The structure of the spinal cord. Detailed description of the structure and functions of the spinal cord

The spinal cord is the most important part of the central nervous system, located along the spine in a special channel. It resembles an oblong body of a light shade, angular in its final parts above and below and rounded in the middle fragment. In the upper part, the spinal cord becomes the support of the brain, and in the lower part it ends in a thickening called the truncated cerebral cylinder. In adults, the spinal cord is much shorter than the spinal column and rarely exceeds 45 centimeters.

The spinal cord has a number of thickenings that play an important role in the functioning of the central nervous system. Among them stands out:

• thickening in the cervical region - located in the area of ​​the third cervical and first thoracic vertebral discs;
• lumbar thickening - located at the level of the last thoracic vertebrae.

The spinal cord is divided into two approximately equal longitudinal parts. This function is performed by the posterior median groove and the convex median fissure. On a surface spinal cord in the locations where the anterior and posterior roots emerge, there are two less noticeable slits: posterior and anterior. The part of the spinal cord located opposite two pairs of roots, each of which consists of two anterior and two posterior ones, has its own name - a segment.

Structure and characteristics

The structure of the spinal cord is studied through careful diagnostics. It should be noted that scientists call its main functional part the spinal nerve filaments. They are represented by 31 pairs, which can be characterized as nerve nodules that stand out from their areas.

The anterior node is composed of axons of motor neurons of the nuclei of the anterior regions of the gray matter. The anterior nodes of the eighth cervical, twelfth thoracic, and two lower cingulate fragments, together with the processes of somatic motor neurons, include fragments of the paravertebral nodes of the third columns, and the anterior nodes of the posterior fragments include zones of neurons of the sympathetic centers of the median substance of the spinal cord. The posterior node provides its integrity with central fragments of nerve filaments, which are localized in the cylinders of the spinal cord. At the same time, in the gray matter of the main sections there is a central segment, which, gradually thickening, reaches the fourth ventricle of the brain, and in the second zone of the nerve thickening it ends in the terminal ventricle.

The structure and functions of the spinal cord are inseparable. The gray matter, mainly composed of nerve plexuses, rests on nerve centers. In a vertical section, these centers are shaped like butterfly wings, the belts of which form the horns of the spinal cord. The anterior horn is slightly enlarged and located in top point spinal tail. The dorsal horn is composed of a narrow fibrous sphere of gray matter, which extends almost to the border fragments of the spinal cord. The middle gray fluid makes up the lateral horn.

Scientists call the vertical zones of gray matter pillars. The posterior and anterior columns circulate exclusively in the spinal cord. The lateral column is slightly shorter in length, its beginning approximately coincides with the level of the eighth cervical sector and extends to the anterior lumbar fragment. In columns of gray liquid, nerve cells collide in the form of clear groups - nuclei. Cerebrospinal gelatinous fluid circulates around the longitudinal canal.

White matter structure

The white matter covers the outer sectors of the spinal cord and is composed of axons of nerve ganglia, which provide the load-bearing function of the spinal cord. The hollows that are the main distinctive feature separate trunk of the spinal cord, delimiting the white matter into tracts in directions. Nerve threads, related in etiology and purpose, in the white matter are connected into plexuses or cords, which have a clear separation and occupy a strictly defined position on local planes.

The human spinal cord has three systems of connecting tracts: short, motor and sensory. Short plexuses solder fragments of the nerve filaments of the spinal cord to each other. Sensory connections go up to the brain area. The motor filaments are responsible for connecting the brain with the spinal portion of the nervous system. This circuit is inextricably linked with nerve nodes in other centers.

Along the entire length of the spinal cord there are arteries that supply it with blood: the odd spinal artery and the even-numbered posterior spinal artery, which form between the main modular arteries. Superficial blood flows provide communication with each other through vertebral connections.

The spinal cord is covered by a strong covering of the hardened medullary surface, the processes of which, diverging at any of the intervertebral joints, cover the nodule, as well as the spinal center, which performs current tasks. The area between the hardened coating and the vertebrae is densely filled small vessels and human fat layer. In addition to the hardened bone chamber, the spinal cord is closed by the middle and softened brain surfaces. Between them there is a special cavity where spinal fluid circulates.

There are two defining functions of the spinal cord: impulse and conduction. The posterior nodes of the spinal cord transmit sensitive signals tending to the center, and the anterior ones provide the passage of motor signals, which, on the contrary, tend from the center.

Research methods

Stretch reflexes are usually accompanied by contraction of muscles in response to their irritation when exposed to a special hammer.

They are distinguished by local manifestations, and based on their presence or absence, the etiology of spinal cord injury is diagnosed. Of particular importance is the study of external and deep reflexes. If the sectors are damaged, sensitivity in these areas decreases, and problems with spinal reflexes begin. Based on the state of motor function of the limbs, muscle tension, changes in ascending reflexes, and the presence of pathologies in the hands and feet, the performance of the direct functions of the spinal cord can be assessed.

To clarify the symptoms of the pathology and its relationship with neighboring tissues, as well as to clarify the nature of the disease process, additional diagnostics are carried out. It includes the study of bioelectric potentials, as well as electrophysiological study of the functions of muscles and damaged nerves, which makes it possible to measure the speed of impulses by various types motor nerve fibers.

Using X-ray examination, damage to the spine and surface of the spinal cord is diagnosed. Together with surface radiography, if necessary, a tomogram is made, which allows you to find out the structure of the vertebral discs and the dimensions of the internal canal.

The spinal cord is part of the central nervous system. It is located in the spinal canal. It is a thick-walled tube with a narrow channel inside, somewhat flattened in the anteroposterior direction. It has a rather complex structure and ensures the transmission of nerve impulses from the brain to the peripheral structures of the nervous system, and also carries out its own reflex activity. Without the functioning of the spinal cord, normal breathing, heartbeat, digestion, urination, sexual activity, and any movements in the limbs are impossible. From this article you can learn about the structure of the spinal cord and the features of its functioning and physiology.

The spinal cord begins to develop in the 4th week intrauterine development. Usually a woman does not even suspect that she will have a child. Throughout pregnancy, differentiation of various elements occurs, and some parts of the spinal cord completely complete their formation after birth during the first two years of life.

What does the spinal cord look like externally?

The beginning of the spinal cord is conventionally determined at the level of the upper edge of I cervical vertebra and the foramen magnum of the skull. In this area, the spinal cord is gently rebuilt into the brain; there is no clear separation between them. At this point, the so-called pyramidal tracts cross: the conductors responsible for the movements of the limbs. The lower edge of the spinal cord corresponds to the upper edge of the II lumbar vertebra. Thus, the length of the spinal cord is less than the length of the spinal canal. It is this feature of the location of the spinal cord that makes it possible to perform a spinal puncture at the level of the III-IV lumbar vertebrae (it is impossible to damage the spinal cord during a lumbar puncture between the spinous processes of the III-IV lumbar vertebrae, since it is simply not there).

The dimensions of the human spinal cord are as follows: length approximately 40-45 cm, thickness - 1-1.5 cm, weight - about 30-35 g.

The spinal cord is divided into several sections according to its length:

• cervical;
• chest;
• lumbar;
• sacral;
• coccygeal

In the region of the cervical and lumbosacral levels, the spinal cord is thicker than in other regions, because clusters of nerve cells, providing movement of the arms and legs.

The last sacral segments, together with the coccygeal segment, are called the conus spinal cord due to their corresponding geometric shape. The cone passes into the terminal (final) filament. The thread no longer has nerve elements in its composition, but only connective tissue, and is covered with the membranes of the spinal cord. The terminal filum is fixed to the II coccygeal vertebra.

The entire length of the spinal cord is covered with 3 meninges. The first (inner) membrane of the spinal cord is called soft. It carries arterial and venous vessels that provide blood supply to the spinal cord. The next shell (middle) is the arachnoid (arachnoid). Between the inner and middle membranes there is a subarachnoid (subarachnoid) space containing cerebrospinal fluid (CSF). When performing a spinal puncture, the needle must enter exactly this space so that the cerebrospinal fluid can be taken for analysis. The outer shell of the spinal cord is hard. The dura mater continues to the intervertebral foramina, accompanying the nerve roots.

Inside the spinal canal, the spinal cord is attached to the surface of the vertebrae by ligaments.

In the middle of the spinal cord along its entire length there is a narrow tube, the central canal. It also contains cerebrospinal fluid.

From all sides, depressions – fissures and grooves – protrude deep into the spinal cord. The largest of them are the anterior and posterior median fissures, which separate the two halves of the spinal cord (left and right). Each half has additional depressions (grooves). The grooves split the spinal cord into cords. The result is two anterior, two posterior and two lateral cords. This anatomical division has a functional basis - nerve fibers pass through different cords, carrying different information (about pain, about touch, about temperature sensations, about movements, etc.). Blood vessels penetrate into the grooves and crevices.

Segmental structure of the spinal cord - what is it?

How is the spinal cord connected to the organs? In the transverse direction, the spinal cord is divided into special sections, or segments. From each segment there are roots, a pair of anterior ones and a pair of posterior ones, which communicate the nervous system with other organs. The roots emerge from the spinal canal and form nerves that are directed to various structures of the body. The anterior roots transmit information primarily about movements (stimulate muscle contraction), therefore they are called motor roots. The dorsal roots carry information from receptors to the spinal cord, that is, they send information about sensations, which is why they are called sensitive.

The number of segments is the same for all people: 8 cervical segments, 12 thoracic, 5 lumbar, 5 sacral and 1-3 coccygeal (usually 1). The roots from each segment rush into the intervertebral foramen. Since the length of the spinal cord is shorter than the length of the spinal canal, the roots change their direction. In the cervical region they are directed horizontally, in the thoracic region - obliquely, in the lumbar and sacral regions- almost vertically down. Due to the difference in the length of the spinal cord and spine, the distance from the exit of the roots from the spinal cord to the intervertebral foramen also changes: in the cervical region the roots are the shortest, and in the lumbosacral region they are the longest. The roots of the four lower lumbar, five sacral and coccygeal segments form the so-called cauda equina. It is this that is located in the spinal canal below the second lumbar vertebra, and not the spinal cord itself.

Each segment of the spinal cord is assigned a strictly defined zone of innervation on the periphery. This zone includes an area of ​​skin, certain muscles, bones, part internal organs. These zones are almost the same for all people. This structural feature of the spinal cord allows one to diagnose the location of the pathological process in the disease. For example, knowing that the sensitivity of the skin in the navel area is regulated by the 10th thoracic segment, if the sensation of touching the skin below this area is lost, we can assume that pathological process in the spinal cord located below the 10th thoracic segment. This principle works only taking into account the comparison of zones of innervation of all structures (skin, muscles, and internal organs).

If you cut the spinal cord in a transverse direction, it will not look the same in color. On the cut you can see two colors: gray and white. Gray color is the location of the cell bodies of neurons, and White color- these are the peripheral and central processes of neurons (nerve fibers). In total, there are more than 13 million nerve cells in the spinal cord.

Neuron cell bodies gray so arranged that they have a bizarre butterfly shape. This butterfly has clearly visible convexities - the front horns (massive, thick) and the rear horns (much thinner and smaller). Some segments also have lateral horns. The area of ​​the anterior horns contains the bodies of neurons responsible for movement, the area of ​​the posterior horns contains neurons that receive sensory impulses, and the lateral horns contain neurons of the autonomic nervous system. In some parts of the spinal cord, the bodies of nerve cells responsible for the functions of individual organs are concentrated. The locations of these neurons have been studied and clearly defined. Thus, in the 8th cervical and 1st thoracic segments there are neurons responsible for the innervation of the pupil of the eye, in the 3rd - 4th cervical segments - for the innervation of the main respiratory muscle (diaphragm), in the 1st - 5th thoracic segments - for regulation of cardiac activity. Why do you need to know this? This is used in clinical diagnostics. For example, it is known that the lateral horns of the 2nd - 5th sacral segments of the spinal cord regulate the activity of the pelvic organs ( Bladder and rectum). If there is a pathological process in this area (hemorrhage, tumor, destruction due to injury, etc.), a person develops urinary and fecal incontinence.

The processes of neuron bodies form connections with each other, with in different parts spinal cord and brain tend upward and downward, respectively. These nerve fibers, which are white in color, constitute the white matter in cross section. They also form the cords. In the cords, the fibers are distributed in a special pattern. In the posterior cords there are conductors from the receptors of muscles and joints (articular-muscular feeling), from the skin (recognition of an object by touch with closed eyes, sensation of touch), that is, the information goes in an upward direction. In the lateral cords there pass fibers that carry information about touch, pain, temperature sensitivity to the brain, to the cerebellum about the position of the body in space, muscle tone (ascending conductors). In addition, the lateral cords also contain descending fibers that provide body movements programmed in the brain. In the anterior cords there are both descending (motor) and ascending (sensation of pressure on the skin, touch) pathways.

The fibers can be short, in which case they connect the segments of the spinal cord with each other, and long, in which case they communicate with the brain. In some places, the fibers may cross or simply move to the opposite side. The crossing of different conductors occurs at different levels (for example, the fibers responsible for the feeling of pain and temperature sensitivity cross 2-3 segments above the level of entry into the spinal cord, and the fibers of the joint-muscular sense go uncrossed to the very upper parts of the spinal cord). The result of this is the following fact: in the left half of the spinal cord there are conductors from the right parts of the body. This does not apply to all nerve fibers, but is especially true for sensory processes. Studying the course of nerve fibers is also necessary to diagnose the location of the lesion in the disease.

Blood supply to the spinal cord

Nutrition of the spinal cord is provided blood vessels, coming from the vertebral arteries and from the aorta. The uppermost cervical segments receive blood from the vertebral artery system (as does part of the brain) through the so-called anterior and posterior spinal arteries.

Along the entire spinal cord, additional vessels carrying blood from the aorta, the radicular arteries, flow into the anterior and posterior spinal arteries. The latter also come in front and rear. Quantity similar vessels due to individual characteristics. Usually there are about 6-8 anterior radicular-spinal arteries, they are larger in diameter (the thickest ones are suitable for the cervical and lumbar enlargements). The inferior radicular-spinal artery (the largest) is called the artery of Adamkiewicz. Some people have an additional radicular-spinal artery coming from the sacral arteries, the Deproge-Gotteron artery. The blood supply zone of the anterior radicular-spinal arteries occupies the following structures: the anterior and lateral horns, the base of the lateral horn, the central sections of the anterior and lateral cords.

