Features of the structure of the human spine, its departments and functions, possible diseases with damage to bone structures and elastic elements. Anatomy of the spine

Why does a person need a spine? Just think about how important it is for the body. Indeed, in fact, this is a kind of body support, consisting of 32 or 34 vertebrae. All of them are connected to each other with the help of joints, ligaments, intervertebral discs. The latter are the so-called cartilages. It is important to know the structure of the spine, so that if problems arise with it, they can be eliminated in a timely manner.

anatomy and structure

This part of the human body is quite simple in structure, because it consists of only a few sections, each of which, in turn, includes a certain number of vertebrae (they are usually called starting from the top):

cervical region: consists of 7 vertebrae. It is important to note that the bone that is located on the back of the skull is not considered and is called the zero vertebra;
thoracic: consists of 12 vertebrae;
lumbar: consists of 5 vertebrae;
sacral: consists of 5 vertebrae, which in an adult fuse into the sacrum;
coccygeal region: consists of 3-5 vertebrae that fuse into one coccygeal bone.

Many of us have seen the human spine in the medical literature more than once. His photo clearly demonstrates that the vertebrae are interconnected by discs, articular processes, ligaments (by the way, they are located in front, behind and on both sides of the vertebral bodies). Such a diverse connection of the vertebrae provides the mobility to a person with which he was so generously endowed by nature. Everything is thought out to the smallest detail: ligaments are some kind of limiters that can hold the body, and the muscles around the spine provide it with maximum movement. If the load on them is great, there is back pain and general malaise.

What are the functions of the spine?

First you need to understand that each section of the spine performs certain tasks related to the normalization of the work of one or another part of your body. So, the functions of the human spine, divided into 5 departments:

The most important role in this case is played by the thoracic region, it is he, together with the ribs and the sternum as a whole, that forms the chest. I would like to clarify that the ribs are separate bones that are attached to the spine, as if being its continuation. The chest protects the organs and provides them with immobility. But due to the fact that there are joints between the ribs and the spine, we can freely inhale and exhale.
It is important that special pads in the form of disks are located between the thoracic and cervical regions. For example, due to the fact that there are cervical intervertebral discs, a person is able to tilt his head to both sides.

Now it is advisable to note the functions of the spine as a whole:

it serves as a certain shock absorber during falls, bumps, shocks;
the spinal cord is located in the spine, it is thanks to it that the body is a single whole (it connects the brain and all other parts of the body);
due to the fact that the human spine connects the whole body, the skeleton becomes rigid, and the head is easily held in an upright position;
contributes to the mobility of a person, which is necessary for him in life;
it is on the spine that all the main muscles and hips are held.

What is the function of the cartilaginous discs between the vertebrae?

To begin with, it would be nice to understand what an intervertebral disc is. In simple terms, this is a kind of layer between two adjacent vertebrae.

The shape is rounded, similar to a tablet. The structure of the intervertebral disc is very complex.

The center occupies which is a shock-absorbing element with every movement of the spine. This is because its structure is very elastic.

Note that the vertebrae, despite the mobility, do not move relative to each other at all. All due to the fact that the fibrous ring is located around the nucleus in the intervertebral disc. Its structure is not simple due to the large number of different layers. This ring contains many fibers. All this connects and crosses in three directions. Strong and durable. But due to the fact that the intervertebral discs tend to wear out over time, the fibers can gradually turn into scars. This disease is called osteochondrosis. By the way, it often causes severe pain. As a result, it can tear and then surgical intervention is unlikely to be avoided.

An interesting fact is that no vessels pass through the intervertebral disc of an adult. Some may object and ask the question of how he then eats. This process occurs due to the penetration of oxygen and nutrients from the vertebrae located nearby (namely, from the vessels that permeate them). Therefore, drugs that often strive to treat diseases associated with damage to the intervertebral discs are simply useless. Here it is better to resort to laser plastic surgery, then the effect will be one hundred percent.

Based on the above features of anatomy, we can conclude what function the cartilaginous discs perform between the vertebrae. Firstly, they protect the spine from injury during excessive physical exertion, falls, bumps, etc. Secondly, it is with the help of them that our body is flexible and able to actively move in different directions. It is important to know that the thickness of the intervertebral discs can be different. It all depends on the part of the spine in which they are located:

Neck: 5-6 mm;

Thoracic: the thinnest discs - 3-4 mm;

Lumbar: 10-12 mm.

