Peripheral nervous system It consists of nerves coming from the dorsal and brain, which are responsible for the transfer of impulses from body organs and teams from nervous centers to control the vital activity of the whole body.

The nerve consists of many nerve fibers: axons, or continuations of neurons, neuroglia cells and other compounds responsible for their protection and maintenance of activity. Nervous threads are grouped into bundles covered with a connective tissue, each of which consists of various ligaments constituting the nerve and coated, in turn, an outer shell, called epideus.

Unlike arbitrary actions controlled by the brain, there are actions and movements that are automatically produced without the participation of higher nerve centers. Such actions are performed through a circle called a reflex arc consisting of receptors recognizing the pulse, nerve fibers transmitting the pulse in the spinal cord, where the response is produced, and nerve fibers transmitting commands to the organs performing them. For example, the knee reflex: the knee tendon is stretched, and the foot is instilled automatically. Other reflexes are more complex, and in their education is involved in the brain barrel: for example, the reflex of urination acting when the bladder, which, until a certain point, can be controlled, filled with urine.

12 pairs of nerveswhose kernels are located in the brain, depart from the brain or brain barrel: since the nerves come out on each side of the brain, they are called cerebral vapor, and although each nerve has its own name, they are denoted by Roman numbers from I to XII. These nerves are very important, since some of them, such as a visual or auditory nerve, receive sensory impulses, while others control the movement of the eyes or take part in digestive, cardiac and respiratory activities.

Couple I; Olfactory; Transmits the olfactory impulses from the nasal sinuses to the brain;
Couple II; Visual; Transfers visual pulses from the retina of the eye into the brain;
Couple III; Ovecake
Couple IV; Block; Takes part in the control of eye movements;
Pair v; Troinchik; Transfers sensory impulses on behalf of the brain and takes part in control over the chewing of food;
Pair Vi; Distribution; Takes part in the control of eye movements;
Pair VII; Facial; Controls the movements of the facial muscles and transfers the taste impulses from the language to the brain;
Pair VIII; Half-Ulitkov; Transmits auditory impulses and impulses that allow you to control the balance, from the inner ear in the brain;
Pair IX; Language; Controls the movements of the muscles of the pharynx and transfers the taste impulses from the language to the brain;
Pairs; Wandering; Controls the movements of the muscles of the pharynx and larynx and takes part in regulating the activities of the neck, chest (heart, breathing) and peritoneum (digestive system);
Pair xi; Dorsal; Controls the movements of the muscles of the neck, shoulders and larynx;
Pair XII; Sublingual; Controls the movement of the language.

Peripheral nerves include cerpeted and spinal nerves connecting the central nervous system (CNS) with peripheral organs and tissues. Spinal nerves are formed when merging ventral (front) and dorsal (rear) nerve roots at the place of their exit from the spine channel. Rear nerve roots form thickening - spinal ganglia (or rear root ganglia). The spinal nerves are relatively short - their length is less than 1 cm. Passing through the intervertebral hole, the spinal nerves are divided into ventral (front) and dorsal (rear) branches.

The rear branch ensures the innervation of muscles, straightening the spine, as well as the skin of the body in this area. The front branch innervates the muscles and the skin of the front of the body; In addition, sensitive fibers are departed from it to parietal pleura and parietal peritoneum.

The front branch also gives the beginning of the branches of the cervical, shoulder and lumbosacral nerve plexuses. Thus, the value of the concept of "branch" may vary depending on the context. (A detailed description of nervous plexuses is represented in chapters dedicated to anatomy.)

Breast spinal cord segment and nerve roots.
The arrows indicate the direction of the pulse. Green is designated sympathetic nervous fiber.

Peripheral neurons are partially located in the CNS. Motor (efferent) nerve fibers, innervating skeletal muscles, begin with multipolar a- and u-neurons located in the front rog of the gray substance. The structure of these neurons complies with the general principles characteristic of motioneons. More information is presented in a separate article on the site. The rear nerve roots originate from unipolar neurons whose bodies are located in spinal ganglia, and sensitive (afferent) central processes are included in the rear horn of the spinal cord.