The posterior radicular-spinal arteries are an order of magnitude larger than the anterior ones - from 15 to 20. But they have a smaller diameter. The area of ​​their blood supply is the posterior third of the spinal cord in cross section (posterior cords, main part of the posterior horn, part of the lateral cords).

In the system of radicular-spinal arteries there are anastomoses, that is, places where vessels connect with each other. It plays an important role in the nutrition of the spinal cord. If a vessel stops functioning (for example, a blood clot has blocked the lumen), then blood flows through the anastomosis, and the neurons of the spinal cord continue to perform their functions.

The veins of the spinal cord accompany the arteries. The venous system of the spinal cord has extensive connections with the vertebral venous plexuses and veins of the skull. Blood from the spinal cord the whole system vessels flows into the superior and inferior vena cava. At the point where the veins of the spinal cord pass through the hard meninges There are valves that prevent blood from flowing in the opposite direction.

Functions of the spinal cord

Essentially, the spinal cord has only two functions:

• reflex;
• conductor.

Let's take a closer look at each of them.

Reflex function of the spinal cord

The reflex function of the spinal cord is the response of the nervous system to irritation. Have you touched something hot and involuntarily pulled your hand away? It's a reflex. Did something get in your throat and you started coughing? This is also a reflex. Many of our daily actions are based precisely on reflexes that are carried out thanks to the spinal cord.

So, a reflex is a response. How is it reproduced?

To make it clearer, let's take as an example the reaction of withdrawing the hand in response to touching a hot object (1). The skin of the hand contains receptors (2) that perceive heat or cold. When a person touches something hot, an impulse (signaling “hot”) travels from the receptor along the peripheral nerve fiber (3) to the spinal cord. At the intervertebral foramen there is a spinal node in which the body of the neuron (4) is located, along the peripheral fiber of which the impulse arrived. Further along the central fiber from the neuron body (5), the impulse enters the posterior horns of the spinal cord, where it “switches” to another neuron (6). The processes of this neuron are directed to the anterior horns (7). In the anterior horns, the impulse switches to motor neurons (8), responsible for the work of the arm muscles. The processes of motor neurons (9) leave the spinal cord, pass through the intervertebral foramen and, as part of the nerve, are directed to the muscles of the arm (10). The “hot” impulse causes the muscles to contract, and the hand withdraws from the hot object. Thus, a reflex ring (arc) was formed, which provided a response to the stimulus. In this case, the brain did not participate at all in the process. The man pulled his hand back without thinking about it.

Each reflex arc has obligatory links: an afferent link (a receptor neuron with peripheral and central processes), an intercalary link (a neuron connecting the afferent link with an executing neuron) and an efferent link (a neuron that transmits an impulse to the direct executor - an organ, a muscle).

The reflex function of the spinal cord is built on the basis of such an arc. Reflexes are innate (which can be determined from birth) and acquired (formed during life during learning), they are closed at different levels. For example, the knee reflex closes at the level of the 3rd-4th lumbar segments. By checking it, the doctor makes sure that all elements of the reflex arc are intact, including segments of the spinal cord.

It is important for the doctor to check the reflex function of the spinal cord. This is done at every neurological examination. Most often, superficial reflexes are tested, which are caused by touch, line irritation, puncture of the skin or mucous membranes, and deep reflexes, which are caused by the blow of a neurological hammer. Surface reflexes carried out by the spinal cord include abdominal reflexes (stroke irritation of the skin of the abdomen normally causes contraction of the abdominal muscles on the same side), plantar reflex (stroke irritation of the skin of the outer edge of the sole in the direction from the heel to the toes normally causes flexion of the toes) . Deep reflexes include flexion-elbow, carporadial, extension-elbow, knee, and Achilles.

Conducting function of the spinal cord

The conductor function of the spinal cord is to transmit impulses from the periphery (from the skin, mucous membranes, internal organs) to the center (brain) and vice versa. The conductors of the spinal cord, which make up its white matter, transmit information in the ascending and descending directions. An impulse about an external influence is sent to the brain, and a certain sensation is formed in a person (for example, you are petting a cat, and you have a feeling of something soft and smooth in your hand). This is impossible without the spinal cord. Evidence of this comes from cases of spinal cord injuries, where connections between the brain and spinal cord are disrupted (for example, spinal cord rupture). Such people lose sensitivity; touch does not create sensations in them.

The brain receives impulses not only about touch, but also about the position of the body in space, the state of muscle tension, pain, and so on.

Descending impulses allow the brain to “guide” the body. Thus, what a person intends is carried out with the help of the spinal cord. Did you want to catch up with the leaving bus? The plan is immediately realized - the the right muscles(and you don’t think about which muscles need to be contracted and which ones to relax). This is done by the spinal cord.

Of course, the implementation of motor acts or the formation of sensations require complex and well-coordinated activity of all structures of the spinal cord. In fact, you need to use thousands of neurons to get results.

The spinal cord is a very important anatomical structure. His normal functioning provides all human life activity. It serves as an intermediate link between the brain and various parts body, transmitting information in the form of impulses in both directions. Knowledge of the structure and functioning of the spinal cord is necessary for diagnosing diseases of the nervous system.

Video on the topic “Structure and functions of the spinal cord”

Our body is a very complex, but at the same time very important system in which all parts, organs and even cells are connected. To understand how the human body works, you should know the anatomy and physiology of all organs. Here we will try to find out what the nervous system consists of and the functions of the spinal cord.

What is spinal tissue?

Anatomy is the science of the structure of the human body; it is the foundation of all medicine. Without knowledge of such a subject as anatomy, not a single physician can work, although any person needs this knowledge. As you know, the nervous system is a very delicate component of the human body, one of the components of which is the spinal cord.

The influence of the human nervous system cannot be overestimated. That's why you should know the anatomy and structure of the brain and how it affects a person's life.

A person is a part that begins in the first weeks of fetal development and ends after birth. To diagnose and treat diseases, you should know the structure of the organ, the place where it is located, the function it performs, its effect on the function of other organs, and abnormalities in operation. We know that the nervous system has an influence on all human organs.

The spinal cord (medulla spinalis) is an organ of the human central nervous system, located in a canal that is protected by three membranes - soft, arachnoid and dura mater.

Consists of parts:

• brain canal;
• the spinal cord has a cavity filled cerebrospinal fluid;
• spinal nerves;
• several types of vessels (arteries of different sizes).

It is located in the spinal canal of the spine and has a tube-like shape with a lumen inside. Its task is the work of the peripheral nervous system, as well as the transmission of impulses to all organs. The nervous system affects:

Structure of the spinal cord

Running your hand along the spine, you feel that it is divided into segments and follows all the bends of the pillars. It is in the spinal canal that the brain is located. In the anatomy manual, the length of this section of the nervous system is indicated somewhere around 45 cm, thickness - no more than 1.5 cm, weight - up to 35 g, but this figure may vary for each person.

The origin can be determined from the surface of the first cervical vertebra, which borders the cymagnular foramen. It ends at the level of the edge of the second vertebra; you can see that it is somewhat shorter than the spine itself. Thanks to this, in medical practice they use a puncture, which is performed at the level of the 3-4 vertebrae of the lumbar region, and without the risk of damage to the brain itself. This manipulation is done for diagnostic purposes, when medications are administered or spinal contents are taken for research.

The spinal cord passes into the body medulla oblongata at the spinal nerve (first, pay attention). In structure, this is the space between the back of the head and the first vertebra of the neck. It is believed that it is a continuation of the oblongata.

It is worth noting that the nervous system is made up of gray and white matter. The length of the medulla oblongata is about 2.5 cm. The anatomy and physiology of the medulla oblongata is more complex than the spinal cord. On the ventral side there is a limitation of the medulla oblongata by the decussation of the pyramids.

The shape of the brain in this section resembles a cone. The influence of the medulla oblongata on the perception of auditory and vestibular reflexes is very great. Also, the significance of the medulla oblongata is that the ascending and descending tracts of the spinal cord pass through it. The role of the medulla oblongata is significant, since it is responsible for the postural maintenance reflex.

We can say that the significance of the medulla oblongata lies in the connection of the spinal and head parts into one whole. The nervous system is generally one system that is connected to all organs.

At the level of the medulla oblongata, irritations occur, only then the impulse is transmitted to the structures of the subcortex.

In the lower section it passes into the filum terminale, which is a reduced part of the dorsal section. The terminal filament, together with the hard shell, penetrates the sacral canal and is fixed at its end. There are two types of terminal filament - external and internal. The outer part of the thread is the end fused with the hard shell, and the inner part is located in the cavity of the hard shell and is not fused with it.

There are four surfaces of the spinal cord.

• somewhat flattened anterior;
• slightly protruding rear;
• two almost round lateral ones, which go into the front and back.

The spinal cord, like the spine, does not have the same thickness along its entire length. They achieve a larger diameter in the neck and sacrum (places of stress on the nerve endings).

Internal structure

The basis of the structure is the spinal membranes. There are three shells in total:

The spinal membranes play a significant role in the body. They are unique in their structure. It should be noted that all shells have their own structure and function.

Soft shells- this is the first defense of the brain, consists of loose tissue that penetrates and envelops all cracks and grooves. The tissue contains blood vessels that supply the brain.

Arachnoid membranes - middle part protection of the human spinal cord, separated from the soft part by cerebrospinal fluid. The space between the membranes is filled with blood vessels and spinal nerves (“cauda equina”). Connects to the hard defense of the brain.

Hard shells are a compound consisting of tissue with outer and inner surfaces. It is separated from the walls by the epidural space and the venous plexus. In the intervertebral space it fuses with the periosteum and forms spaces (vaginas) where the bundle of spinal nerves passes. The membranes are very important for maintaining the conductive function of the organ. The membranes of the spinal cord each perform their own role.

As mentioned, they consist of gray and white matter. If you look at a section of the spinal cord, you can see that the gray matter is located in the center, and the white matter is located at the periphery.

So, having understood, we should focus on the blood supply to this part of the body, which affects the functioning of every cell in our body, and also determine which vessels feed the tissue of the spine.

Blood supply to the spinal cord

In order for each cell to grow and reproduce, a sufficient amount of substances and oxygen is necessary. This function is performed circulatory system human body.

The blood supply to the brain is provided by different types of arteries.

• vertebral (comes from the subclavian artery);
• deep cervical (costocervical trunk);
• posterior intercostal, lumbar and lateral sacral arteries.

Three vessels are adjacent to the spinal cord - the anterior and two posterior spinal arteries. These arteries play a role in blood supply. Many arteries, about 60 pairs, which arise from the intervertebral foramina, supply blood only to the roots and parts of the membranes; unpaired arteries supply the remaining segments. The blood flow is carried out in directions and consists not only of the artery, but also of the anastomoses between them. Thus, there are 3 pools:

• superior cervical-dorsal;
• average intermediate;
• lower lumbar.

Each element of the spine has a different need for blood supply. Thus, arteries supply blood to spinal regions such as the neck and lumbar region. The thoracic and coccygeal muscles are supplied with blood much worse; this is not a pathology. However, the supply of blood to the artery is the key to human health.

Innervation

Before talking about the innervation of this part of the nervous system, it is worth recalling that the following segments are distinguished:

Spinal roots emerge from each segment, in 2 pairs: anterior and posterior. They are the ones who influence and determine the functioning of all organs and systems. The anterior spinal roots are called motor roots because they transmit information about body movement. The posterior spinal roots transmit sensations.

Considering that the spine is longer than the spinal cord itself, the roots can change their direction:

• in the cervical segment – ​​horizontally;
• in the chest - obliquely;
• in the lumbar and sacral – vertically.

Each segment is assigned a peripheral part. For example, the peri-umbilical zone is innervated by the roots of the 10th thoracic segment; accordingly, if sensitivity in this area is impaired, the doctor will suspect osteochondrosis of the breast. The nervous system in this area is responsible for reflexes and impulses. Therefore, the nervous system and the peripheral system are interconnected.

Diseases

Without a doubt, we all now lead a sedentary lifestyle, which negatively affects the condition of not only the brain, but also the spine. Even more destructive to the spinal cord, in addition to sports and childbirth (unfortunately, tension in the lower part of our body leads to disruption of brain function), are diseases of the cardiovascular system.

Another of the most common ailments of nerve endings is osteochondrosis. There are many reasons for its occurrence in the body: excess weight, poor physical fitness, spinal injuries (old and not so old), physical exercise, etc. The form of this disease is radiculitis.

Intervertebral hernia (pseudoradiculitis) is a disease in which discs are displaced and the nerve endings are pinched, after which, during the treatment of “radiculitis,” ossification of the nerves occurs. After, frozen in a different position, the nerve endings begin to send pain signals to the places where the hernia is located: the lower back, chest, neck. What is it like to live with spinal problems, you can ask any aged person, and he will say that health should be protected from youth.

Of course, it's far from here full list diseases of the nerve endings of the spinal cord, but the most common are these diseases.

Disease Prevention

Well, prevention is the cure you can imagine. The procedures are as follows:

Limit the amount of salt as a seasoning. Salt is an ingredient that is found in any food product and remains in the body, resulting in excess weight. You should eat fruits and vegetables, fish, light meat (such as chicken). How better food- the more likely it is that there will be no excess weight, which puts pressure on organs and nerve endings.

Physical education classes. Doctors advise consulting with a specialist before starting to exercise. This will not be a hindrance and will help you determine the load that you can withstand.

Important: the nervous system loves to be treated with care. Therefore, in order for the nervous system not to be upset by illnesses, you should take care of it and avoid stress and injury.

The spinal cord is a section of the central nervous system of the spine, which is a cord 45 cm long and 1 cm wide.

Structure of the spinal cord

The spinal cord is located in the spinal canal. Behind and in front there are two grooves, thanks to which the brain is divided into right and left halves. It is covered with three membranes: vascular, arachnoid and hard. The space between the choroid and arachnoid membranes is filled with cerebrospinal fluid.

In the center of the spinal cord you can see gray matter, shaped like a butterfly when cut through. Gray matter consists of motor and interneurons. Outer layer The brain is a white matter of axons collected in descending and ascending pathways.

There are two types of horns in the gray matter: anterior, which contains motor neurons, and posterior, where interneurons are located.

The structure of the spinal cord has 31 segments. From each of them extend the anterior and posterior roots, which, merging, form the spinal nerve. When leaving the brain, the nerves immediately split into roots - posterior and anterior. The dorsal roots are formed with the help of axons of afferent neurons and they are directed into the dorsal horns of the gray matter. At this point they form synapses with efferent neurons, whose axons form the anterior roots of the spinal nerves.