Since the spine has a physiological forward curvature in the cervical and lumbar regions, it must be understood that here the intervertebral discs will be slightly thicker.

If you look closely at the photo of the spine, you can easily see that the diameter of the intervertebral discs is 2-3 mm larger than the vertebrae themselves. I wonder if you knew that the length of the human spine changes during the day. In the morning it is 1 cm more than in the evening. This is explained by the fact that during the day, under the influence of gravitational forces, the distance between the disks decreases, during the night everything returns to normal. By the way, why does the structure of intervertebral discs change with age? This happens due to the fact that their absorbency deteriorates, they wear out, the spine becomes prone to damage. To prevent this from happening, it is necessary to exercise as much as possible throughout your life, spend time in the fresh air and eat right. Thanks to such simple rules, the intervertebral discs are well saturated with oxygen. Then by old age there will be no talk of any intervertebral hernia.

Bends in the spine - is it normal?

Yes, the answer of the doctors is unambiguously positive.

With the help of them, a certain springy effect is formed, which contributes to walking, running, jumping and other physical exercises. After all, the main functions of the human spine are reduced to creating maximum mobility of the body. Just imagine if there was a straight human spine. His photo clearly demonstrates the opposite, it is clear that the vertebrae formed something like a wave:

lordosis in the neck - the spine in this place is somewhat arched forward;
kyphosis in the chest - the spine here is curved back;
lordosis in the lumbar region: back the spine arches forward;
kyphosis in the region of the sacrum: a slight backward bend is visible.

This is an absolutely natural form of the spine, and the curves are considered to be its physiological feature.

Facet joints: anatomy. intervertebral foramen

It is those processes that extend from the vertebrae that are called joints. Their anatomy is simple. In addition to the fact that the vertebrae are interconnected by intervertebral cartilage discs, the facet joints play the same role. These processes (look like some kind of arcs) are directed inward, as if looking at each other. At their end is articular cartilage. Its nutrition and lubrication is carried out due to the fluid present inside the joint capsule. It is with it that the processes of the joints end. The main function of the facet joints is to provide a certain mobility of the human body.

The intervertebral (foraminal) foramina are designed specifically for veins and nerve roots to pass through them. Their location is interesting: on both sides of each vertebra. They are formed with the help of articular processes, legs and bodies of two adjacent vertebrae.

How does the spine change with age?

Age anatomy and physiology is also characteristic of the spine. Although, it would seem, the spine is a rigid pillar, which is the basis of our entire body.

Of course, the structure of cartilage tissue allows us to perform various movements, but nevertheless, the spine is a strong foundation, and it is very strange that time affects it. Just want to note that this is a completely normal physiological feature of the human body. Throughout life, the human spine not only increases in length and gains a certain mass, but also undergoes significant changes:

during the first months of life, any child is in a horizontal position, his spine is straight. Then there is a transition to a vertical position, due to which the spine acquires its characteristic physiological curves in its sections (cervical, thoracic, lumbar, sacral);
over time, all cartilage tissue turns into bone. It is said that in this way the spine becomes stronger;

The structure of the intervertebral disc is also subject to significant changes.

Age anatomy and physiology of the human spine is characterized by two main indicators:

The growth of a person and the ratio of the proportions of his body throughout his life. There are certain average indicators that are considered normal and allow you to determine whether the spine is developing correctly. After all, in the first 20 years of a person's life, the spine grows at the fastest pace, which can cause various deviations and diseases. That is why the child in the first years of life must be shown to specialists for the prevention of various diseases.
Spine growth by segments on average per year. This indicator is calculated according to a special formula, it also allows you to evaluate the development of the spine.

Spinal motion segment

A person has a certain functional unit, which is a spinal motion segment. Essentially, it is the connection of two adjacent vertebrae along with ligaments, discs, joints and everything else. Thus, we once again designate the function of the cartilaginous discs between the vertebrae. They are a special mount that allows a person to make various movements. Also, the mobility of the spine is created due to the facet joints. Through special holes that pass on the side of the spine, nerve endings and blood vessels are pulled out. The spinal motion segment is a set of interconnected elements. Failure of one of them has many consequences. It can appear in two ways:

segmental blockade: neighboring vertebrae do not move, and the activity of the human body is carried out at the expense of other segments. In this case, pain often occurs;
segmental instability: the opposite situation, when movements between adjacent vertebrae are excessive. In this case, not only pain occurs, but the problem can also hide much deeper: nerve endings are affected.