The composition of the spinal nerve includes somatic efferent nerve fibers heading to the skeletal muscles of the body and limbs, and somatic afferent nerve fibers, conducting excitement from the skin, muscles and joints. In addition, visceral efferent and, in some cases, afferent vegetative nerve fibers are located in the spinal nerve.

The general principles of the inner structure of peripheral nerves are schematically shown in the figure below. Only on the structure of nerve fibers it is impossible to determine whether they are motor or sensitive.

Peripheral nerves are surrounded by an epideus - an outer layer consisting of dense uneven junction tissue and located around the beams of nerve fibers and blood vessels, blood supplying nerve. Nervous fibers of peripheral nerves can move from one bundle to another.

Each bundle of nerve fibers is covered with perinovel, presented by several distinctly distinguishable epithelial layers associated with dense slotted compounds. Separate Schwann cells are surrounded by an endoneurine formed by reticular collagen fibers.

Less than half of the nerve fibers are covered with myelin shell. Nemelined nerve fibers are located in deep folds of Schwann cells.

The concept of "nervous fiber" is usually used in describing the nervous impulse; In this context, it replaces the term "axon". Myelinated nerve fibers are axons surrounded by concentrically located layers (plates) of myelin, formed by plasma membranes of Schwann cells. Nevilinized nerve fibers are surrounded by separate nonmealinisygtsimi Schwann cells; The plasma membrane of these cells is a neurolem - at the same time covers several non-cellinized nerve fibers (axons). The structure formed by such akson and the Schwann cell was called "Gangle Remak".

The structure of the thoracic spinal nerve. Please note: the figure does not specify the sympathetic component.
KP - the end plate of the motor nerve on the muscle; Number is the nervous end of the muscular spindle; MN - multipolar.

but) Melina education. Schwann cells (lemmocytes) are representatives of neuroglial cells of the peripheral nervous system. These cells form a continuous chain along the peripheral nerve fibers. Each Schwann cellmiemiummiemizes a plot of a nervous fiber with a length of 0.3 to 1 mm. Modifying, Schvannovsky cells form satellite glyocytes in spinal and vegetative ganglia, and in the field of neuromuscular compounds - teloglia cells.

In the process of myelination, the axon simultaneously participates all of its Schwann cells. Each Schwann cell turns around the axon, forming the "duplicature" of the plasma membrane, -Saxon. Mesakson progulously shifts, winding on Akson. The consistently forming layers of the plasma membrane are located opposite each other and, "ousting" cytoplasm, form the main (large) and interpromate (fine) dense lines of myelin shell.

In the region of the end plots of myelinized axon segments on both sides of the interceptions of Ranviers (the gaps between the final sections of neighboring Schwann cells) are paranodal pockets.

Cross cut of the nervous trunk.
(A) Light microscopy. (B) electron microscopy. Myelination in the peripheral nervous system.
The arrows indicate the direction of winding the cytoplasm of the Schwann cell.

1. Melin accelerates the impulses. According to the axons of non-cellinized nerve fibers, the pulse is carried out continuously at a speed of about 2 m / s. Since myeline performs the function of an electrical insulator, an excitable membrane of myelinized nerve fibers is limited to the interceptions of Ranvier. In this connection, the excitation extends from one interception to another SaltaToatar - "jump-like", providing significantly greater speed of the nerve impulse, reaching 120 m / s values. The number of pulses conducted in a second is significantly higher in the myelinated nerve fibers compared to non-moving.

It should be noted that the larger the myelinized nerve fiber, the longer its interstitial segments, in connection with which the nerve impulses, "making big steps", spread with more speed. To describe the dependence between the size of the nervous fiber and the rate of pulses, you can use the "Rule of six": the speed of propagation of nerve pulses by fiber, the diameter of which is 10 nm (including the thickness of the myelin layer), is 60 m / s, and in a fiber with a diameter of 15 nm - 90 m / s, etc.