The dorsal roots contain the spinal nodes, which contain sensory nerve cells.

The spinal canal runs through the center of the spinal cord. To the muscles of the head, lungs, heart, organs chest cavity And upper limbs the nerves arise from segments of the upper thoracic and cervical parts of the brain. Organs abdominal cavity and the muscles of the trunk are controlled by the segments of the lumbar and chest parts. Muscles of the lower abdominal cavity and muscles lower limbs control the sacral and lower lumbar segments of the brain.

Functions of the spinal cord

There are two main functions of the spinal cord:

• Conductor;
• Reflex.

The conductor function is that nerve impulses move along the ascending pathways of the brain to the brain, and commands are sent through the descending pathways from the brain to the working organs.

The reflex function of the spinal cord is that it allows you to perform the simplest reflexes (knee reflex, withdrawal of the hand, flexion and extension of the upper and lower extremities, etc.).

Only simple motor reflexes are carried out under the control of the spinal cord. All other movements, such as walking, running, etc., require the participation of the brain.

Spinal cord pathologies

Based on the causes of spinal cord pathologies, three groups of spinal cord diseases can be distinguished:

• Developmental defects – postnatal or congenital abnormalities in the structure of the brain;
• Diseases caused by tumors, neuroinfections, spinal circulatory disorders, hereditary diseases nervous system;
• Spinal cord injuries, which include bruises and fractures, compression, concussions, dislocations and hemorrhages. They can appear either independently or in combination with other factors.

Any diseases of the spinal cord are very serious consequences. A special type of disease includes spinal cord injuries, which, according to statistics, can be divided into three groups:

• Car accidents are the most common cause of spinal cord injury. Driving motorcycles is especially dangerous because there is no backrest to protect the spine.
• A fall from a height can be either accidental or intentional. In any case, the risk of spinal cord damage is quite high. Often athletes, fans of extreme sports and jumping from heights get injured in this way.
• Everyday and extraordinary injuries. They often occur as a result of going down and falling in the wrong place, falling down the stairs or when there is ice. This group also includes knife and bullet wounds and many other cases.

With spinal cord injuries, the conduction function is primarily disrupted, which leads to very disastrous consequences. For example, damage to the brain in the cervical region leads to the fact that brain functions are preserved, but they lose connections with most organs and muscles of the body, which leads to paralysis of the body. The same disorders occur when damaged peripheral nerves. If the sensory nerves are damaged, then sensitivity is impaired in certain areas of the body, and the damage motor nerves interferes with the movement of certain muscles.

Most nerves are of a mixed nature, and their damage causes both the inability to move and loss of sensation.

Spinal cord puncture

A spinal puncture involves inserting a special needle into the subarachnoid space. A puncture of the spinal cord is performed in special laboratories, where the patency of this organ is determined and the pressure of the cerebrospinal fluid is measured. The puncture is carried out both therapeutically and diagnostic purposes. It allows you to timely diagnose the presence of hemorrhage and its intensity, find inflammatory processes in the meninges, determine the nature of the stroke, determine changes in the nature of the cerebrospinal fluid, signaling diseases of the central nervous system.

Often a puncture is performed to administer radiopaque and medicinal fluids.

IN medicinal purposes puncture is performed to extract blood or purulent fluid, as well as for the administration of antibiotics and antiseptics.

Indications for spinal cord puncture:

• Meningoencephalitis;
• Unexpected hemorrhages in the subarachnoid space due to rupture of an aneurysm;
• Cysticercosis;
• Myelitis;
• Meningitis;
• Neurosyphilis;
• Traumatic brain injury;
• Liquororrhea;
• Echinococcosis.

Sometimes during brain surgery, spinal cord puncture is used to reduce parameters intracranial pressure, as well as to facilitate access to malignant neoplasms.

SPINAL CORD AND SPINAL NERVES

8.1, GENERAL PROVISIONS

In previous chapters (see Chapters 2, 3, 4) the general principles of the structure of the spinal cord and spinal nerves, as well as the manifestations of sensory and motor pathology when they are damaged, were discussed. This chapter focuses mainly on specific issues of morphology, function and some forms of damage to the spinal cord and spinal nerves.

8.2. SPINAL CORD

The spinal cord is a part of the central nervous system that has retained distinct features of a segmental structure, primarily characteristic of its gray matter. The spinal cord has numerous mutual connections with the brain. Both of these parts of the central nervous system normally function as a single whole. In mammals, in particular in humans, the segmental activity of the spinal cord is constantly influenced by efferent nerve impulses emanating from various structures of the brain. This influence, depending on many circumstances, can be activating, facilitating or inhibiting.

8.2.1. Gray matter of the spinal cord

Gray matter of the spinal cord make up mainly bodies of nerve and glial cells. The non-identity of their number at different levels of the spinal cord causes variability in the volume and configuration of gray matter. In the cervical region of the spinal cord, the anterior horns are wide, thoracic region The gray matter on a cross section becomes similar to the letter “H”; in the lumbosacral region, the size of both the anterior and posterior horns is especially significant. The gray matter of the spinal cord is fragmented into segments. A segment is a fragment of the spinal cord, anatomically and functionally connected to one pair of spinal nerves. The anterior, posterior and lateral horns can be considered as fragments of vertically located columns - anterior, posterior and lateral, separated from each other by the spinal cord cords consisting of white matter.

The following circumstance plays an important role in the implementation of reflex activity of the spinal cord: almost all axons of the cells of the spinal ganglia entering the spinal cord as part of the dorsal roots have branches - collaterals. Collaterals of sensory fibers contact directly with peripheral motor neurons, located in the anterior horns, or Withinterneurons, the axons of which also reach the same motor cells. Collaterals of axons extending from the cells of the intervertebral ganglia not only reach the corresponding peripheral motor neurons located in the anterior horns of the nearest segments of the spinal cord, but also penetrate into its neighboring segments, forming the so-called spinal-spinal intersegmental connections, providing irradiation of excitation that came to the spinal cord after irritation of the receptors of deep and superficial sensitivity located on the periphery. This explains a common reflex motor reaction in response to local irritation. This kind of phenomenon is especially typical when the inhibitory influence of pyramidal and extrapyramidal structures on peripheral motor neurons that are part of the segmental apparatus of the spinal cord decreases.

Nerve cells, The components of the gray matter of the spinal cord can be divided into the following groups according to their function:

1. Sensitive cells(T cells of the dorsal horn of the spinal cord) are the bodies of the second neurons of the sensory pathways. Most of axonssecond neurons sensitive pathways within the white commissure goes overon the opposite side where it participates in the formation of the lateral cords of the spinal cord, forming ascending cords in them spinothalamic tracts AndGovers' anterior spinocerebellar tract. Axons of second neurons, have not crossed over to the opposite side, directed to the homolateral lateral cord Andform V him Flexig's posterior spinocerebellar tract.

2. Association (intercalated) cells, related to the spinal cord's own apparatus, participate in the formation of its segments. Their axons end in the gray matter of the same or closely located spinal segments.

3. Vegetative cells located in the lateral horns of the spinal cord at the level of C8-L2 segments (sympathetic cells) And in segments S3- - S5 (parasympathetic cells). Their axons leave the spinal cord as part of the anterior roots.

4. Motor cells (peripheral motor neurons) constitute the anterior horns of the spinal cord. Converges to them a large number of nerve impulses coming from various parts of the brain along numerous descending pyramidal and extrapyramidal pathways. In addition, nerve impulses come to them along the collaterals of the axons of pseudounipolar cells, the bodies of which are located in the spinal ganglia, as well as through the collaterals of the axons of sensory cells of the dorsal horns and associative neurons of the same or other segments of the spinal cord, carrying information mainly from deep sensitivity receptors, and along the axons located in the anterior horns of the spinal cord, Renshaw cells, which send impulses that reduce the level of excitation of alpha motor neurons and, therefore, reduce the tension of the striated muscles.

The cells of the anterior horns of the spinal cord serve as a site for the integration of excitatory and inhibitory impulses coming from various sources. The addition of the excitatory and inhibitory biopotentials arriving at the motor neuron determines its total bioelectric charge and, in connection with this, the features of the functional state.

Among the peripheral motor neurons located in the anterior horns of the spinal cord, two types of cells are distinguished: a) alpha motor neurons - large motor cells, the axons of which have a thick myelin sheath (A-alpha fibers) and end in the muscle end plates; they provide the degree of tension of the extrafusal muscle fibers that make up the bulk of the striated muscles; b) gamma motor neurons - small motor cells, the axons of which have a thin myelin sheath (A-gamma fibers) and, therefore, a lower speed of nerve impulses. Gamma motor neurons make up approximately 30% of all cells in the anterior horn of the spinal cord; their axons are directed to the intrafusal muscle fibers that are part of the proprio receptors - muscle spindles.

Muscle spindle consists of several thin intrafusal muscle fibers enclosed in a fusiform connective tissue capsule. The axons of gamma motor neurons end on the intrafusal fibers, affecting the degree of their tension. Stretching or contraction of intrafusal fibers leads to changes in the shape of the muscle spindle and irritation of the spiral fiber surrounding the equator of the spindle. In this fiber, which is the beginning of the dendrite of a pseudounipolar cell, a nerve impulse arises, which is directed to the body of this cell, located in the spinal ganglion, and then along the axon of the same cell to the corresponding segment of the spinal cord. The terminal branches of this axon directly or through interneurons reach the alpha motor neuron, exerting an excitatory or inhibitory effect on it.

Thus, with the participation of gamma cells and their fibers, gamma loop, ensuring the maintenance of muscle tone and a fixed position of a certain part of the body or contraction of the corresponding muscles. In addition, the gamma loop ensures the transformation of the reflex arc into a reflex ring and takes part in the formation, in particular, of tendon or myotatic reflexes.

Motor neurons in the anterior horns of the spinal cord form groups, each of which innervates muscles that share a common function. Along the length of the spinal cord there are anterior internal groups of cells of the anterior horns, which provide the function of muscles that influence the position of the spinal column, and anterior external groups of peripheral motor neurons, on which the function of the remaining muscles of the neck and torso depends. In the segments of the spinal cord that provide innervation to the limbs, there are additional groups of cells located mainly behind and outside the already mentioned cellular associations. These additional groups of cells are the main cause of cervical (at the level of C5-Th2 segments) and lumbar (at the level of L2-S2 segments) thickenings of the spinal cord. They provide mainly innervation to the muscles of the upper and lower extremities.

Motor unit The neuromotor apparatus consists of a neuron, its axon and the group of muscle fibers innervated by it. The sum of peripheral motor neurons participating in the innervation of one muscle is known as its motor pool, in this case, the bodies of motor neurons of one motor pool can be located in several adjacent segments of the spinal cord. The possibility of damage to part of the motor units that are part of the muscle pool is the cause of partial damage to the muscle innervated by it, as happens, for example, with epidemic poliomyelitis. Widespread damage to peripheral motor neurons is characteristic of spinal amyotrophies, which are hereditary forms of neuromuscular pathology.

Among other diseases in which the gray matter in the spinal cord is selectively affected, syringomyelia should be noted. Syringomyelia is characterized by expansion of the usually reduced central canal of the spinal cord and the formation of gliosis in its segments, while the dorsal horns are more often affected, and then a dissociated type of sensitivity disorder occurs in the corresponding dermatomes. If degenerative changes also extend to the anterior and lateral horns, manifestations are possible in the metameres of the body, which are the same as the affected segments of the spinal cord. peripheral paresis muscles and vegetative-trophic disorders.

In cases of hematomyelia (bleeding in the spinal cord), usually resulting from spinal cord injury, the symptoms are similar to syringomyelitic syndrome. The lesion in traumatic hemorrhage in the spinal cord is predominantly of the gray matter due to the peculiarities of its blood supply.

Gray matter is also the site of predominant formation of intramedullary tumors growing from its glial elements. At the onset of the tumor, they may manifest themselves as symptoms of damage to certain segments of the spinal cord, but subsequently become involved in the process medial sections adjacent cords of the spinal cord. At this stage of intramedullary tumor growth, conduction-type sensory disturbances appear slightly below the level of its localization, which subsequently gradually descend downwards. Over time, at the level of the intramedullary tumor, a clinical picture of damage to the entire diameter of the spinal cord may develop.

Signs of combined damage to peripheral motor neurons and corticospinal pathways are characteristic of amyotrophic lateral sclerosis (ALS syndrome). In the clinical picture, various combinations of manifestations of peripheral and central paresis or paralysis arise. In such cases, as everything dies more peripheral motor neurons, the symptoms of already developed central paralysis are replaced by manifestations of peripheral paralysis, which over time increasingly predominate in the clinical picture of the disease.

8.2.2. White matter of the spinal cord

White matter forms cords located along the periphery of the spinal cord, consisting of ascending and descending pathways, most of which have already been discussed in previous chapters (see Chapters 3, 4). Now you can supplement and generalize the information presented there.

The nerve fibers present in the spinal cord can be differentiated into endogenous, which are processes of the spinal cord’s own cells, and exogenous - consisting of processes of nerve cells that have penetrated into the spinal cord, the bodies of which are located in the spinal ganglia or are part of the structures of the brain.

Endogenous fibers can be short or long. The shorter the fibers, the closer to the gray matter of the spinal cord they are located. Short endogenous fibers form spinospinal connections between the segments of the spinal cord itself (their own bundles of the spinal cord - fasciculi proprii). From long endogenous fibers, which are the axons of second sensory neurons, the bodies of which are located in the dorsal horns of the spinal cord segments, afferent pathways are formed that conduct pain and temperature sensitivity impulses going to the thalamus, and impulses going to the cerebellum (spinothalamic and spinocerebellar tracts).

Exogenous fibers of the spinal cord are axons of cells located outside of it. They can be afferent and efferent. Afferent exogenous fibers make up thin and wedge-shaped bundles that form the posterior funiculi. Among the efferent pathways consisting of exogenous fibers, the lateral and anterior corticospinal tracts should be noted. Exogenous fibers also consist of the extrapyramidal system of the red nucleus-spinal cord, vestibule-spinal cord, olivo-spinal cord, tectal-spinal cord, vestibular-spinal cord, reticulospinal cord pathways.