Remember that any pain in the spine can occur either in one specific place, or all at once. In any case, the focus of the lesion can only be determined with the help of special studies and the advice of a competent specialist.

Nerve endings and spinal cord

The connection of the vertebrae also occurs inside the spine thanks to the spinal cord, the basis of the human central nervous system. Due to it (with the help of incoming signals from the brain), the work of the whole organism is regulated. The spinal cord is a large thread, consisting of a huge number of nerve fibers and endings. It is located in the so-called "dural sac", which is well protected from external influences by three different membranes (soft, web-like, hard).

Around it is constantly present cerebrospinal fluid. Each section of the spine, and accordingly, all the muscles, tissues, organs and systems located around, are regulated by a certain area of the spinal cord.

Muscles located near the spine and their functions

It has already become clear that the main functions of the spine are reduced to providing movement to a person. This is done thanks to the muscles that attach to the vertebrae. When we talk about back pain, we often do not even suspect that the problem is not at all in the spine or discs. In fact, a specific muscle may be pulled. But complications in the spine can also cause involuntary contraction of adjacent muscles, i.e. in fact, the reverse situation. When such a spasm occurs, lactic acid is produced in the muscle fibers (this is glucose oxidized), caused by the lack of oxygen access to the blood. Such pain is very familiar to pregnant women. They experience it in labor during contractions due to improper breathing. But one has only to relax a little, and the discomfort disappears, as the spasm disappears.

Problems with the spine

Initially, nature planned everything differently. After all, no one imagined that modern women and men would turn into motionless creatures in the same (and absolutely uncomfortable for them) position throughout the working day. The spine is numb, while experiencing an incredible load. But everyone knows one simple truth very well: movement is life, and it's hard to argue with that. Of course, there are still a huge number of problems in this system, which are caused by bad ecology, improper and unbalanced nutrition, wearing uncomfortable clothes and shoes, etc. Correcting the current situation is quite simple, you should follow a few simple tips:

regularly lead an active lifestyle. Physical culture and sports are the main assistants;
create comfort around you: comfortable furniture, clothes and shoes will help you relax during the working day;
prophylactically visit, for example, an orthopedist, who is able to identify problems with the spine during a visual examination. Especially, this applies to small children.

Another back pain may be due to the fact that the intervertebral discs have worn off. Modern doctors like to talk about it to almost everyone. But in reality, this rarely happens. Degeneration of the intervertebral discs can be caused by various reasons, including excessive physical activity and tissue aging. Treatment usually consists of surgery.

We have clearly understood what function the cartilaginous discs between the vertebrae perform. They provide proper movement to a person and, if possible, prevent damage to the spine. Do not think that the pain that suddenly arises in the spine will definitely go away on its own. It may calm down for a while, but this is only the first signal of big problems.

Do not be lazy to turn to experienced and competent specialists in a timely manner who will help you prevent the development of serious diseases in the spine. After all, it is the basis of our entire body! The health of the whole organism and that carefree old age that everyone dreams of so directly depend on it. Look after yourself and be healthy!

He who is not serious about his own anatomy is also not serious about his own health.

The structure of the spinal column

If wooden or concrete pillars each consist of a homogeneous material, then the spinal column is heterogeneous. Its main components are the vertebrae. Almost everyone knows about the existence of vertebrae. There are 32 or 34 of them: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral and 3 to 5 coccygeal. The size and shape of the vertebrae are different. But they all have a body and an arc, between which there is a vertebral foramen. The vertebrae follow in turn one after another: in the region of the sacrum and lower back they are larger, and the higher they are, the smaller they are. A bit like a children's pyramid, only the rings strung on a children's toy have an absolutely regular rounded shape, and the vertebrae have protrusions - processes: articular, transverse and spinous.

The rings of the children's pyramid, lying one on top of the other, form a through hole, the vertebrae of our pyramid do the same. But this is not a simple hole - this is the spinal canal! A much more important thing passes through it than a polished stick of a toy pyramid - the spinal cord is laid through the spinal canal, the nerve endings of which transmit information to the brain, receiving response commands from it.