From the point of view of physiology, peripheral nerve fibers are classified by the velocity of nerve impulses, as well as on other criteria. Motor nerve fibers are divided into types A, B and C in accordance with the reduction of the rate of pulses. Sensitive nerve fibers are divided into group I-IV according to the same principle. However, in practice, these classifications are interchangeable: so, for example, non-relaxed sensitive nerve fibers are not related to type C, but to group IV.

Detailed information on diameters and places of localization of peripheral nerve fibers are presented in the tables below.

The electron microscopic image shows a myelinized peripheral nerve fiber and its surrounding Schwann cell. The figures below presents a group of non-mixed nerve fibers immersed in the cytoplasm of the Schwann cell and demonstrated a section of the interception of Ranvier Akson CNS.

b) The transition area of \u200b\u200bthe central nervous system into the peripheral nervous system. In the area of \u200b\u200bthe brain bridge and the spinal cord, the peripheral nerves are included in the transition zone between the central and peripheral nervous system. The processes of astrocytes from the central nervous system are immersed in epineurion of peripheral neurons roots and "intertwined" with Schwann cells. Astrocytes of non-cellinized fibers are immersed in space between axon and Schwann cells. Interceptions of Ranvier myelinized nerve fibers in the peripheral part are surrounded by myelin of Schvanna cells (demonstrating some transitional properties), and in the central part - myelin of oligodendrocytes.

in) Summary. The trunks of the spinal nerves pass in intervertebral holes. These structures are formed by connecting ventral (motor) and dorsal (sensitive) nerve roots and are divided into mixed ventral and dorsal branches. Nervous plexus limbs are represented by ventral branches.

Peripheral nerves are covered with an epineural connective tissue, a beam-like perioreural sheath and an endoneurry formed by collagen fibers and containing Schwann cells. Myelinated nerve fiber includes axon, myelin shell and cytoplasm of Schwann cell - neurolem. Myeline shells are formed by Svannowski cells and provide sealing pulses at a rate, directly proportional to the diameter of the nervous fiber.

a is myelinized nervous fiber. Ten layers of myelin surround the axon from the external to the inner Mesakson of the Schwannsky cell (indicated by arrows). The basal membrane surrounds the Schwann cell.
b - non-moving nerve fibers. Nine non-moving fibers are immersed in the cytoplasm of the Schwann cell. Mesaksons (some are indicated by arrows) are visualized with all axon immersion.
Two incompletely submerged axon (on top of the right) are covered with a basal membrane of the Schwann cell. The area of \u200b\u200binterception Ranvier CNS. Diving to the field of interception Ravlyye, the Mielinic shell narrows and ends, twisting in the field of paranodal pockets of the cytoplasm of Oligodendrocyte.
The length of the interception area of \u200b\u200bRanvier is about 10 nm; There is no basal membrane on this site.
Microtubule, neurofilaments and extended tanks of a smooth endoplasmic network (EPS) form longitudinal beams.
The transition area of \u200b\u200bthe central nervous system (CNS) into the peripheral nervous system (PNS).

In the human body there are several systems, including digestive, cardiovascular and muscle. Nervous is deserved separately - it makes the human body move, react to irritating factors, see and think.

The nervous system of man is a set of structures that performs the function of regulating absolutely all parts of the body, responsible for movement and sensitivity.

In contact with

Types of human nervous system

Before answering people who are interested in the question: "How the nervous system works," it is necessary to figure out what it actually consists and on which components it is accepted in medicine.

With the types of HC, not everything is so unambiguous - it is classified by several parameters:

• localization region;
• type of control;
• way to transfer information;
• functional accessory.

Localization area

The nervous system of man in the field of localization is happening central and peripheral. The first is represented by the head and bone marrow, and the second consists of nerves and the vegetative network.

CNS performs the regulation functions by all internal and external bodies. It makes them interact with each other. Peripheral is called the one that is due to the anatomical features is outside the spinal and brain.