In the spinal cord, the most important pathways are distributed as follows (Fig. 8.1):

Posterior funiculi(funiculus posterior seu dorsalis) consist of ascending pathways conducting impulses of proprioceptive sensitivity. At the bottom of the spinal cord, the posterior cord is thin bun Naked(fasciculus gracilis). Starting from the mid-thoracic part of the spinal cord and above, lateral to the thin fasciculus, a wedge-shaped bundle of Burdach(fasciculus cuneatus). In the cervical spinal cord, both of these bundles are well defined and separated by a glial septum.

Damage to the posterior cord of the spinal cord leads to impaired proprioception and a possible decrease in tactile sensitivity below the level of the spinal cord lesion. A manifestation of this form of pathology is a violation of reverse afferentation in the corresponding part of the body due to the lack of proper information sent to the brain about the position of body parts in space. As a result, sensory ataxia and afferent paresis occur, while muscle hypotonia and tendon hyporeflexia or areflexia are also characteristic. This form of pathology is characteristic of tabes dorsalis, funicular myelosis, and is part of the symptom complexes characteristic of various forms of spinocerebellar ataxia, in particular Friedreich's ataxia.

The lateral cords (funiculus lateralis) consist of ascending and descending tracts. The dorsolateral section of the lateral funiculus occupies the posterior spinocerebellar tract of Flexig (tractus spinocerebellaris dorsalis). In the ventrolateral section there is the anterior spinocerebellar tract of Govers (tractus spinocerebellaris ventralis). Medial to Govers's path is the path of surface sensitivity impulses - the lateral spinothalamic tract (tractus spinothalamicus lateralis), behind it the red-spinal tract (tractus rubrospinalis), between it and the dorsal horn - the lateral corticospinal (pyramidal) tract (tractus corticospinalis lateralis) . In addition, the spinal reticular tract, tectal spinal tract, and olivospinal cord pass through the lateral cord, and autonomic fibers are scattered near the gray matter.

Rice. 8.1. Pathways on a transverse section of the upper thoracic spinal cord. 1 - posterior median septum; 2 - thin beam; 3 - wedge-shaped bundle; 4 - posterior horn; 5 - spinocerebellar tract, 6 - central channel, 7 - side horn; 8 - lateral spinothalamic tract; 9 - anterior spinocerebellar tract; 10 - anterior spinothalamic tract; 11 - front horn; 12 - anterior median fissure; 13 - olivospinal tract; 14 - anterior corticospinal (pyramidal) tract; 15 - anterior reticular-spinal tract; 16 - vestibulospinal tract; 17 - reticular-spinal tract; 18 - anterior white commissure; 19 - gray commissure; 20 - red nucleus-spinal tract; 21 - lateral corticospinal (pyramidal) tract; 22 - posterior white commissure.

Since in the lateral cord the corticospinal tract is located dorsal to the lateral spinothalamic tract, damage to the posterior segment of the spinal cord can lead to a disorder of deep sensitivity in combination with a pyramidal disorder below the level of localization of the pathological focus while maintaining superficial sensitivity (Roussy-Lhermitte-Schelvin syndrome).

Selective damage to the pyramidal tracts of the lateral cords of the spinal cord is possible, in particular, with familial spastic paraplegia, or Strumpel's disease, in which, by the way, due to the heterogeneity of the fibers that make up the pyramidal tract, a splitting of the pyramidal syndrome is characteristic, which is manifested by lower spastic paraparesis with a predominance of spastic muscle tension over a decrease in their strength.

Anterior cords(funiculus anterior seu ventralis) consist mainly of efferent fibers. Adjacent to the median fissure is the tectospinal tract (tractus tectospinalis), which belongs to the system of descending extrapyramidal tracts. More lateral are the anterior (uncrossed) corticospinal (pyramidal) tract (tractus corticospinalis anterior), vestibulospinal tract (tractus vestibulospinalis), anterior reticular spinal tract (tractus reticulospinalis anterior) and afferent anterior spinothalamic tract (tractus spinothalamicus anterior) . Behind them passes the medial longitudinal fasciculus (fasciculis longitudinalis medialis), carrying impulses from a number of cellular formations of the trunk tire.

At development of ischemia in the anterior spinal artery basin (Preobrazhensky syndrome) blood circulation in the anterior 2/3 of the spinal cord is impaired. At the level of the ischemic zone, flaccid muscle paralysis develops, below this level - spastic paralysis. Disorders of pain and temperature sensitivity of the conduction type and dysfunction of the pelvic organs are also characteristic. Proprioceptive and tactile sensitivity is preserved. This syndrome was described in 1904 by MA. Preobrazhensky (1864-1913).

8.3- SPINAL DIVISION OF THE PERIPHERAL NERVOUS SYSTEM AND SIGNS OF ITS DAMAGE

As already noted (see Chapter 2), the spinal part of the peripheral nervous system consists of the anterior and posterior spinal roots, spinal nerves, ganglia, nerve plexuses and peripheral nerves.

8.3.1. Some general issues clinical manifestations of damage to the peripheral nervous system

Syndromes of damage to the peripheral nervous system consist of peripheral paresis or paralysis and disorders of superficial and deep sensitivity of various nature and severity, and a significant frequency of pain syndrome should be noted. These phenomena are often accompanied by vegetative-trophic disorders in the corresponding part of the body - pallor, cyanosis, swelling, decreased skin temperature, impaired sweating, and degenerative processes.

When the spinal roots, ganglia or spinal nerves are damaged, the above disorders occur in the corresponding segments (metameres) of the body - their dermatomes, myotomes, sclerotomes. Selective involvement of the posterior or anterior spinal roots (radnculopathies) manifested by pain and sensory disturbances or peripheral paresis in the areas of their innervation. If the plexus is affected (plexopathy)- local pain is possible, radiating along the nerve trunks formed in this plexus, as well as motor, sensory and autonomic disorders in the innervation zone. In case of damage to the peripheral nerve trunk and its branches (neuropathy) characterized by flaccid paresis or paralysis of the muscles they innervate. In the area innervated by the affected nerve, there may be sensory disturbances and vegetative-trophic disorders that appear distal to the level of damage to the nerve trunk and in the area innervated by its branches extending below the location of the main pathological process. At the site of nerve damage, pain and soreness are possible, radiating along the course of the nerve, especially noticeable upon percussion of the affected area (Tinel's symptom).

Multiple symmetrical lesions of the distal parts of the peripheral nerves, characteristic of polyneuropathy, can cause combinations of movement disorders, sensitivity, as well as autonomic and trophic disorders in the distal parts of the extremities. However, with various forms of neuropathy or polyneuropathy, primary damage to the motor, sensory or autonomic structures of the peripheral nerves is possible. In such cases, we can talk about motor, sensory or autonomic neuropathy.

With peripheral nerve damage movement disorders may be less than expected in accordance with existing schematic representations. This is due to the fact that some muscles are innervated by two nerves. In such cases, interneural anastomoses may be significant, the nature of which is subject to large individual fluctuations. Anastomoses between nerves can, to some extent, help restore impaired motor functions.

When analyzing lesions of the peripheral nervous system, one must take into account the possibility of the development of compensatory mechanisms, sometimes masking existing muscle paresis. For example, dysfunction of the shoulder abductor deltoid muscle is partially compensated by the pectoral, subscapularis and trapezius muscles. The nature of the active movement can be assessed incorrectly due to the fact that it is performed not due to the contraction of the muscle under study, but as a result of the relaxation of its antagonists. Sometimes active movements are limited due to pain or due to damage to blood vessels, muscles, ligaments, bones and joints. Limitation of active and passive movements may be a consequence of formed contractures, in particular contractures of the antagonist muscles of the affected muscle. Multiple lesions of peripheral nerves, for example, with a nerve plexus injury, can also complicate topical diagnosis.

The diagnosis of peripheral paralysis or paresis, in addition to impaired movement, muscle hypotonia and a decrease or disappearance of certain reflexes, is facilitated by signs of muscle wasting that usually appear a few weeks after damage to a nerve or nerves, as well as a disturbance in the electrical excitability of the corresponding nerves and muscles that accompanies peripheral paresis or paralysis.

In the topical diagnosis of lesions of the peripheral nervous system, information obtained from a careful study of the state of sensitivity may be important. It must be borne in mind that each peripheral nerve corresponds to a certain zone of innervation on the skin, reflected in existing diagrams (Fig. 3.1). When diagnosing lesions of the peripheral nervous system, it should be taken into account that the zone of sensory impairment when individual nerves are damaged is usually smaller than its anatomical territory indicated on such diagrams. This is explained by the fact that the zones innervated by neighboring peripheral nerves, as well as sensitive spinal roots, partially overlap each other and, as a result, areas of the skin located on their periphery have additional innervation due to neighboring nerves. Therefore, the boundaries of the zone of impaired sensitivity at peripheral nerve damage is often limited to the so-called autonomous zone innervation, the size of which can vary within quite large limits due to the existing individual characteristics of innervation.

Impulses different types Sensitivity passes through various nerve fibers running as part of the peripheral nerve. In the case of nerve damage in the innervation zone, sensitivity of one type or another may be disrupted, leading to dissociation of sensory disorders. Impulses of pain and temperature sensitivity are transmitted through thin myelinated or unmyelinated fibers (A-gamma fibers or C-fibers). Impulses of proprioceptive and vibration sensitivity are carried along thick myelin fibers. Both thin and thick myelinated fibers are involved in the transmission of tactile sensitivity, while autonomic fibers are always thin and unmyelinated.

Determining the location and extent of damage to the peripheral nerve can be facilitated by the analysis of the sensations described by the patient that arise during palpation of the nerve trunks, their pain, as well as irradiation pain, which occurs during percussion possible location nerve damage (Tinel's sign).

The causes of damage to peripheral nerves are diverse: compression, ischemia, trauma, exogenous and endogenous intoxication, infectious and allergic lesions, metabolic disorders, in particular in connection with certain forms of hereditary pathology, enzymopathies and associated metabolic disorders.

8.3.2. Spinal nerve roots

Posterior roots (radices posteriores) spinal nerves are sensitive; they are composed of axons of pseudounipolar cells, the bodies of which are located in the spinal ganglia (ganglion spinalie). The axons of these first sensory neurons enter the spinal cord at the location of the posterior lateral sulcus.

Anterior roots (radices anteriores) mainly motor, they consist of axons of motor neurons that are part of the anterior horns of the corresponding segments of the spinal cord; in addition, they include the axons of vegetative Jacobson cells located in the lateral horns of the same spinal segments. The anterior roots exit the spinal cord through the anterior lateral sulcus.

Following from the spinal cord to the intervertebral foramina of the same name in the subarachnoid space, all the roots of the spinal nerves, except the cervical ones, descend down to one or another distance. It is small for the thoracic roots and more significant for the lumbar and sacral roots, which participate in the formation, together with the terminal filament, of the so-called horse tail.

The roots are covered with the pia mater, and at the junction of the anterior and posterior roots into the spinal nerve at the corresponding intervertebral foramen, the arachnoid membrane is also pulled towards it. As a result, a cerebrospinal fluid-filled area forms around the proximal portion of each spinal nerve. a funnel-shaped vagina, the narrow part directed towards the intervertebral foramen. The concentration of infectious agents in these funnels sometimes explains the significant frequency of damage to the spinal nerve roots during inflammation of the meninges (meningitis) and the development of the clinical picture of meningoradiculitis.

Damage to the anterior roots leads to peripheral paresis or paralysis muscle fibers, included in the corresponding myotomes. There may be a violation of the integrity of the corresponding reflex arcs and, in connection with this, the disappearance of certain reflexes. With multiple lesions of the anterior roots, for example, with acute demyelinating polyradiculoneuropathy (Guillain-Barré syndrome), widespread peripheral paralysis may develop, tendon and skin reflexes decrease and disappear.

Irritation of the dorsal roots due to one reason or another (discogenic radiculitis due to osteochondrosis of the spine, neuroma of the dorsal root, etc.) leads to pain that radiates to the metameres corresponding to the irritated roots. Nerve root pain may be provoked when checking the nerve root Neri's symptom, included in the group of tension symptoms. It is checked on a patient who lies on his back with his legs straightened. The examiner places his palm under the back of the patient's head and sharply bends his head, trying to ensure that the chin touches the chest. With pathology of the dorsal roots of the spinal nerves, the patient experiences pain in the area of ​​​​the projection of the affected roots.

When the roots are damaged, irritation of the nearby meninges and the appearance of changes in the cerebrospinal fluid are possible, usually of the type of protein-cell dissociation, as is observed, in particular, with Guillain-Barre syndrome. Destructive changes in the dorsal roots lead to a disorder of sensitivity in the dermatomes of the same name as these roots and can cause loss of reflexes, the arcs of which were interrupted.

8.3.3. Spinal nerves

The spinal nerves (Fig. 8.2), formed as a result of the union of the anterior and posterior roots, turn out to be mixed. They penetrate the dura mater, are short in length (about 1 cm) and are located in the intervertebral or sacral foramina. surrounding them connective tissue(epineurium) is connected to the periosteum, which makes their mobility very limited. Damage to the spinal nerves and their roots is often associated with degenerative phenomena in the spine (osteochondrosis) and the resulting posterior or posterolateral hernia between the vertebral disc, less often with infectious-allergic pathology, trauma, oncological diseases and, in particular, with internal vertebral extramedullary tumor, primarily neuroma, or spinal tumor. It manifests itself as signs of combined damage to the corresponding anterior and posterior roots of the spinal nerves, with possible pain, sensory disturbances, motor and autonomic disorders in the area of ​​the corresponding dermatomes, myotomes and sclerotomes.

Rice. 8.2. Transverse section of the spinal cord, formation of the spinal nerve and its branches. 1 - posterior horn; 2 - posterior cord; 3 - posterior median groove; 4 - posterior root; 5 - spinal node; 6 - trunk of the spinal nerve; 7 - posterior branch of the spinal nerve; 8 - internal branch of the posterior branch; 9 - external branch of the posterior branch; 10 - anterior branch; 11 - white connecting branches; 12 - shell branch; 13 - gray connecting branches; 14 - node of the sympathetic trunk; 15 - anterior median fissure; 16 - front horn; 17 - anterior cord; 18 - front spine, 19 - anterior gray commissure; 20 - central channel; 21 - lateral cord; 22 - postganglionic fibers.

Sensory fibers are indicated in blue, motor fibers in red, white connective fibers in green, and gray connective branches in purple.

Exists 31-32 pairs of spinal nerves. 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1-2 coccygeal.

