 5 phalanges of fingers - 14
Bones of the lower limb	31 bone in one lower limb pelvic bone femur patella tibia fibula tarsal bones - 7 metatarsal bones - 5 phalanges of fingers - 14

The skeleton of the trunk consists of the vertebrae that form the spine and the bones of the chest. Each segment of the skeleton of the human body is formed by a vertebra, and in the thoracic region also by a pair of ribs and a portion of the sternum.

The skeleton of the head - the skull, protects the brain, sensory organs and serves as a support for the initial sections of the digestive and respiratory organs. The skull is conditionally divided into two sections - cerebral and facial.

The skeleton of the upper and lower extremities is divided into the skeleton of the free limb and the skeleton of the girdle. The skeleton of the girdle of the upper limbs (shoulder girdle) consists of two paired bones - the scapula and the collarbone, and the skeleton of the free upper limb - of three sections: the humerus, the bones of the forearm and the bones of the hand.

The skeleton of the girdle of the lower extremities (pelvic girdle) consists of a paired pelvic bone, and the skeleton of the free lower limb is divided into three sections: the femur, the bones of the lower leg and the bones of the foot. Each bone is an independent organ that performs a specific function.

The bones of the skeleton differ in shape and structure. Distinguish tubular, sponge, flat, mixed and air bones(Fig. 13).

Rice. 13. Types of bones:

1 - long (tubular) bone, 2 - flat bone, 3 – spongy (short) bones, 4 – mixed bone

Tubular bones are divided into long (humerus, femur, bones of the forearm and lower leg) and short (bones of the metatarsus and tarsus, phalanges of the fingers). Bones, with the exception of the articular surfaces, are covered with a connective tissue sheath - periosteum, which performs bone-forming and protective functions. The periosteum is firmly fused to the bone with the help of connective tissue fibers that penetrate deep into the bone. The outer layer of the periosteum is coarse-fibred, consisting of intricately intertwined fibers and connective tissue cells. In this layer there are many blood and lymphatic vessels, nerve fibers that ensure the vital activity of the bone. The inner layer of the periosteum is thin, contains cells from which osteoblasts are formed - young bone cells. Due to the bone-forming function of the periosteum, the bone grows in thickness and fuses with fractures.

Inside the bones are medullary cavity(in tubular bones) and spongy cells, in which the bone marrow is located. In a newborn child and in childhood, the bone marrow cavities are filled with red bone marrow, which performs blood-forming and protective functions. From the stem cells of the red bone marrow, blood cells (erythrocytes, leukocytes) and cells of the immune system (lymphocytes) are formed. In an adult, red bone marrow is preserved only in the cells of the cancellous bone. Other bony cavities contain obese yellow bone marrow that has lost its function.

From the side of the medullary cavity and cells, the bone is covered with a thin connective tissue plate - endosteum, also producing bone tissue.

The bones of the skeleton and the whole skeleton perform supporting, motor protective functions. Bones are also a depot for mineral deposits - phosphorus, calcium, iron, copper and other trace elements.

Bone Strength It is ensured by the presence of organic and inorganic substances in them, as well as by the structure of bone tissue. In terms of hardness and elasticity, bones can be compared with bronze and cast iron. The compact and spongy substance of bones is built from bone tissue. Compact (dense) bone substance forms the outer layer of each bone. sponge substance, formed by bone crossbars (beams), is located under a compact substance. In tubular bones in the area of their body (diaphysis), the compact bone substance is thick (up to 1 cm). At the ends of tubular bones in flat and other bones, this layer is thin. The compact bone substance is permeated with a system of bone canals, in which blood vessels and nerve fibers are located (Fig. 14).

Rice. 14. Scheme of the structure of the tubular bone:

1 - periosteum, 2 - compact bone substance, 3 - layer of outer surrounding plates, 4 - osteons, 5 - layer of inner surrounding plates, 6 - medullary cavity, 7 - bone crossbars of cancellous bone substance.

Each bone channel (osteon channel) is surrounded by concentric plates in the form of 4-20 thin tubes inserted one into the other. The system of such tubules together with the tubule is called osteon, or haversian system(Fig. 15). The spaces between the osteons are occupied by intermediate, or insertion, plates, which, when the bone is restructured due to changing physical load, serve as material for the formation of new osteons. The surface layer of compact bone substance is represented by the outer surrounding plates, which are the product of the bone-forming function of the periosteum.

Rice. 15. The structure of the osteon in the section: 1 - osteon plates, 2 - bone cells (osteocytes), 3 - central canal (osteo canal)

The inner layer of the bone, bordering the medullary cavity, is formed by the inner surrounding plates and is covered with fibrous connective tissue - the endosteum.

spongy bone, located under the compact, is located at the ends of the tubular bones - the epiphyses, in the bodies of spongy, mixed bones, in flat and air bones. Spongy bone substance consists of bone crossbars that intersect each other in different directions. Their distribution corresponds to the direction of the main lines of compression (pressure) and tension acting on the bone (Fig. 16).

Rice. 16. Scheme of the location of the bone crossbars in the cancellous bone (cutting the upper end of the femur): 1 - lines of compression (pressure), 2 - lines of tension

Such an arrangement of the bone crossbars at an angle to each other ensures a uniform distribution of pressure and force of the muscles on the bones of the skeleton.