How does the nervous system work? PNS responds to irritating factors, sending signals in the dorsal, and after and brain. After the central CNS organ processes them and again send signals to the PNS, which leads, for example, the muscles of the leg in motion.

Method of information transfer

On this principle allocate reflex and neurohumoral system. The first is a spinal cord, which without the participation of the head can react to stimuli.

Interesting!A person does not control the reflex function, since the spinal cord itself makes decisions. For example, when you touch the hot surface, your hand is immediately pulling away, and at the same time you did not even think of doing this movement - your reflexes worked.

Neurohumoral, to which the brain belongs, should initially process information, this process you can control. After that, the signals are sent to the PNS, which executes the commands of your brain center.

Functional accessory

Speaking about parts of the nervous system, it is impossible not to mention the vegetative, which in turn is divided into sympathetic, somatic and parasympathetic.

Vegetative system (VNS) is a department that is responsible for regulation of the work of lymph nodes, blood vessels, organs and glands (external and internal secretion).

The somatic system is a totality of nerves that are in the bones, muscles and skin. It is they who react to all environmental factors and send data to the cerebral center, and then execute its orders. Absolutely every movement of muscles is controlled by somatic nerves.

Interesting!The right-hand side of the nerves and muscles controls the left hemisphere, and the left is right.

The sympathetic system is responsible for emissions of adrenaline in blood, controls the work of the heart, lungs and flow of nutrients in all parts of the body. In addition, it regulates body saturation.

Parasympathetic is responsible for reducing the frequency of movements, also controls the work of the lungs, some glands, iris. An equally important task is to regulate digestion.

Type of control

Another hint to the question "how the nervous system" works can give a convenient classification by type of management. It is divided into higher and lower activities.

Higher activity controls the behavior in the environment. All intellectual and creative activities also relate to the highest.

Lower activity is the regulation of all functions within the human body. This type of activity makes all organism systems in a single whole.

The structure and functions of the NA

We have already figured out that all NSs should be divided into peripheral, central, vegetative and all of the above, but still need to say about their structure and functions.

Spinal cord

This body is located in the spinal canal And in essence, it is a sort of "rope" from nerves. It is divided into gray and white substance, where the first is completely covered with the second.

Interesting!In the context, it is noticeable that the gray substance is wetaped from the nerves in such a way that it reminds the butterfly. That is why it is often referred to as the "butterfly wings".

Total the spinal cord consists of 31 departmentEach of which is responsible for a separate group of nerves controlling certain muscles.

The spinal cord, as already mentioned, can work without the participation of the head - talking about reflexes that are not regulated. In the same turn, it is under the control of the body of the thinking and performs the conductive function.

Brain

This body is the least studied, many of its functions still cause many questions in circles. It is divided into five departments:

• big hemispheres (front brain);
• intermediate;
• oblong;
• rear;
• middle.

The first department is 4/5 of the entire mass of the body. It is responsible for vision, smell, movement, thinking, hearing, sensitivity. The oblong brain is an incredibly important center that regulates such processes like heartbeat, breathing, protective reflexes, allocation of gastric juice and others.

The average department controls such a function as. Intermediate plays a role in the formation of an emotional state. Also here are the centers responsible for thermoregulation and metabolism in the body.

Brain structure

Structure of the nerve

NA is a combination of billion specific cells. To figure out how the nervous system works, it is necessary to talk about its structure.

The nerve is a structure that consists of a certain amount of fibers. The same in turn consist of axons - they are the conductors of all impulses.

The number of fibers in one nerve can differ significantly. It usually is about one hundred, but in the human eye is more than 1.5 million fibers.

The axons themselves are covered with a special shell, which significantly increases the speed of the signal - this allows a person to respond to irritants almost instantly.

The nerves themselves are also different, and therefore they are classified for the following types:

• motor (transmit information from the central nervous system to the muscular system);
• skulls (here includes visual, olfactory and other types of nerves);
• sensitive (transmit information from PNS to the central nervous system);
• dorsal (located in and control the parts of the body);
• mixed (capable of transmitting information in two directions).