The first cervical spinal nerve emerges between occipital bone and atlas, fifth sacral and coccygeal nerves - through the inferior opening of the sacral canal (hiatus sacralis).

Having emerged from the intervertebral or sacral foramen, the spinal nerves are divided into anterior, thicker, and posterior branches: mixed according to the composition of the nerve fibers entering them.

It immediately arises from the anterior branch of each spinal nerve shell(meningeal) branch (ramus meningeus), also known as Luschka's nerve, returning to the spinal canal and participating in the formation of the meningeal plexus (plexus meningeus), providing sensitive and autonomic innervation of the walls and vessels of the spinal canal, including the posterior longitudinal ligament, and the dura mater. In addition, each anterior branch is connected white connecting branch (ramus communicantes albt) with the nearest node of the border sympathetic trunk.

Further anterior branches of the spinal nerves are directed forward and pierce or go around the muscles attached to the transverse processes or to the ribs. The anterior branches of the thoracic spinal nerves form intercostal nerves. The anterior branches of the cervical, upper thoracic, lumbar and sacral spinal nerves are involved in the formation nerve plexuses.

There are cervical, brachial, lumbar, sacral, pudendal and coccygeal plexuses. From these plexuses come peripheral nerves, which provide innervation to most of the muscles and integumentary tissues of the human body. The nerve plexuses and the peripheral nerves emerging from them have their own anatomical and functional characteristics, and their damage leads to neurological symptoms that have a certain specificity.

Posterior branches of the spinal nerves relatively thin, bend around the articular processes of the vertebrae, are directed into the spaces between the transverse processes (on the sacrum they pass through the posterior sacral foramina) and, in turn, are divided into internal and external branches. The posterior branches of the spinal nerves innervate the muscles and skin in the paravertebral region throughout the spinal column.

The posterior branch of the first cervical (C1) spinal nerve is the suboccipital nerve (p. suboccipital), innervating the group of suboccipital muscles - the anterior rectus capitis muscle (i.e. rectus capitis anteriores), rectus capitis posterior major and minor muscles (vt. recti capitis posteriores major et minor), superior and inferior oblique muscles of the head (i.e. obliquus capiti superiores et inferiores), splenius capitis muscle (i.e. splenius capiti), longus capitis muscle (i.e. ongus capitis), when contracted, the head is extended and tilted back and towards the contracted muscles.

The posterior branch of the second cervical spinal nerve (C2) is directed between the atlas (C1) and axial (C2) vertebrae, goes around the lower edge of the inferior oblique muscle of the capitis and is divided into 3 branches: the ascending (ramus ascendens), downward (ramus descendens) And greater occipital nerve (nervus occipitalis major), which goes upward and, together with the occipital artery, pierces the tendon of the trapezius muscle near the external occipital protuberance and innervates the skin in the medial part of the occipital and parietal regions up to the level of the coronal suture. With damage to the second cervical spinal nerve (C2 or its posterior branch, which usually occurs with pathology of the upper cervical vertebrae (osteochondrosis, spondyloarthritis, discopathy, etc.), neuralgia of the greater occipital nerve may develop, manifested by intense, sometimes sharp, pain in the back of the head in the side of the pathological process. Attacks of pain can be provoked by movements of the head, in connection with this, patients usually fix the head, slightly tilting it towards the affected side to the side and back. With neuralgia of the greater occipital nerve, it is determined characteristic pain point, located on the border of the middle and inner thirds of the line connecting the mastoid process and the occipital protuberance. Sometimes there is hypo- or hyperesthesia of the skin of the back of the head, and one can observe a forced (due to pain) posture of the head - the head is motionless and slightly tilted back and towards the pathological process.

8.3.4. Cervical plexus and its nerves

Cervical plexus (plexus cervicalis) is formed by the interweaving of nerve fibers passing through the anterior branches of the I-IV cervical spinal nerves. The plexus is located in front of the corresponding cervical vertebrae on the anterior surface of the middle scalene muscle and the levator scapulae muscle, and is covered top part sternocleidomastoid muscle.

The first cervical spinal nerve (C) emerges from the spinal canal between the occipital bone and the atlas, located in the groove vertebral artery. Its anterior branch passes between the anterior lateral and lateral rectus capitis muscles (t. rectus capitis anterioris et lateralis). Damage to this nerve can lead to convulsive contraction of the inferior oblique capitis muscle, which causes the head to jerk in the direction of the lesion.

The remaining cervical nerves enter the anterior surface of the spine, passing between the anterior and posterior intertransverse muscles behind the vertebral artery. Two groups of branches depart from the cervical plexus - muscular and cutaneous.

Muscular branches of the cervical plexus: 1) short segmental branches to the deep muscles of the neck; 2) anastomosis with the descending branch of the hypoglossal nerve, participating in the formation of its loop; 3) branch to the sternocleidomastoid muscle; branch to the trapezius muscle and 4) the phrenic nerve containing sensory fibers.

Deep branches of the cervical plexus participate in the innervation of the muscles that provide movement in the cervical spine and the sublingual muscles. Together with XI (additional) cranial nerve they participate in the innervation of the sternocleidomastoid and trapezius muscles (t. sternocleidomastoi-deus et t. trapezius), as well as the longus colli muscle (n. longus colli), the contraction of which leads to flexion of the cervical spine, and with unilateral contraction - to flexion of the neck in the same direction.

Phrenic nerve (n. phrenicus) - continuation of the fibers of the anterior branches, mainly IV, partly III and V cervical spinal nerves - goes down, located between the subclavian artery and vein, penetrates the anterior mediastinum. On its way, the nerve of the diaphragm gives off sensory branches to the pleura, pericardium, and diaphragm, but the main part of it is motor and provides innervation to the diaphragm (abdominal barrier), recognized as the most important respiratory muscle.

When the phrenic nerve is damaged, it occurs paradoxical type of breathing: when inhaling, the epigastric region sinks, when exhaling, it protrudes - the opposite phenomenon to what is usually observed normally; In addition, coughing movements are difficult. Fluoroscopy reveals prolapse of the dome of the diaphragm and limitation of its mobility on the side of the affected nerve. Irritation of the nerve causes a spasm of the diaphragm, manifested by persistent hiccups, shortness of breath and pain in the chest, radiating to the shoulder girdle and shoulder joint area.

The following cutaneous nerves form in the cervical plexus.

Lesser occipital nerve (p. occipitalis minor). It is formed by the fibers of the anterior branches of the cervical (C2-C3) spinal nerves, emerges from under the posterior edge of the fudinocleidomastoid muscle at the level of its upper third and penetrates the skin of the outer part of the occipital region and the mastoid process. When the lesser occipital nerve is irritated, pain occurs in the innervation zone, often of a paroxysmal nature. (neuralgia of the lesser occipital nerve), in this case, a painful point is identified behind the sternocleidomastoid muscle, at the level of its upper third.

Greater auricular nerve (n. auricularis magnus, C3) innervates most of the skin auricle, parotid region and inferolateral surface of the face.

Cutaneous cervical nerve (n. cutaneus colli, C3 innervates the skin of the anterior and lateral surfaces of the neck.

Supraclavicular nerves (supraclaviculars, C3~C4^ innervate the skin of the supraclavicular region, the upper outer part of the shoulder, as well as the upper sections chest- in front to the 1st rib, behind - in the upper scapular region.

Irritation of the cervical plexus can cause spasm of the longus colli muscle and diaphragm. With tonic tension of the neck muscles, the head tilts back and to the affected side; with a bilateral spasm, the head leans back, which creates the impression of stiff neck muscles. With bilateral paralysis of the cervical muscles, the head hangs helplessly forward, as happens in some cases of myasthenia gravis, poliomyelitis or tick-borne encephalitis.

Isolated lesions of the cervical plexus may be caused by trauma or tumor at the upper cervical level.

8.3.5. Brachial plexus and its nerves

Brachial plexus (plexus brachialis) formed from the anterior branches of the C5 Th1 spinal nerves (Fig. 8.3).

The spinal nerves, from which the brachial plexus is formed, leave the spinal canal through the corresponding intervertebral foramina, passing between the anterior and posterior intertransverse muscles. The anterior branches of the spinal nerves, connecting with each other, first form 3 trunks (primary bundles) of the brachial plexus, constituting its supraclavicular part, each of which is connected by means of white connecting branches to the middle or lower cervical vegetative nodes.

1. Upper trunk occurs as a result of the connection of the anterior branches of the C5 and C6 spinal nerves.

2. Medium trunk is a continuation of the anterior branch of the C7 spinal nerve.

3. Lower trunk consists of the anterior branches of the C8, Th1 and Th2 spinal nerves.

The trunks of the brachial plexus descend between the anterior and middle scalene muscles above and behind the subclavian artery and pass into the subclavian part of the brachial plexus, located in the area of ​​the subclavian and axillary fossae.

At the subclavian level each of the trunks (primary bundles) of the brachial plexus is divided into anterior and posterior branches, from which 3 bundles (secondary bundles) are formed, constituting the infraclavicular part of the brachial plexus and named depending on their location relative to the axillary artery (a. axillaris), which they surround.

1. Posterior bun formed by the fusion of all three posterior branches of the trunks of the supraclavicular part of the plexus. It starts from him axillary and radial nerves.

2. Lateral bundle constitute the connected anterior branches of the upper and partially middle trunks (C5 C6 I, C7). From this bunch they originate musculocutaneous nerve and part(outer leg - C7) median nerve.

3. Medial bundle is a continuation of the anterior branch of the lower primary bundle; from it are formed ulnar nerve, cutaneous medial nerves of the shoulder and forearm, and part of the median nerve(internal leg - C8), which connects to the external leg (in front of the axillary artery), together they form a single trunk of the median nerve.

The nerves formed in the brachial plexus belong to the nerves of the neck, shoulder girdle and arm.

Nerves of the neck. Short muscle branches participate in the innervation of the neck (rr. musculares), innervating deep muscles: intertransverse muscles (t. intertrasversarif); longus colli muscle (t. longus colli), tilting the head in one direction, and when both muscles contract, tilting it forward; front, middle and back scalene muscles (t. scaleni anterior, medius, posterior), which, with a fixed chest, tilt the cervical spine in their direction, and with bilateral contraction, tilt it forward; if the neck is fixed, then the scalene muscles, contracting, raise the 1st and 2nd ribs.

Nerves of the shoulder girdle. The nerves of the brachial girdle begin from the supraclavicular part of the brachial plexus and are primarily motor in function.

1. Subclavian nerve (n. subclavius, C5-C6) innervates the subclavian muscle (i.e. subclavius), which, when contracted, moves the clavicle down and medially.

2. Anterior thoracic nerves (thoracales anteriores, C5-Th1) innervate the pectoralis major and minor muscles (tp. pectorales major et minor). Contraction of the first of them causes adduction and internal rotation of the shoulder, contraction of the second causes displacement of the scapula forward and downward.

3. Suprascapular nerve (n. suprascapular, C5-C6) innervates the supraspinatus and infraspinatus muscles (t. supraspinatus et t. infraspinatus); the first one contributes

abduction of the shoulder, the second - rotates it outward. The sensory branches of this nerve innervate the shoulder joint.

4. Subscapular nerves (subscapulars, C5-C7) innervate the subscapularis muscle (t. subscapularis), internally rotating shoulder, and teres major muscle (t. teres major), which rotates the shoulder inward (pronation), takes it back and leads it to the body.

5. Posterior thoracic nerves (nn, toracae posteriores): dorsal nerve of the scapula (p. dorsalis scapulae) and long thoracic nerve (n. thoracalis longus, C5-C7) innervate muscles, the contraction of which ensures mobility of the scapula (t. levator scapulae, t. rhomboideus, m. serratus anterior). The last of them helps to raise the arm above the horizontal level. Damage to the posterior thoracic nerves leads to scapular asymmetry. When moving in shoulder joint winged scapula on the affected side is characteristic.

6. Thoracodorsal nerve (thoracodorsal nerve, C7-C8) innervates the latissimus dorsi muscle (t. latissimus dorsi), which brings the shoulder to the body, pulls it back towards midline and rotates inward.

Nerves of the hand. The nerves of the arm are formed from secondary bundles of the brachial plexus. The axillary and radial nerves are formed from the posterior longitudinal fascicle, and the musculocutaneous nerve and the external peduncle of the median nerve are formed from the external secondary fascicle; from the secondary internal bundle - the ulnar nerve, the internal leg of the median nerve and the medial cutaneous nerves of the shoulder and forearm.

1. Axillary nerve (n. axillaris, C5-C7) - mixed; innervates the deltoid muscle (t. deltoideus), which, when contracted, abducts the shoulder to a horizontal level and pulls it back or forward, as well as the teres minor muscle (i.e. teres minor), externally rotating the shoulder.

Sensory branch of the axillary nerve - superior external cutaneous nerve of the shoulder (n. cutaneus brachii lateralis superior)- innervates the skin over the deltoid muscle, as well as the skin of the outer and partly the posterior surface of the upper arm (Fig. 8.4).

When the axillary nerve is damaged, the arm hangs like a whip, and it is impossible to move the shoulder forward or backward.

2. Radial nerve (n. radialis, C7 partlyC6, C8, Th1 ) - mixed; but predominantly motor, innervates mainly the extensor muscles of the forearm - the triceps brachii muscle (t. triceps brachii) and elbow muscle (i.e. apponens), extensors of the hand and fingers - long and short extensor carpi radialis (vol. extensor carpi radialis longus et brevis) and extensor digitorum (i.e. extensor digitorum), forearm instep support (i.e. supinator), brachioradialis muscle (t. brachioradialis), taking part in the flexion and pronation of the forearm, as well as the muscles of the abductor thumb brushes (t. abductor pollicis longus et brevis), extensor pollicis brevis and longus (t. extensor pollicis brevis et longus), extensor index finger (i.e. extensor indicis).

Sensory fibers of the radial nerve make up the posterior cutaneous branch of the shoulder (n. cutaneus brachii posteriores), providing sensitivity to the back of the shoulder; inferior lateral cutaneous nerve of the shoulder (n. cutaneus brachii lateralis inferior), innervating the skin of the lower outer part of the shoulder, and the posterior cutaneous nerve of the forearm (n. cutaneus antebrachii posterior), determining the sensitivity of the posterior surface of the forearm, as well as the superficial branch (ramus superficialis), participating in the innervation of the dorsum of the hand, as well as the posterior surface of the I, II and half of the III fingers (Fig. 8.4, Fig. 8.5).