There are no toys here. It is better to think again about the pole - a concrete pole of a power line that supports a wire that powers some kind of control center.

But important communications are laid not only inside the spinal column.

The vertebral artery passes through the openings in the transverse processes of the cervical vertebrae.

The structure of the ligaments, muscles and joints of the spine

The spaces between the spinous processes of the vertebrae are occupied by ligaments and muscles.

The structure of the human spine. Articular processes, connecting with each other, form joints. In addition, the articular processes take part in the formation of the intervertebral foramens through which the neurovascular system of the spine passes.

But all this is not enough for our wonderful spinal column to function normally and smoothly. Its work is also provided by the intervertebral cartilages located between the vertebrae, which are called discs. They consist of a core and a fibrous, that is, fibrous, ring surrounding the core.

Spinal nuclei

Especially important for the life of the spine and, consequently, the life of the whole organism is the middle part of the disc - the nucleus pulposus. The nucleus has the appearance of a biconvex lens and consists of a gelatinous substance (hence its second name - the nucleus pulposus). The intervertebral discs of adults do not have vessels, therefore, the supply of nutrients to them and the removal of metabolic products occurs through the vertebral bodies through diffusion, that is, the penetration of particles of one substance into another when they come into contact.

Due to its elasticity, the core is an excellent shock absorber. Here you are lifting something heavy. Aggressive force begins to squeeze the vertebrae. The nucleus pulposus flattens as far as the elasticity of the annulus allows it, losing some fluid. But here you are lowering the load. The pressure on the disk becomes moderate, the suction forces begin to prevail over the compression forces, and the disk again actively accumulates water. After a while, the suction forces decrease and balance is restored again.

The gelatinous core of the disk has another wonderful feature: it is able to suck in water even with significant compression forces, to work in defiance of them.

But the strength and endurance of the core are not infinite. Intervertebral discs in the structure of the human spine, these wonderful shock absorbers, like any other mechanism, have their own service life. Studies have established that in a child, the nucleus pulposus of the intervertebral disc contains 88% of water, at 14 years old - 80%, and at 77 years old - 69%. This clearly confirms the fact known to everyone from their own experience: over the years, the spine becomes less hardy. In the language of science, the well-known truth looks like this: with age, the shock-absorbing ability of the nucleus under the influence of tensile and compression forces decreases. The gelatinous substance is no longer able to retain and absorb water under heavy loads. Old age is not joy. However, it is natural, you can’t get away from it anywhere. The nuclei are aging, the exchange of fluid between the vertebrae and fibrous rings is difficult ...

Fibrous rings of the spine

So we got to the fibrous rings of the structure of the human spine. Each of them, surrounding the nucleus of the intervertebral disc, consists of dense bundles of connective tissue, intertwined in different directions. These longitudinal, vertical, oblique and spiral weaves give strength and mobility to the connection of adjacent vertebrae. In addition, the fibrous ring helps the nucleus, protects it, taking on part of the load.

And this help is by no means superfluous - after all, the load is oh, how great! Let's not talk about athletes and accelerators, let's imagine a person with a height of 165 cm and a weight of 60 kg. It would seem - what is 165cm by 60kg! But when this person just stands straight with his arms at his sides, his lower lumbar disc experiences a load of 30 kg.

But then he held out his hands. Keep them horizontal. The disc was somewhat tense: the load increased to 66kg.

Let's give him something. It doesn't matter what. Suppose something weighing 10kg. The disk groaned - now 206kg is being pressed on it!

And the person puts the load aside and leans slightly. In this case, the load on the disk reaches 60 kg.

The person leans even lower, the angle between the torso and legs reaches 90 ° - and now 210 kg are already being pressed on the disc, that is, compared with a simple standing, the load has increased seven times! And if at the same time a person held in his hands, say, a thirty-kilogram load, then the compression force of the disk would increase to 480 kg!

And if he did not just hold the load, but lifted it, then the pressure would increase many times more. But our spine can handle this too. Overpower thanks to the vertebrae, the nuclei of the intervertebral discs, the fibrous rings, on which part of the load is redistributed, the joints and, of course, thanks to the ligaments and muscles.