The structure of the nervous trunk

We have already figured out in such topics as "the kind of human nervous system" and "how the nervous system works", but there are many interesting facts aside, which are worth mentioning:

1. The number in our body is more than the number of people on the entire planet Earth.
2. The brain is about 90-100 billion neurons. If they all tie them into one line, it will reach about 1 thousand km.
3. The speed of movement of pulses reaches almost 300 km / h.
4. After the occurrence of puberty, the mass of the body of thinking every year decreases approximately one gram.
5. In men, the brain is approximately 1/12 more than female.
6. The largest body of thinking was recorded in a mentally ill.
7. CNS cells are practically not subject to recovery, and strong stress and unrest are able to seriously reduce their quantity.
8. Until now, science has not determined how much percent we use our chief mental body. The myths are known, which is not more than 1%, and geniuses are no more than 10%.
9. The size of the body of thinking is not does not affect mental activity. It was previously believed that men are smarter than fair sex representatives, but this statement was refuted at the end of the twentieth century.
10. Alcoholic beverages are very much suppressed by the function of synapses (the place of contact between the neurons), which is significantly slowing down thinking and motor processes.

We learned what kind of nervous system of a person is a complex combination of billion cells that interact with each other at a speed equal to the movement of the fastest cars in the world.

Among many types of cells, these are more difficult to restore everything, and some of their subspecies are not at all possible to restore. That is why they are beautifully protected by a skull and vertebate bones.

It is also interesting that the diseases of the NA are the least feeding treatment. Modern medicine is mostly only able to slow down the death of the cells, but stop this process is impossible. Many other types of cells using special preparations can be protected from destruction for many years - for example, liver cells. At this time, the cells of the epidermis (skin) are capable of regenerating in a matter of days or weeks to the previous state.

Nervous system - spinal cord (grade 8) - biology, preparation for the exam and OGE

Nervous human system. Building and function

Output

Absolutely any movement, every thought, look, sigh and heart blow - all this is controlled by a nerve network. It is responsible for the interaction of a person with the outside world and binds all other organs into a single whole - the body.

Ministry of Health of the Republic of Belarus

UO "Gomel State Medical University"

Department of Normal Physiology

Discussed at the meeting of the Department

Protocol number __________ 200__D

according to normal physiology for students of 2 courses

Subject: Physiology of neuron.

Time 90 minutes

Educational and educational purposes:

Submit information about the value of the nervous system in the body, structure and functions of peripheral nerve and synapses.

LITERATURE

2. Fundamentals of human physiology. Edited by B.I.kachenko. - St. Petersburg, 1994. - T.1. - pp. 43 - 53; 86 - 107.

3. Human physiology. Edited by R. Shmidt and TEVSA. - M., Mir. - 1996. - T.1. - P. 26 - 67.

5. General course of human and animal physiology. Edited by A.D. Zrosporchev. - M., Higher School.- 1991. - CN. 1. - p. 36 - 91.

Material

1. Multimedia presentation 26 slides.

Calculation of academic times

	List of learning issues	The amount of time allocated in minutes
	Building, nerve functions.
	Peripheral nervous system: brain and cereal nerves, nervous plexuses.
	Classification of nerve fibers.
	The laws of excitation by nerves.
	Parabitosis on the introduction.
	SINAPS: Building, classification.
	Mechanisms for transferring excitation in excitation and brake synapses.

Only 90 min

1. Building, nerve functions.

The value of the nervous tissue in the body is associated with the main properties of nerve cells (neurons, neurocytes) perceive the effect of the stimulus, switch to the excited state, to distribute the potentials of the action. The nervous system carries out the regulation of the activities of the tissues and organs, their relationship and communication of the body with the environment. The nervous fabric consists of neurons performing a specific function, and neuroglia, which plays auxiliary role that carries out the support, trophic, secretory, distinctive and protective function.