A characteristic sign of damage to the radial nerve is a drooping hand in a pronated position (Fig. 8.6). Due to paresis or paralysis of the corresponding muscles, extension of the hand, fingers and thumb, as well as supination of the hand with the extended forearm are impossible; the carporadial periosteal reflex is reduced or not evoked. In the case of high damage to the radial nerve, the extension of the forearm is also impaired due to paralysis of the triceps brachii muscle, while the tendon reflex from the triceps brachii muscle is not evoked.

If you put your palms next to each other and then try to separate them, then on the side of the lesion of the radial nerve the fingers do not straighten, sliding along the palmar surface of the healthy hand (Fig. 8.7).

The radial nerve is very vulnerable; in terms of the frequency of traumatic lesions, it ranks first among all peripheral nerves. Damage to the radial nerve occurs especially often with shoulder fractures. Often the cause of damage to the radial nerve is also infection or intoxication, including chronic intoxication alcohol.

3. Musculocutaneous nerve (n. musculocutaneus, C5-C6) - mixed; motor fibers innervate the biceps brachii muscle (i.e. biceps brachii), flexor arm at the elbow joint and supinating bent forearm, as well as the brachialis muscle (t. brachialis) y involved in flexion of the forearm, and the coracobrachialis muscle (ie coracobrachial^^ promoting anterior elevation of the shoulder.

Sensitive fibers of the musculocutaneous nerve form its branch - the external cutaneous nerve of the forearm (p. cutaneus antebrachii lateralis), providing sensitivity to the skin of the radial side of the forearm up to the eminence of the thumb.

When the musculocutaneous nerve is damaged, flexion of the forearm is impaired. This is especially clear when the forearm is supinated, since flexion of the pronated forearm is possible due to the brachioradialis muscle innervated by the radial nerve. (t. brachioradialis). Also characteristic is loss of the tendon reflex from the biceps brachii muscle, raising the shoulder anteriorly. Sensory disturbances can be detected on the outer side of the forearm (Fig. 8.4).

4. Median nerve (n. medianus ) - mixed; formed from part of the fibers of the medial and lateral bundle of the brachial plexus. At the level of the shoulder, the median nerve does not give branches. Muscular branches extending from it to the forearm and hand (rami musculares) innervate the pronator teres (i.e. pronator teres), pronates the forearm and promotes its flexion. Flexor carpi radialis (t. flexor carpi radialis) along with flexion of the wrist, it abducts the hand to the radial side and participates in flexion of the forearm. Palmaris longus muscle (t. palmaris longus) stretches the palmar aponeurosis and participates in flexion of the hand and forearm. Flexor digitorum superficialis (t. digitorum superficialis) bends the middle phalanges of the II-V fingers, participates in flexion of the hand. In the upper third of the forearm, the palmar branch of the median nerve departs from the median nerve (ramus palmaris n. mediant). It passes in front of the interosseous septum between the flexor pollicis longus and flexor digitorum profundus muscles and innervates the flexor pollicis longus muscle. (i.e. flexor pollicis longus), flexing the nail phalanx of the thumb; part of the deep flexor digitorum flexing the nail and middle phalanges of the II-III fingers and hand; pronator quadratus (i.e. pronator quadratus), pronating the forearm and hand.

At the level of the wrist, the median nerve divides into 3 common palmar digital nerves (pp. digitaks palmares communes) and the own palmar digital nerves arising from them (pp. digitaks palmares proprii). They innervate the abductor pollicis brevis muscle (i.e. abductor pollicis brevis), muscle that opposes the thumb (i.e. opponens policis), flexor pollicis brevis (t. flexor pollicis brevis) and I-11 lumbrical muscles (mm. lumbricales).

Sensory fibers of the median nerve innervate the skin in the area wrist joint(its anterior surface), the eminence of the thumb (thenar), I, I, III fingers and the radial side of the IV finger, as well as the dorsal surface of the middle and distal phalanges II and III fingers (Fig. 8.5).

Damage to the median nerve is characterized by a violation of the ability of the thumb to oppose the rest, while the muscles of the eminence of the thumb atrophy over time. The thumb in such cases ends up in the same plane as the rest. As a result, the palm takes on the typical shape of the median nerve lesion, known as the “monkey hand” (Fig. 8.8a). If the median nerve is affected at the level of the shoulder, a disorder occurs in all functions depending on its condition.

To identify impaired functions of the median nerve, the following tests can be performed: a) when trying to clench the hand into a fist, fingers I, II and partly III remain straightened (Fig. 8.86); if the palm is pressed to the table, then the scratching movement with the nail of the index finger is not possible; c) to hold a strip of paper between the thumb and index finger, due to the inability to bend the thumb, the patient brings the straightened thumb to the index finger - thumb test.

Due to the fact that the median nerve contains a large number of autonomic fibers, when it is damaged, trophic disorders are usually pronounced and more often than when any other nerve is damaged, causalgia develops, manifested in the form of a sharp, burning, diffuse pain.

5. Ulnar nerve (n. ulnaris, C8-Th1) - mixed; it begins in the axillary fossa from the medial bundle of the brachial plexus, descends parallel to the axillary and then the brachial artery and goes to the internal condyle humerus and at the level of the distal part of the shoulder it runs along the groove of the ulnar nerve (sulcus nervi ulnaris). In the upper third of the forearm, branches depart from the ulnar nerve to the following muscles: flexor carpi ulnaris (t. flexor carpi ulnaris), flexor and adductor wrist; medial part of the deep flexor digitorum (i.e. flexor digitorum profundus), flexing the nail phalanx of the IV and V fingers. In the middle third of the forearm, the cutaneous palmar branch departs from the ulnar nerve (ramus cutaneus palmaris), innervating the skin of the medial side of the palm in the area of ​​the eminence of the little finger (hypotenar).

At the border between the middle and lower third of the forearm, the dorsal branch of the hand is separated from the ulnar nerve (ramus dorsalis manus) and palmar branch of the hand (ramus volaris manus). The first of these branches is sensitive; it extends to the back of the hand, where it branches into the dorsal nerves of the fingers (pp. digitales dorsales), which end in the skin of the dorsal surface of the V and IV fingers and the ulnar side of the III finger, while the nerve of the V finger reaches its nail phalanx, and the rest reach only the middle phalanges. The second branch is mixed; its motor part is directed to the palmar surface of the hand and at the level of the pisiform bone is divided into superficial and deep branches. The superficial branch innervates the palmaris brevis muscle, which pulls the skin to the palmar aponeurosis; it is further divided into common and proper palmar digital nerves (pp. digitales pa/mares communis et proprii). The common digital nerve innervates the palmar surface of the fourth finger and the medial side of its middle and terminal phalanges, as well as back side nail phalanx of the fifth finger. The deep branch penetrates deep into the palm, goes to the radial side of the hand and innervates the following muscles: the adductor magnus muscle (i.e. adductor policis), adductor V finger (i.e. abductor digiti minim f), flexor main phalanx of the fifth finger, muscle opposing the fifth finger (i.e. opponens digiti minimi) - she brings the little finger to the midline of the hand and opposes it; deep head of flexor pollicis brevis (t. flexor pollicis brevis); lumbrical muscles (tt. lumbricales), muscles that flex the main and extend the middle and nail phalanges of the II and IV fingers; palmar and dorsal interosseous muscles (vol. interossei palmales et dorsales), bending the main phalanges and simultaneously extending the other phalanges of the II-V fingers, as well as abducting the II and IV fingers from the middle (III) finger and leading the II, IV and V fingers to the middle.

Sensitive fibers of the ulnar nerve innervate the skin of the ulnar edge of the hand, the dorsum of the fifth and partly fourth fingers, and the palmar surface of the fifth, fourth and partly third fingers (Fig. 8.4, 8.5).

In cases of damage to the ulnar nerve, due to developing atrophy of the interosseous muscles, as well as hyperextension of the main and flexion of the remaining phalanges of the fingers, a claw-shaped hand is formed, reminiscent of a bird's paw (Fig. 8.9a).

To identify signs of damage to the ulnar nerve, the following tests can be performed: a) when trying to clench the hand into a fist, fingers V, IV and partly III are not bent enough (Fig. 8.96); b) scratching movements with the nail of the little finger with the palm pressed tightly to the table are not successful; c) if the palm lies on the table, then spreading and bringing the fingers together fails; d) the patient cannot hold a strip of paper between the index finger and straightened thumb. To hold it, the patient needs to sharply bend the terminal phalanx of the thumb (Fig. 8.10).

6. Cutaneous internal nerve of the shoulder (n. cutaneus brachii medialis, C8-Th1 - sensitive, originates from the medial bundle of the brachial plexus, at the level of the axillary fossa has connections with the external cutaneous branches (rr. cutani laterales) II and III thoracic nerves (pp. thoracales) and innervates the skin of the medial surface of the shoulder to the elbow joint (Fig. 8.4).

IN right hand pressing a strip of paper is possible only with a straightened thumb due to its adductor muscle, innervated by the ulnar nerve (a sign of damage to the median nerve). On the left, pressing the strip of paper is carried out due to the long muscle flexor of the thumb innervated by the median nerve (a sign of damage to the ulnar nerve).

7. Cutaneous internal nerve of the forearm (n. cutaneus antebrachii medialis, C8-7h2 ) - sensitive, originates from the medial bundle of the brachial plexus, is located in the axillary fossa next to the ulnar nerve, descends along the shoulder in the medial groove of its biceps muscle, innervates the skin of the inner surface of the forearm (Fig. 8.4).

Brachial plexus lesion syndromes. Along with isolated damage to individual nerves emerging from the brachial plexus, damage to the plexus itself is possible. Plexus damage is called plexopathy.

The etiological factors of damage to the brachial plexus are gunshot wounds of the supra- and subclavian areas, fracture of the clavicle, first rib, periostitis of the first rib, dislocation of the humerus. Sometimes the plexus is affected due to its overstretching, when the arm is quickly and strongly pulled back. Damage to the plexus is also possible in a position where the head is turned in the opposite direction and the hand is placed behind the head. Brachial plexopathy can be observed in newborns due to traumatic injury during complicated childbirth. Damage to the brachial plexus can also be caused by carrying heavy weights on the shoulders or on the back, especially with general intoxication with alcohol, lead, etc. Compression of the plexus can be caused by an aneurysm of the subclavian artery, additional cervical ribs, hematomas, abscesses and tumors of the supra- and subclavian region.

Total brachial plexopathy leads to flaccid paralysis of all muscles of the shoulder girdle and arm, while only the ability to “raise the shoulder girdle” may be preserved due to the preserved function of the trapezius muscle, innervated by the accessory cranial nerve and the posterior branches of the cervical and thoracic nerves.

In accordance with anatomical structure The brachial plexus differs in syndromes of damage to its trunks (primary bundles) and bundles (secondary bundles).

Syndromes of damage to the trunks (primary bundles) of the brachial plexus occur when the supraclavicular part is damaged, and syndromes of damage to the upper, middle and lower trunks can be distinguished.

I.Superior brachial plexus syndrome (the so-called upper Erb-Duchenne brachial plexopathy occurs when there is damage (usually traumatic) to the anterior branches of the V and VI cervical spinal nerves or the part of the plexus in which these nerves connect, forming the superior trunk after passing between the scalene muscles. This place is located 2-4 cm above the collarbone, approximately a finger's width behind the sternocleidomastoid muscle and is called Erb's supraclavicular point.

Upper brachial Erb-Duchenne plexopathy is characterized by a combination of signs of damage to the axillary nerve, long thoracic nerve, anterior thoracic nerves, subscapular nerve, dorsal scapular nerve, musculocutaneous and part of the radial nerve. Characterized by paralysis of the muscles of the shoulder girdle and proximal parts of the arm (deltoid, biceps, brachialis, brachioradialis and supinator muscles), shoulder abduction, flexion and supination of the forearm are impaired. As a result, the arm hangs like a whip, is adducted and pronated, the patient cannot raise his arm or bring his hand to his mouth. If you passively supinate your arm, it will immediately turn inward again. The reflex from the biceps muscle and the wrist (carporadial) reflex are not evoked, and radicular type hypalgesia usually occurs on the outer side of the shoulder and forearm in the dermatome zone C v -C VI. Palpation reveals pain in the area of ​​Erb's supraclavicular point. A few weeks after the plexus is damaged, increasing wasting of the paralyzed muscles appears.

Erb-Duchenne brachial plexopathy most often occurs due to injuries, it is possible, in particular, when falling on an outstretched arm, it can be a consequence of compression of the plexus during a long stay with the arms placed under the head. Sometimes it appears in newborns during pathological births.

2. Middle trunk brachial plexus syndrome occurs when the anterior branch of the VII cervical spinal nerve is damaged. In this case, violations of the extension of the shoulder, hand and fingers are characteristic. However, the triceps brachii muscle, the extensor pollicis muscle and the abductor pollicis longus muscle are not completely affected, since, along with the fibers of the VII cervical spinal nerve, fibers that came into the plexus along the anterior branches of the V and VI cervical spinal nerves also participate in their innervation. This circumstance is an important sign when carrying out differential diagnosis syndrome of lesions of the middle trunk of the brachial plexus and selective lesions of the radial nerve. The reflex from the triceps tendon and the radiocarpal (carporadial) reflex are not evoked. Sensory disturbances are limited to a narrow strip of hypalgesia on the dorsum of the forearm and the radial part of the dorsum of the hand.

3. Syndrome of the lower trunk of the brachial plexus (inferior brachial plexopathy Dejerine-Klumpke) occurs when the nerve fibers entering the plexus along the VIII cervical and I thoracic spinal nerves are damaged, with signs of damage to the ulnar nerve and cutaneous internal nerves of the shoulder and forearm, as well as part of the median nerve (its internal leg) ). In this regard, with Dejerine-Klumke paralysis, paralysis or paresis of the muscles occurs mainly in the distal part of the arm. The ulnar part of the forearm and hand suffers mainly, where sensory disturbances and vasomotor disorders are detected. Extension and abduction of the thumb are impossible or difficult due to paresis of the short extensor pollicis and the abductor pollicis muscle, innervated by the radial nerve, since the impulses going to these muscles pass through the fibers that are part of the VIII cervical and I thoracic spinal nerves and the lower trunk of the brachial plexus. Sensation in the arm is impaired on the medial side of the shoulder, forearm and hand. If, simultaneously with the damage to the brachial plexus, the white connecting branches going to the stellate ganglion are also affected (ganglion stellatum), That possible manifestations of Horner's syndrome(narrowing of the pupil, palpebral fissure and mild enophthalmos. In contrast to combined paralysis of the median and ulnar nerves, the function of the muscles innervated by the external leg of the median nerve is preserved in the syndrome of the lower trunk of the brachial plexus.