But here's what's interesting. If a person leans forward so that his fingertips can reach the floor, the force squeezing the lumbar discs becomes much less than if he were standing in a position corresponding to the correct posture. This surprising circumstance is explained by the fact that in the position of a deep inclination, the muscles that hold the body in a vertical position or close to that are switched off from work. The body seems to hang on stretched muscles and ligaments, which does not lead to any significant increase in intradiscal pressure: if the muscles are not contracted, but stretched, they do not pull adjacent vertebrae together.

From what has been said, it follows that deep bends are useful, and half bends are harmful. This applies to both the cervical and lumbar regions. Otherwise: deep bends heal, and half bends cripple!

We will talk later about the tremendous positive value that stretching has for muscles. And now let's talk about the importance of muscles and ligaments for the well-being of the spinal column.

What parts does the skeleton consist of?

What are the functions of the skeleton?

Skeleton of the head, torso, upper and lower limbs.

Support, protective.

1. What are the features of the bones of the skull.

The skull protects the brain and sense organs from various injuries. The bones of the skull are flat, strong, they are connected to each other by sutures. A suture is a strong, immovable connection of bones.

2. Name the only movable bone of the skull and indicate how it connects to it.

Only one bone - the lower jaw - is movably connected to the rest of the bones. This allows us not only to grab and chew food, but also to talk.

3. How is the human skull different from the chimpanzee skull?

In humans, unlike mammals, the cerebral region is better developed, which is associated with an increase in brain volume.

4. List the bones related to the brain and facial parts of the skull.

The cerebral part of the skull consists of the frontal, occipital, two parietal and two temporal bones. The facial region includes various large and small bones, including paired zygomatic and nasal bones, unpaired maxillary and mandibular bones. On the jaws there are cells for teeth. In the lower part of the skull there are several small holes and one large one - a large occipital foramen. Through a large occipital foramen, the brain is connected to the spinal cord, and blood vessels pass through small holes.

5. Why are the cervical vertebrae less massive than the lumbar ones?

The more stress the vertebrae experience, the more massive they are. Therefore, the lumbar vertebrae are much larger than the cervical ones.

6. What is the structure of a vertebra and what role do cartilaginous intervertebral discs play?

Each vertebra consists of a massive part - a body and an arch with several processes. The vertebrae are arranged one above the other so that their openings coincide, and a vertebral capal is formed, in which the spinal cord is located. The spine protects the delicate spinal cord from injury. Between the vertebrae are intervertebral cartilage discs. Thanks to them, a semi-movable connection is formed. Cartilage is elastic and can stretch and harden. When we sleep, its thickness increases, and when we walk, it decreases. As a result, a person is taller in the morning than in the evening.

7. What bones belong to the chest? Why are the ribs connected to the sternum in a semi-movable way?

The chest is located in the upper part of the body. It is formed by the sternum (the middle part of the anterior chest wall), 12 pairs of ribs and the thoracic spine. The chest protects the heart and lungs located in it from damage. Ten pairs of ribs are mobile (joints) connected to the vertebrae and semi-mobile (cartilages) to the sternum. The two lower pairs of ribs are not connected to the sternum (they are articulated only with the vertebrae). This allows all the ribs to rise and move apart when inhaling, which increases the volume of the chest cavity and ensures the flow of air into the lungs, and when exhaling - to fall and push the air out of them.

Question 1. What is the structure and purpose of the 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 the initial sections of the digestive and respiratory systems.

In the skull, a large brain and a smaller facial section are distinguished. The brain part of the skull is formed by the following bones: unpaired - frontal, occipital, sphenoid, ethmoid and paired - parietal and temporal. The largest bones of the facial section are paired zygomatic, maxillary, as well as nasal and lacrimal bones, unpaired - the lower jaw and the hyoid bone located on the neck.

Question 2. Why are the bones of the skull connected motionless?

Because the skull protects the brain and sensory organs from external damage. And if the bones of the skull are movably connected, then the brain and sense organs will not be fully protected.

Question 3. What bones form the cerebral part of the skull?

The brain part of the skull is formed by the following bones: unpaired - frontal, occipital, sphenoid, ethmoid and paired - parietal and temporal.

Question 4. What role do spinal curvatures play?

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.