Bone is highly plastic. Depending on the magnitude of the load on the bones, the number of osteons increases or decreases, their location in the compact substance changes. With constant muscle load, sports, physical labor, the number of osteons and their size increase, the layer of compact bone substance in tubular and other bones thickens, and the medullary cavities narrow. The bone crossbars (beams) of the spongy substance also thicken, acquire a more complex structure (branch). The bones become thicker and stronger. With a decrease in physical (muscular) load, with a sedentary lifestyle, prolonged bed rest during illness, the bones become thinner, weaker.

Bone strength is also provided by organic and inorganic substances. Organic substances give bones flexibility and elasticity.

Inorganic substances (calcium phosphate, calcium carbonate and other salts) give bones hardness. In living bone, organic matter accounts for about 60% of its mass, the rest belongs to inorganic compounds.

The effect of organic and inorganic substances on the strength properties of bones can be verified experimentally. After removing organic matter by roasting the bone in a fire, it becomes brittle. Removal of inorganic substances (salts) from the bone by keeping the bone in acid makes the bone soft and flexible. The combination of the hardness of inorganic compounds with the elasticity of organic compounds provides bone strength.

Similar information.

Everyone knows about the existence of bones in our body. Being a solid skeleton, the skeleton (from the Greek “skeleton” - “dried”, “dried”) performs various functions in our body, the main of which is supporting: it holds all organs in a certain position, takes on the entire weight of the body. And together with muscles and connective tissue formations - cartilage, ligaments, tendons - it gives us the ability to move, creates the structural shape of the body, determines its size. In addition, bones, muscles and ligaments serve as a reliable shell for internal organs and tissues hiding in the body. In Figure 1 you can view the human skeleton.

Rice. 1. Human skeleton.

The human skeleton is made up of interconnected bones. Bone tissue in the total body weight is 10–15 kg (in men, somewhat more), i.e. makes up 1/5–1/7 of the human body weight. It is not possible to specify the exact number of bones in the human body. First, it is somewhat different for different people. Approximately 20% of people have abnormalities in the number of vertebrae. One person out of every 20 has an extra rib, and this occurs in men about three times more often than in women (contrary to the biblical legend about the creation of Eve from Adam's rib). Secondly, the number of bones changes with age: over time, some bones fuse together, forming tight sutures. Therefore, modern scientists carefully point out that a person has “somewhat more than 200 bones”, and in the body of a child there are about 300. Each bone has a certain shape, size and occupies a certain position in the skeleton. Part of the bones are interconnected by movable joints, which are set in motion by the muscles attached to them.

Watch video 1.

Guys, watch the video.

The human skeleton is divided into the axial skeleton and the peripheral skeleton. Figure 2.

Rice. 2. Scheme of the structure of the human skeleton

Axial skeleton. Head skeleton (skull)

It 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 the initial sections of the digestive and respiratory systems.

In the skull, a large cerebral and smaller facial (visceral) sections are distinguished. The medulla is formed by bones: unpaired - frontal, occipital, sphenoid, ethmoid and paired - parietal and temporal.

The largest bones of the facial region - paired zygomatic, maxillary, nasal, lacrimal and unpaired - the lower jaw and the hyoid bone located on the neck.

You can see the skeleton of the skull in Figure 3.

Rice. 3. Skeleton head

Figure 4 shows the connection of the bones of the skull

Rice. 4. Connection of the bones of the skull

We will see the model of the human skull in video 3

Torso skeleton

The skeleton of the body consists of the spine and thoracic cells. Figures 5 and 6, respectively.

The spine connects parts of the body, performs a protective function for the spinal cord and supports the head, arms and torso. The length of the spine is 40% of the length of the human body. The spine is formed by 33-34 vertebrae. The following sections are distinguished in it: cervical (7 vertebrae), thoracic (12), lumbar (5), sacral (5) and coccygeal (4-5). In an adult, the sacral and coccygeal vertebrae fuse into the sacrum and coccyx. In humans, the coccygeal vertebrae are the least developed. They correspond to the caudal vertebrae of the animal spine.

Rice. 5. Spine

The spine has 4 bends that play the role of shock absorbers: 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. A 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 foramina form the spinal canal, in which the spinal cord is located.

Now, guys, try to complete the task on your own ( Create a copy of the document first. Sign the document with your first and last name).

The structure of the cervical vertebrae

The thorax is formed by 12 pairs of ribs, the thoracic vertebrae and a flat sternum - the sternum. The ribs are flat, curved bones. their posterior ends are movably connected to the thoracic vertebrae, and the anterior ends of the 10 upper ribs are connected to the sternum with the help of flexible cartilage. This ensures the mobility of the chest during breathing. The two lower pairs of ribs are shorter than the rest and terminate freely. The chest protects the heart, lungs, liver, stomach and large vessels from damage.

Rice. 6. Chest

Upper limb belt

Formed by two shoulder blades and two collarbones. The skeleton of the upper limb (Figure 7) consists of three sections: the humerus, the bones of the forearm (radius and ulna) and the hand (3 sections - the wrist, metacarpus, phalanges of the fingers). The humerus forms a movable joint with the scapula (shoulder joint), which allows you to perform various movements.

Rice. 7. Upper limb skeleton

Belt of the lower extremities

The girdle of the lower extremities (pelvic girdle) consists of three bones that are fixed to each other, fused with the sacrum, which allows them to withstand heavy physical exertion and perform a protective function for internal organs. In each pelvic bone there is a spherical cavity, which includes the head of the bone of the free lower limb.