Dejerine-Klumke's palsy most often occurs due to traumatic injury brachial plexus, but may also be a consequence of compression by a cervical rib or a Pancoast tumor.

Syndromes of damage to the bundles (secondary bundles) of the brachial plexus arise from pathological processes and injuries in the subclavian region and are in turn divided into lateral, medial and posterior bundle syndromes. These syndromes practically correspond to the clinical picture of combined lesions of peripheral nerves formed from the corresponding bundles of the brachial plexus. The lateral fascicle syndrome is manifested by dysfunction of the musculocutaneous nerve and the upper peduncle of the median nerve, the posterior fascicle syndrome is characterized by dysfunction of the axillary and radial nerves, and the medial fascicle syndrome is expressed by dysfunction of the ulnar nerve, the medial peduncle of the median nerve, the medial cutaneous nerves of the shoulder and forearms. When two or three (all) bundles of the brachial plexus are affected, a corresponding summation occurs clinical signs, characteristic of syndromes in which individual bundles of it are affected.

8.3.6. Thoracic nerves

Thoracic nerves (pp. thoracalis) It is customary to call the spinal nerves of the thoracic level. Like other spinal nerves, the thoracic nerves are divided into posterior and anterior branches. Posterior branches (rami posteriores) bend around the articular processes of the vertebrae and are directed between the transverse processes to the back, where they are in turn divided into internal and lateral branches, providing innervation to paravertebral tissues, in particular long back muscle (t. longissimus dorsi), semispinalis muscle (t. semispinalis), sacral spinal muscle (t. sacrospinal), and multifidus, rotating, interspinous And intertransverse muscles. All these long and short muscles of the back support the torso in an upright position, extend or flex the spine, and when they contract on one side, the spine flexes or rotates in that direction.

Part of the fibers of the anterior branches of the first and second thoracic spinal nerves takes part in the formation of the brachial plexus, part of the anterior branch of the XII thoracic spinal nerve is part of the lumbar plexus. The parts not involved in the formation of plexuses (Th1-Th2 and Th12) and the anterior branches of the thoracic spinal nerves (Th3-Th11 |) form intercostal nerves (pp. intercostales). The six superior intercostal nerves pass to the edge of the sternum and end as the anterior cutaneous thoracic branches; The six lower intercostal nerves pass behind the corners of the costal cartilages into the thickness of the abdominal muscles and are located there first between the transverse and internal oblique muscles, approach the rectus abdominis muscle and end as cutaneous anterior abdominal nerves.

The intercostal nerves are mixed and play an important role in the innervation of the muscles of the chest and abdomen involved in the act of breathing.

At irritation of intercostal nerves(in a pathological process) there is a girdle pain, increasing with breathing movements, especially when coughing, sneezing. Pain on palpation of certain intercostal spaces is common, pain points are possible: posterior - in the paravertebral region, lateral - along the axillary line and anterior - along the line of connection of the sternum with the costal cartilages; a decrease in the amplitude of respiratory movements is possible. Damage to the lower intercostal nerves causes paresis of the muscles of the abdominal wall, accompanied by the loss of the corresponding abdominal reflexes, the arcs of which pass through the VII-XII segments of the spinal cord, with exhalation, coughing, and sneezing especially difficult. Difficulty urinating and defecating is common. In addition, the lordosis of the lumbar spine becomes excessive with the pelvis moving forward; when walking, he leans back, a duck's gait appears.

Sensitivity when the thoracic nerves are damaged can be impaired in the chest, abdomen, armpits and on the inner surface of the shoulder due to the lesion n. intercostobrachialis.

Damage to the thoracic nerves may be a consequence of spinal pathology, ganglioneuropathy in herpes zoster, rib fractures, inflammatory and oncological diseases organs of the chest, with intravertebral tumors, in particular neuroma.

The lumbar spinal roots depart from the corresponding segments of the spinal cord at the level of the X-XII thoracic vertebrae and go down to the intervertebral foramina of the same name, each of which is located below the vertebra of the same name. Here, the corresponding spinal nerves are formed from the anterior and posterior roots. After passing through the intervertebral foramina, they are divided into branches. The posterior and anterior branches of the spinal nerves, as at other levels of the spine, are mixed in composition.

The posterior branches of the lumbar spinal nerves are divided into medial and lateral branches. The medial branches innervate the lower parts of the deep back muscles and provide skin sensitivity in the paravertebral zone of the lumbar region. The lateral branches innervate the lumbar intertransverse and multifidus muscles. The superior gluteal nerves arise from the three superior lateral rami (pp. sip "piece superiores), running through the iliac crest to the skin of the upper half of the gluteal region, i.e. to the skin over the gluteus maximus and medius muscles up to greater trochanter hips.

8.3.7. Lumbar plexus and its nerves

The anterior branches of the lumbar spinal nerves take part in the formation of the lumbar plexus (plexus lumbalis). This plexus (Fig. 8.11) consists of loops formed by the anterior branches of L1-L3 and partially Th12 and L4 spinal nerves. The lumbar plexus is located in front of the transverse processes of the lumbar vertebrae on the anterior surface of the quadratus lumborum muscle between the bundles of the psoas major muscle. The lumbar plexus has numerous connections with the underlying sacral plexus. Therefore, they are often combined under the name lumbosacral plexus. Most of the peripheral nerves emerging from the lumbar plexus are mixed in composition. However, there are also muscle branches (rami musculares), innervating, in particular, the internal muscles of the pelvis: the iliopsoas muscle (t. iliopsoas) and psoas minor muscle (i.e. psoas minor), hip flexors hip joint, as well as the quadratus lumborum muscle, which rotates the thigh outward.

Iliohypogastric nerve (n. iliohypogastricus, Th12~L1 ) goes obliquely down parallel to the XII intercostal nerve, penetrates the transverse abdominal muscle, passes between it and the internal oblique abdominal muscle. At the level of the inguinal (pupart) ligament, the nerve passes through the internal oblique muscle of the abdomen and is located between it and the aponeurosis of the external oblique muscle. Along the way, branches depart from the iliohypogastric nerve to the muscles of the lower abdomen and the external cutaneous branch, which separates in the area of ​​the middle part of the iliac crest, pierces the oblique muscles of the abdomen and innervates the area of ​​​​the skin over the gluteus medius and the muscle that tenses the fascia of the thigh. In addition, an anterior cutaneous branch arises from the iliohypogastric nerve, which pierces the anterior wall of the inguinal canal and innervates the skin above and medial to the external opening of the inguinal canal.

Ilioinguinal nerve (n. Uioingui-nalis, L1) runs parallel to and below the iliohypogastric nerve, pierces the transverse abdominis muscle and goes further between it and the internal oblique abdominal muscle, passes over the Pupart ligament and exits under the skin through the external inguinal ring, then it is located medially and in front spermatic cord and is divided into terminal sensory branches.

Along the path of the ilioinguinal nerve, muscle branches depart from it to the external and internal oblique muscles of the abdomen and the transverse abdominal muscle, cutaneous branches providing sensitivity in the groin area and in the upper part of the inner surface of the thigh, as well as anterior scrotal branches innervating the skin of the pubic area , the root of the penis and the anterior part of the scrotum (in women - the skin of the labia majora) and the upper part of the medial part of the thigh.

Genitofemoral nerve (n. genitofemoral is, L1~L3) passes between the transverse processes of the lumbar vertebrae and the psoas major muscle. It then passes down through the thickness of this muscle and appears on its anterior surface at the level of the L3 vertebra. Here he is divided into femoral and genital branches.

Femoral branch passes downward laterally from the femoral vessels under the ligament of Pou-Part, where it branches: part of the branches passes through the foramen ovale, the other part is lateral from it; the last group of branches is distributed in the skin below the inguinal fold along the anterior surface of the thigh (Fig. 8.12).

Sexual branch descends along the inner edge of the psoas major muscle, penetrates the inguinal canal through it back wall, approaches the posterior surface of the spermatic cord (in women - to the round uterine ligament) and reaches the scrotum (labia majora). On its way, this nerve gives off branches to t. cremaster and cutaneous branches.

Rice. 8.12. Innervation of the skin of the posterior (a) and anterior (b) surface of the leg. 1 - superior gluteal nerve; 2 - posterior sacral nerves; 3 - middle gluteal nerve; 4 - posterior cutaneous nerve of the thigh; 5 - external cutaneous nerve of the thigh; 6 - obturator nerve; 7 - external cutaneous sural nerve (branch of the peroneal nerve); 8 - nervus saphenus (branch of the femoral nerve); 9 - internal cutaneous sural nerve (branch of the tibial nerve); 10 - calcaneal branch of the tibial nerve; 11 - external plantar nerves (branches of the tibial nerve); 12 - internal plantar nerves; 13 - sural nerve (branch of the tibial and peroneal nerves); 14 - deep peroneal nerve; 15 - superficial peroneal nerve; 16 - external cutaneous nerve of the thigh; 17 - inguinal nerve; 18 - genital femoral nerve.

When the genitofemoral nerve is damaged, the cutaneous cremasteric reflex disappears. Sensitive nerve fibers innervate the skin of the groin area and the upper part of the inner thigh.

Obturator nerve (n. obturatorius, L2 -L4) innervates the pectineus muscle (t. pectineus), involved in adduction and flexion of the hip, the adductor magnus muscle (i.e. adductor longus), which flexes the thigh and rotates it outward; and adductor brevis muscle (i.e. adductor brevis), adductor of the thigh and involved in its flexion, as well as the adductor magnus muscle (i.e. adductorius magnus), which adducts the thigh and is involved in its extension, the external anterior muscle (n. obturatorius externus), contraction of which leads to outward rotation of the thigh, as well as the gracilis muscle (t. gracilis), adducting the thigh, flexing the tibia and simultaneously rotating it inward. Sensory fibers of the obturator nerve (rr. cutanei n. obturatorii) innervate the skin of the lower part of the inner thigh. When the obturator nerve is damaged, hip adduction and, to a lesser extent, hip abduction and rotation are weakened. When walking, some excess hip abduction may be noted. It is difficult for a patient sitting on a chair to lie down sore leg to a healthy one.

external cutaneous nerve of the thigh (n. cutaneus femoris lateralis, L2 - L3 / ) passes under the Poupart ligament and 3-5 cm below it divides into branches that innervate the skin of the outer surface of the thigh. Isolated damage to the external cutaneous nerve of the thigh occurs quite often and leads to the development of Roth's disease, which has a different etiology (usually compression of the nerve) and is manifested by paresthesia and hypalgesia with elements of hyperpathy on the anterior outer surface of the thigh.

Femoral nerve (n. femora lis, L2-L4) - most major nerve lumbar plexus. It innervates the quadriceps femoris muscle (m. quadriceps femoris), which includes the rectus muscle, as well as the lateral, intermediate and medial vastus muscles. The quadriceps femoris muscle is primarily a powerful extensor of the lower leg in knee joint. In addition, the femoral nerve innervates the sartorius muscle (t. sartorius), taking part in flexing the leg at the hip and knee joints and rotating the thigh outward.

Anterior cutaneous nerves (rr. cutanei anteriores) And saphenous nerve (p. saphenus), being the terminal branch of the femoral nerve, passing to the lower leg, it provides innervation to the skin of the anterior inner surface of the thigh and lower leg and the medial side of the foot to the big toe.

If the femoral nerve below the Poupart ligament is damaged, leg extension is impaired, the knee reflex decreases or disappears, and a sensitivity disorder occurs in the area innervated by the saphenus. If the femoral nerve is damaged above the Pupart ligament, then at the same time the sensitivity on the anterior inner surface of the thigh is impaired and the ability to actively flex it is difficult. It is difficult for a patient lying on his back with straightened legs to sit up without the help of his hands, and with bilateral damage to the femoral nerves this becomes impossible.

Damage to the femoral nerve makes walking, running, and especially climbing stairs very difficult. When walking on level ground, the patient tries not to bend the leg at the knee joint. When walking, the patient's leg, bent at the knee joint, is thrown forward and at the same time the heel hits the floor.

When the femoral nerve is damaged due to a decrease in tone and then hypotrophy of the quadriceps muscle, the anterior surface of the thigh flattens and a depression appears above the patella, which is revealed when examining the patient lying on his back (Flatau-Sterling symptom).

If there is a lesion of the femoral nerve, then in a standing patient, when he transfers the center of gravity and relies only on the extended sore leg, free passive displacement of the patella to the sides is possible (symptom of a dangling patella, Froman's symptom).

If the femoral nerve is irritated, pain and tenderness may occur in the area of ​​the ligament and on the front side of the thigh. In such cases, the symptoms of Wasserman, Matskevich, related to the symptoms of tension, and the Seletsky phenomenon are positive.

Wasserman's sign is checked with the patient lying on his stomach. The examiner strives to extend the leg at the hip joint as much as possible, while at the same time fixing his pelvis at the bedside. In case of irritation of the femoral nerve, the patient experiences pain in the groin area, radiating along the anterior surface of the thigh.

Matskevich's symptom is caused in the same position of the patient by sharply bending the lower leg and bringing it closer to the thigh. As a result, the patient experiences the same reactions as when checking Wasserman's symptom. The protective reaction that occurs when these tension symptoms are caused - raising the pelvis - is known as Seletsky phenomenon.

8.3.8. Sacral plexus and its nerves

The sacral spinal nerves arise from the sacral segments of the spinal cord at the level of the body of the first lumbar vertebra and descend down into the sacral canal, at the level of which the sacral spinal nerves are formed in the area of ​​the intervertebral foramina of the sacrum due to the fusion of the anterior and posterior spinal roots. These nerves are divided into anterior and posterior branches, leaving the sacral canal through the intervertebral foramina of the sacrum, with the anterior branches exiting onto the pelvic surface of the sacrum (into the pelvic cavity), and the posterior branches onto its dorsal surface. The branches of the fifth sacral spinal nerve exit the sacral canal through the sacral fissure (hiatus sacralis).

The posterior branches, in turn, are divided into internal and external. The internal branches innervate the lower segments of the deep muscles of the back and end with cutaneous branches in the sacrum, closer to the midline. The external branches of the I-III sacral spinal nerves are directed downward and are called the middle cutaneous nerves of the buttocks (pp. clunium medii), innervating the skin of the middle parts of the gluteal region.