Question 5. What departments does the limb skeleton consist of?

The skeleton of any limb consists of two parts: the girdle of the limbs and the skeleton of the free limb. The bones of the limb girdle connect the free limbs to the skeleton of the body.

Question 6. What bones form the skeleton of the girdle of the upper limbs?

The girdle of the upper limbs is formed by two shoulder blades and two collarbones.

Question 7. What is the structure of the hand?

The brush is formed by a large number of small bones. It distinguishes three sections: the wrist, metacarpus and phalanges of the fingers.

Question 8. How is the structure of the lower leg and forearm similar?

The lower leg and forearm are formed by two bones. The bones of the lower leg include the tibia and fibula. The forearm is formed by the radius and ulna.

Question 9. What is a bony pelvis?

The bony pelvis is the two pelvic bones that connect to the sacrum. The pelvic bones together with the sacrum form a ring on which the spinal column (torso) rests.

Question 10. What parts does the skeleton of the free lower limb consist of?

The skeleton of the free lower limb consists of the femur, lower leg and foot bones.

THINK

1. In connection with what does a person have curves of the spine?

The spine has four bends, as a result of which its profile contour forms a wavy line. The bends facing forward with a bulge are called lordosis, and those turned with a bulge back are called kyphosis. There are cervical and lumbar lordosis, and thoracic and sacral kyphosis. The natural curves of the spine act like a spring. Due to these bends, elastic deformations occur in the spine (in response to the action of gravity) and wave shocks during walking or running.

Both kyphosis and lordosis are physiological phenomena. They are associated with the vertical position of the human body (upright walking).

2. How does the human skeleton differ from the skeleton of mammals?

In mammals, the spine is divided into five sections: cervical, thoracic, lumbar, sacral, and caudal. Only cetaceans do not have a sacrum. The cervical region almost always consists of seven vertebrae. Thoracic - from 10-24, lumbar from 2-9, sacral from 1-9 vertebrae. Only in the caudal region, their number varies greatly: from 4 (in some monkeys and humans) to 46.

Real ribs articulate only with the thoracic vertebrae (rudimentary may be on other vertebrae). In front, they are connected by the sternum, forming the chest. The shoulder girdle consists of two shoulder blades and two collarbones. Some mammals do not have clavicles (ungulates), in others they are poorly developed or replaced by ligaments (rodents, some carnivores).

The pelvis consists of 3 pairs of bones: iliac, pubic and ischial, which are tightly fused together. Cetaceans do not have a true pelvis.

The forelimbs serve as mammals for movement on the ground, swimming, flight, grasping. The humerus is greatly shortened. The ulna is less developed than the radius and serves to articulate the hand with the shoulder. The hand of the forelimb consists of the wrist, metacarpus and fingers. The wrist consists of 7 bones arranged in two rows. The number of metacarpus bones corresponds to the number of fingers (no more than five). The thumb consists of two joints, the rest - of three. In cetaceans, the number of joints is increased.

In the hind limbs, the femur in most mammals is shorter than the tibia.

The structure and shape of the vertebrae

Vertebral column (columna vertebralis) ( rice. 3, 4 ) - the real basis of the skeleton, the support of the whole organism. The design of the spinal column allows it, while maintaining flexibility and mobility, to withstand the same load that an 18 times thicker concrete column can withstand.

The spinal column is responsible for maintaining posture, serves as a support for tissues and organs, and also takes part in the formation of the walls of the chest cavity, pelvis and abdominal cavity. Each of the vertebrae that make up the spinal column has a through vertebral foramen (foramen vertebrale) inside ( rice. 8). In the spinal column, the vertebral foramina make up the spinal canal (canalis vertebralis) ( rice. 3), containing the spinal cord, which is thus reliably protected from external influences.

In the frontal projection of the spine, two sections are clearly distinguished, differing in wider vertebrae. In general, the mass and size of the vertebrae increase from the top to the bottom: this is necessary to compensate for the increasing load carried by the lower vertebrae.

In addition to the thickening of the vertebrae, the necessary degree of strength and elasticity of the spine is provided by several of its bends lying in the sagittal plane. Four multidirectional bends, alternating in the spine, are arranged in pairs: the bend facing forward (lordosis) corresponds to the bend facing backward (kyphosis). Thus, cervical (lordosis cervicalis) and lumbar (lordosis lumbalis) lordosis correspond to thoracic (kyphosis thoracalis) and sacral (kyphosis sacralis) kyphosis (Fig. 3). Thanks to this design, the spine works like a spring, distributing the load evenly along its entire length.

How many vertebrae? In total, there are 32–34 vertebrae in the spinal column, separated by intervertebral discs and somewhat differing in their structure.

In the structure of a single vertebra, the vertebral body (corpus vertebrae) and the vertebral arch (arcus vertebrae), which closes the vertebral foramen (foramen vertebrae), are distinguished. On the arch of the vertebrae there are processes of various shapes and purposes: paired upper and lower articular processes (processus articularis superior and processus articularis inferior), paired transverse (processus transversus) and one spinous (processus spinosus) process protruding from the arch of the vertebra back. The base of the arc has the so-called vertebral notches (incisura vertebralis) - upper (incisura vertebralis superior) and lower (incisura vertebralis inferior). Intervertebral foramen (foramen intervertebrale), formed by cuts of two adjacent vertebrae, open access to the spinal canal on the left and right ( rice. 3, 5 , 7 , 8 , 9 ).

In accordance with the location and structural features in the spinal column, five types of vertebrae are distinguished: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral and 3–5 coccygeal ( rice. 4).

The cervical vertebra (vertebra cervicalis) differs from others in that it has holes in the transverse processes. The vertebral foramen, formed by the arch of the cervical vertebra, is large, almost triangular in shape. The body of the cervical vertebra (with the exception of the I cervical vertebra, which has no body) is relatively small, oval in shape and elongated in the transverse direction.

At the first cervical vertebra, or atlas (atlas) ( rice. 5), the body is missing; its lateral masses (massae laterales) are connected by two arcs - anterior (arcus anterior) and posterior (arcus posterior). The upper and lower planes of the lateral masses have articular surfaces (upper and lower), through which the I cervical vertebra is connected, respectively, with the skull and the II cervical vertebra.

In turn, the II cervical vertebra ( rice. 6) is distinguished by the presence on the body of a massive process, the so-called tooth (dens axis), which by origin is part of the body of the first cervical vertebra. The tooth of the II cervical vertebra is the axis around which the head rotates along with the atlas, therefore the II cervical vertebra is called axial (axis).

On the transverse processes of the cervical vertebrae, rudimentary costal processes (processus costalis) can be found, which are especially developed in the VI cervical vertebra. The VI cervical vertebra is also called protruding (vertebra prominens), since its spinous process is noticeably longer than that of neighboring vertebrae.

Thoracic vertebra (vertebra thoracica) ( rice. 8) is distinguished by a large, compared with the cervical, body and an almost round vertebral foramen. The thoracic vertebrae have a costal fossa (fovea costalis processus transversus) on their transverse process, which serves to connect with the tubercle of the rib. On the lateral surfaces of the body of the thoracic vertebrae there are also upper (fovea costalis superior) and lower (fovea costalis inferior) costal pits, which include the head of the rib.

Rice. 8. VIII thoracic vertebra A - right side view;B - top view: 1 - upper articular process; 2 - upper vertebral notch; 3 - upper costal fossa; 4 - transverse process; 5 - costal fossa of the transverse process; 6 - vertebral body; 7 - spinous process; 8 - lower articular process; 9 - lower vertebral notch; 10 - lower costal fossa; 11 - arch of the vertebra; 12 - vertebral foramen

Lumbar vertebrae (vertebra lumbalis) ( rice. 9) are distinguished by strictly horizontally directed spinous processes with small gaps between them, as well as a very massive bean-shaped body. Compared with the cervical and thoracic vertebrae, the lumbar vertebrae have a relatively small oval vertebral foramen.

The sacral vertebrae exist separately until the age of 18–25 years, after which they fuse with each other, forming a single bone - the sacrum (os sacrum) ( rice. 10, 43 ). The sacrum has the shape of a triangle with its apex down; a base is distinguished in it (basis ossis sacri) ( rice. 10, 42 ), top (apex ossis sacri) ( rice. 10) and lateral parts (pars lateralis), as well as the anterior pelvic (facies pelvica) and posterior (facies dorsalis) surfaces. Inside the sacrum passes the sacral canal (canalis sacralis) ( rice. 10). The base of the sacrum articulates with the fifth lumbar vertebra, and the apex with the coccyx.