The anterior branches of the sacral nerves, emerging through the anterior sacral foramina onto the pelvic surface of the sacral bone, form the sacral plexus.

Sacral plexus (plexus sacralis) consists of loops formed by the anterior branches of the lumbar and sacral spinal nerves (L5-S2 and partially L4 and S3). The sacral plexus, which has numerous connections with the lumbar plexus, is located in front of the sacrum, on the anterior surface of the piriformis and partly coccygeal muscles on the sides of the rectum and goes down to the greater sciatic notch (incisure ischiadica major), through which the peripheral nerves formed in the sacral plexus leave the pelvic cavity.

The muscular branches of the sacral plexus innervate the following muscles: a) piriformis muscle (t. piriformis), which is located between the anterior surface of the sacrum and the inner surface of the greater trochanter of the femur. Crossing the greater sciatic foramen, this muscle divides it into supra- and infrapiriform parts, through which vessels and nerves pass; b) internal obturator muscle (i.e. obturatorius internus), located inside the pelvis; c) upper and outer muscles of the twins (t. gemelles superior et inferior)"., G) quadratus femoris muscle. All of these muscles externally rotate the hip. To determine their strength can be carried out following tests: 1) the patient, lying on his stomach with his lower leg bent at a right angle, is asked to move his lower leg inward, while the examiner resists this movement; 2) the patient lying on his back is asked to rotate his legs outward, while the examiner resists this movement.

Superior gluteal nerve (n. gluteus superior, L4-S1) - motor, it innervates gluteus medius and minimus muscles(mm. glutei medius et minimus), tensor fascia lata(m. tensor fasciae latae), the contraction of which leads to hip abduction. Damage to the nerve causes difficulty in hip abduction, flexion and internal rotation. With bilateral damage to the superior gluteal nerve, the patient's gait becomes like a duck's - the patient seems to waddle from one foot to the other when walking.

Lower gluteal nerve (p. gluteus inferior, L5-S2 ) is motor, innervates gluteus maximus muscle (i.e. gluteus maximus), extending the hip, and with a fixed hip, tilting the pelvis backward. If the inferior gluteal nerve is damaged, hip extension is difficult. If a standing patient bends over, then it is difficult for him to straighten his torso. The pelvis in such patients is fixed tilted forward, as a result of which compensated lordosis develops in the lumbar spine. Patients find it difficult to climb stairs, jump, or get out of a chair.

Posterior cutaneous nerve of the thigh (p, cutaneus femoris posterior, S1-S3) - sensitive. Exits through the infrapiriform foramen behind sciatic nerve, with which it has anastomoses. Next it passes between the ischial tuberosity and large skewer, goes down and innervates the skin of the back of the thigh, including the popliteal fossa. The inferior cutaneous nerves of the buttock (ll.) depart from the posterior cutaneous nerve of the thigh. clinium inferiores), perineal nerves (rr. perineales), which provide sensitivity to the corresponding skin areas.

Sciatic nerve(p. ischiadicus, L4-S3 / ) - mixed; the largest of the peripheral nerves. Its motor part innervates most of the muscles of the leg, in particular all the muscles of the lower leg and foot. Even before exiting the thigh, the sciatic nerve gives off motor branches to biceps femoris muscle (biceps femoris), semitendinosus muscle (semitendinosus) And semimembranosus muscle (t. semimembranosus), bending the lower leg at the knee joint and rotating it inward. In addition, the sciatic nerve innervates adductor magnus muscle (i.e. adductor magnus), which flexes the lower leg, rotating it outward.

Having reached the level of the thigh, the sciatic nerve passes along its posterior side and, approaching the popliteal fossa, divides into two branches - the tibial and peroneal nerves.

Tibial nerve (n. tibialis, L4-S3) is a direct continuation of the sciatic nerve. It runs down the middle of the popliteal fossa along the back of the shin to the inner ankle. Motor branches of the tibial nerve innervate the triceps surae muscle(/I. triceps surae), consisting of the soleus muscle (i.e. soleus) And calf muscle. The triceps surae muscle flexes the lower leg at the knee joint and the foot at the ankle. In addition, the tibial nerve innervates popliteus muscle (i.e. popliteus), involved in flexing the tibia at the knee joint and rotating it inward; posterior tibial muscle (t. tibialis posterior), adducting and elevating the inner edge of the foot; flexor digitorum longus (flexor digitorum longus), bending the nail phalanges of the II-V fingers; flexor pollicis longus(m. flexor hallucis longus), the contraction of which causes flexion of the first toe.

At the level of the popliteal fossa, it departs from the tibial nerve medial cutaneous nerve of the leg (n. cutaneus surae medialis), the branches of which innervate the skin of the posterior surface of the leg (Fig. 8.12). In the lower third of the leg, this cutaneous nerve anastomoses with the branch of the lateral cutaneous nerve of the leg, which arises from the peroneal nerve, and is then called sural nerve (p. suralis) descends along the lateral edge of the calcaneal (Achilles) tendon, wraps around the back of the outer ankle. Here it departs from the sural nerve lateral calcaneal branches (rr. calcanei laterales), innervating the skin of the lateral part of the heel. Next, the sural nerve goes forward to the lateral surface of the foot called lateral dorsal cutaneous nerve (n. cutaneus dorsalis lateralis) and innervates the skin of the dorsolateral surface of the foot and little toe.

Slightly above the level of the medial malleolus, they extend from the tibial nerve medial calcaneal branches (rr. rami calcanei mediates).

Having gone down to ankle joint, tibial nerve passes at the posterior edge of the inner ankle onto the sole. On inside he calcaneus divided by final branches: medial and lateral plantar nerves.

Medial plantar nerve (n. plantaris medialis ) passes under the abductor pollicis muscle, and then goes forward and divides into muscular and cutaneous branches. The muscular branches of the medial plantar nerve innervate the short flexor of the fingers (m. flexor digitorum brevis), which flexes the middle phalanges of the II-V fingers; flexor pollicis brevis (t. flexor hallucis brevis), involved in ensuring flexion of the thumb; abductor pollicis muscle (i.e. adductor hallucis), involved in flexion of the thumb and ensuring its abduction. In addition, the own plantar digital nerves arise from the medial plantar nerve. innervating the skin of the medial and plantar surface of the big toe, as well as the common plantar digital nerves (pp. digitales plantares communis), innervating the skin of the first three interdigital spaces and the plantar surface of I-III, as well as the medial side of the IV fingers. From the I and II common plantar nerves, muscle branches also extend to the I and II lumbrical muscles, flexing the main and extending the remaining phalanges of the I, II and partly III toes.

Lateral plantar nerve (p. plantaris lateralis) directed along the plantar side of the foot forward and outward, gives off branches innervating the quadratus plantar muscle (t. quadratusplantae), promoting finger flexion; flexor digitorum brevis (i.e. abductor digiti minimi), abductor and flexor of the little finger. After these branches depart, the lateral plantar nerve is divided into deep and superficial branches.

Deep branch (m. profundus) penetrates deep into the plantar surface of the foot and innervates the adductor pollicis muscle (i.e. adductor hallucis) and flexor digitorum brevis (i.e. flexor digiti minimi brevis) and III-IV lumbrical muscles (vol. lumbrica/es), flexing the main and extensor middle and nail phalanges of the IV, V and partly III toes, as well as the plantar and dorsal interosseous muscles (vol. inercostales plantares et dorsales), flexing the main and extending the remaining phalanges of the fingers, as well as abductor and adductor toes.

Superficial branch (ramus superficialis) lateral plantar nerve divides into common plantar digital nerves (pp. digitales plantares communis)) from which the 3 own plantar digital nerves arise (pp. digitales plantares proprii), innervating the skin of the fifth and lateral side of the fourth fingers, as well as the lateral part of the foot.

If the tibial nerve is damaged, it becomes impossible to flex the foot and its toes. As a result, the foot becomes fixed in the extension position (Fig. 8.13a), and therefore the so-called calcaneal foot (pes calcaneus) - When walking, the patient steps primarily on his heel and cannot rise on his toes. Atrophy of the small muscles of the foot leads to a claw-like position of the toes (to the development claw-shaped foot). In this case, spreading and bringing the toes together is difficult. Sensation on the lateral and plantar side of the foot is impaired.

If the sciatic or tibial nerves are damaged, the heel (Achilles) reflex decreases or disappears.

Common peroneal nerve (n. peroneus communis, L4-S1) - the second of the main branches of the sciatic nerve. The cutaneous external nerve of the calf arises from the common peroneal nerve (n. cutaneus surae lateralis), branching on the lateral and posterior surfaces of the leg. On the lower third of the leg, this nerve anastomoses with the cutaneous medial nerve of the leg, which is a branch of the tibial nerve, thereby forming the sural nerve (p. suralis).

Posterior to the head of the fibula, the common peroneal nerve divides into two parts: the superficial and deep peroneal nerves. (n. peroneus profundus).

Rice. 8.13.“Heel” foot with damage to the tibial nerve (a);

“dropping” foot with damage to the peroneal nerve (b).

Superficial peroneal nerve (p. peroneus superflcialis) goes down the anterior outer surface of the leg, gives branches to the long and short peroneal muscles (vol. peronei longus et brevis), abducting and lifting the outer edge of the foot and at the same time flexing it. In the middle third of the leg, this nerve exits under the skin and divides into the medial and intermediate dorsal cutaneous nerves.

Medial dorsal cutaneous nerve (nervus cutaneus dorsalis medialis) is divided into two branches: medial and lateral. The first of them is directed to the medial edge of the foot and big toe, the second - to the skin of the dorsal surface of the halves of the second and third fingers facing each other.

Intermediate dorsal cutaneous nerve (a. cutaneus dorsalis intermedius) gives off sensory branches to the skin of the knees and dorsum of the foot and is divided into medial and lateral branches. The medial branch is directed to the dorsal surface of the halves of the third and fourth fingers facing each other.

Deep peroneal nerve (a. peroneus profundus) innervates the tibialis anterior muscle (m. tibialis anterior), which extends the foot and elevates its inner edge; extensor digitorum longus (i.e. extensor digitorum longus), extensor foot, II-V fingers, as well as abductor and pronating foot; extensor pollicis brevis (i.e. extensor hallucis longus), extending and supinating the foot, as well as extending the big toe; extensor pollicis brevis (i.e. extensor digitorum brevis), extending the thumb and deflecting it to the lateral side.

If the peroneal nerve is damaged, it becomes impossible to extend the foot and toes and turn the foot outward. As a result, the foot hangs down, being slightly rotated inwards, its toes bent at the joints of the main phalanges (Fig. 8.136). Leaving the foot in this position for a long time can lead to contracture. Then they talk about development horse foot (pes equinus). When the peroneal nerve is damaged, a characteristic gait develops. Avoiding contact of the back surface of the fingers with the floor, the patient raises his leg high when walking, bending it at the hip and knee joints more than usual. The foot touches the floor first with the toe, and then with the main surface of the sole. This gait is called peroneal, equine, cockerel and is often denoted by the French word steppage(steppage). A patient with damage to the peroneal nerve cannot stand on his heels, straighten the foot and toes, or turn the foot outward.

With total damage to the sciatic nerve, naturally, the function of the tibial and peroneal nerves simultaneously suffers, which is manifested by paralysis of the foot muscles, loss of the reflex from the heel tendon (calcaneal or Achilles reflex). In addition, the flexion of the lower leg is impaired. Sensitivity in the lower leg remains intact only along the anterior internal surface in the zone of innervation of the saphenous nerve of the saphenus. With high damage to the sciatic nerve, sensory impairment also manifests itself on the back of the thigh.

If a pathological process irritates the sciatic nerve, then this is primarily manifested by severe pain, as well as pain on palpation along the nerve, especially distinct in the so-called Balle points: between the ischial tuberosity and the greater trochanter, in the popliteal fossa, behind the head of the fibula.

Rice. 8.14. Lassga symptom (first and second phases). Explanation in the text.

It has important diagnostic value in cases of damage to the sciatic nerve. Lasègue's symptom(Fig. 8.14), belonging to the group of tension symptoms. It is checked with the patient lying on his back with his legs straightened. If you try to bend the patient’s leg, which is extended at the knee joint, at the hip joint, then tension in the sciatic nerve will occur, accompanied by pain that limits the possible range of movement performed; this can be measured in angular degrees and thus objectify the angle by which it is possible to raise the leg above horizontal plane. After bending the leg at the knee joint, the tension on the sciatic nerve decreases, and at the same time the pain reaction decreases or disappears.

With damage to the sciatic nerve containing a large number of autonomic fibers and its branch - the tibial nerve, as well as with damage to the median nerve on the arm, the pain often has a causal tinge; possible and pronounced violations tissue trophism, in particular trophic ulcers (Fig. 8.15).

8.3.9. Pudendal plexus

Pudendal plexus (plexus pudendus) is formed mainly from the anterior branches of the III-IV and parts of the I-II sacral spinal nerves. It is located on the anterior surface of the sacrum at the lower edge of the piriformis muscle, below the sacral plexus. The pudendal plexus has connections with the coccygeal plexus and the sympathetic trunk. Muscular branches depart from the pudendal plexus that innervate the levator muscle. anus (i.e. levator ant), coccygeus muscle (t. coccygeus) and the dorsal nerve of the penis or clitoris. The largest branch of the pudendal plexus is pudendal nerve (n. pudendus)- exits the pelvic cavity above the piriformis muscle, goes around the ischial tubercle and through the lesser sciatic foramen reaches the lateral wall of the ischiorectal fossa, in which the lower rectal nerves, the nerves of the perineum, depart from the pudendal nerve.

8.3.10. Coccygeal plexus

The coccygeal plexus is formed by part of the anterior branches of the V sacral (S5) and I-II coccygeal (Co1-Co2) nerves. The plexus is located on both sides of the sacrum, in front of the coccygeus muscle. It has connections with the lower part of the sympathetic trunk. Muscular branches depart from it to the pelvic organs and pelvic floor muscles, to the coccygeus muscle and to the levator ani muscle, as well as the anal-coccygeal nerves (pp. anococcygef), innervating the skin between the coccyx and the anus.

The clinical picture of damage to the pudendal and coccygeal plexus is manifested by a disorder of urination, defecation, genital function, loss of the anal reflex, and sensitivity disorder in the anogenital zone.

Rice. 8.15. Trophic ulcer on the foot with damage to the sciatic nerve.