The lateral parts of the sacrum are formed by fused transverse processes and vestiges of the ribs of the sacral vertebrae. The upper sections of the lateral surface of the lateral parts have articular ear-shaped surfaces (facies auricularis) ( rice. 10), through which the sacrum articulates with the pelvic bones.

The anterior pelvic surface of the sacrum is concave, with noticeable traces of fusion of the vertebrae (they look like transverse lines), forms the posterior wall of the pelvic cavity.

Four lines marking the places of fusion of the sacral vertebrae end on both sides with the anterior sacral foramina (foramina sacralia anteriora) ( rice. 10).

The posterior (dorsal) surface of the sacrum, which also has 4 pairs of posterior sacral foramens (foramina sacralia dorsalia) ( rice. 10), uneven and convex, with a vertical ridge passing through the center. This median sacral crest (crista sacralis mediana) ( rice. 10) is a trace of fusion of the spinous processes of the sacral vertebrae. To the left and to the right of it are intermediate sacral crests (crista sacralis intermedia) ( rice. 10), formed by the fusion of the articular processes of the sacral vertebrae. The fused transverse processes of the sacral vertebrae form a paired lateral sacral crest (crista sacralis lateralis).

The paired intermediate sacral crest ends at the top with the usual superior articular processes of the 1st sacral vertebra, and below with the modified inferior articular processes of the 5th sacral vertebra. These processes, the so-called sacral horns (cornua sacralia) ( rice. 10), serve to articulate the sacrum with the coccyx. The sacral horns limit the sacral fissure (hiatus sacralis) ( rice. 10) - exit of the sacral canal.

Coccyx (os coccygis) ( rice. eleven, 42 ) consists of 3–5 underdeveloped vertebrae (vertebrae coccygeae) ( rice. eleven), having (with the exception of I) the shape of oval bone bodies, finally ossifying at a relatively late age. The body of the 1st coccygeal vertebra has outgrowths directed to the sides ( rice. eleven), which are vestiges of the transverse processes; at the top of this vertebra are modified upper articular processes - coccygeal horns (cornua coccygea) ( rice. eleven), which connect to the sacral horns. By origin, the coccyx is a rudiment of the caudal skeleton.

Vertebral joints
	Sagittal section at the level of two lumbar vertebrae. 1-vertebral body; 2 - nucleus pulposus of the intervertebral disc; 3-anterior longitudinal ligament; 4-fibrous ring of the intervertebral disc; 5-upper articular process of the lumbar vertebra; 6-posterior longitudinal ligament; 7-intervertebral foramen; 8-yellow bunch; 9-articular capsule of the facet (intervertebral) joint; 10-interspinous ligament; 11-supraspinous ligament.

3. Movement of the spinal column

4. Age features of the spine

5. Chest

The chest is formed by the thoracic vertebrae, twelve pairs of ribs and the sternum - the sternum. The sternum is a flat bone in which three parts are distinguished: the upper one is the handle, the middle one is the body and the lower one is the xiphoid process.

Ribs are made up of bone and cartilage.

The structure of the chest

The structure of the sternum

The first edge lies almost horizontally. The anterior ends of the seven pairs of ribs are connected to the sternum with their cartilages. The remaining five pairs of ribs are not connected to the sternum, and the eighth, ninth and tenth pair are each attached to the cartilage of the overlying rib; the eleventh and twelfth pairs of ribs end freely in the muscles with their anterior ends. The chest contains the heart, lungs, trachea, esophagus, large vessels and nerves.

The chest takes part in breathing - thanks to rhythmic movements, its volume increases and decreases during inhalation and exhalation. The chest of the newborn has a pyramidal shape. Along with the growth of the chest, its shape changes. The chest of a woman is smaller than that of a man. The upper chest of a woman is relatively wider than that of a man. After illnesses, a change in the chest is possible: for example, with severe rickets, a chicken breast develops (the sternum sharply protrudes anteriorly).

Chest development

1 - cartilaginous thorax of a 4-week-old fetus 2 - chest of a 5 week old fetus 3 - chest of a 6 week old fetus 4 - newborn chest