Nervous fibers (the processes of nerve cells covered with shells) perform a specialized function-carrying out nerve impulses. Nervous fibers form a nerve or a nerve trunk consisting of nerve fibers enclosed in a common connective tissue shell. Nervous fibers, conductive excitation from receptors in the central nervous system, are called afferent, and fibers conducting excitement from the CNS to the executive bodies are called efferent. Nerves consist of afferent and efferent fibers.

All nervous fibers for morphological attribute are divided into 2 main groups: myeline and non-ammous. They consist of a nervous cell process, which lies in the center of the fiber and is called the axial cylinder, and the shell formed by Schwann cells. On the cross section of the nerve, the cross sections of axial cylinders, nerve fibers and the covering of their glial shells are visible. Between the fibers in the composition of the trunk, thin interlayers of the connective tissue - endoneurry, beams of nerve fibers are covered with perinovel, which consists of cell layers and fibrils. The outer sheath of the nerve - epinery is a connecting fibrous fabric, rich in fat cells, macrophages, fibroblasts. The epineurion along the entire length of the nerve comes up a large number of blood vessels anastomosing among themselves.

Total characteristics of nerve cells

Neuron is a structural unit of the nervous system. Soma (body), dendrites and axon are distinguished in neuron. The structural functional unit of the nervous system is neuron, a clay cell and feeding blood vessels.

Niuron functions

Neuron has irritable, excitability, conductivity, lability. Neuron is able to generate, transmit, perceive the effect of potential, integrate impacts with the formation of an answer. Neurons possess background(without stimulation) and caused(after stimulus) activity.

Background activity can be:

Single - generation of single potentials of action (PD) at different intervals.

Pachkova - generation of a series of 2-10 PDs after 2-5 ms with more prolonged intervals between packs.

Group - series contain dozens of PD.

Activated activity arises:

At the time of the inclusion of "ON" incentive - neuron.

At the time of shutdown "Of" - neuron.

On the on and on the shutdown "ON - OF" - neurons.

Neurons can gradually change rest potential under the influence of the incentive.

Transmission function of neuron. Physiology of nerves. Classification of nerves.

On the structure of the nerves are divided into Moelinized (meal) and nonyelinated.

In the direction of information transfer (center - peripherals), the nerves are divided into afferent and efferent.

Efferent physiological effect are divided into:

Motor(innervate muscles).

Vessels (innervating vessels).

Secretory(innervate glands). Neurons have a trophic function - provide metabolism and preserving the structure of innervated tissue. In turn, neuron, lost innervation, also dies.

By the nature of the impact on the effector body, neurons are divided into launcher(translate the fabric from the state of physiological rest in the state of activity) and corrigatory(Change the activity of the functioning organ).

Peripheral nervous system. Spinal nerves

Structure of nerves

Development of spinal nerves

Education and branching of spinal nerves

The patterns of the stroke and branching of the nerves

The nervous system of a person is divided into central, peripheral and auto-

nomen parts. The peripheral part of the nervous system is a joint

the binding of the spinal and cranial nerves. It includes the nerves of ganglia and plexus, as well as sensitive and motor endings of nerves. Thus, the peripheral part of the nervous system combines all nervous formations that are outside the spinal and brain. Such an union is considered conditionally, since the efferent fibers that are part of the peripheral nerves are neuron process, the bodies of which are in the spinal cords and brain kernels. From a functional point of view, the peripheral part of the nervous system consists of conductors connecting the nerve centers with receptors and working bodies. Anatomy of peripheral nerves is of great importance for the clinic, as the basis for the diagnosis and treatment of diseases and damage to this unit of the nervous system.

Peripheral nerves consist of fibers that have a different structure and unequite

sound in functionality. Depending on the presence or absence of myelin fiber shell, myelin (meal) or non-ammous (cinema) (Fig. 1). The diameter of myelin nerve fibers are divided into thin (1-4 μm), medium (4-8 microns) and thick (more than 8 microns) (Fig. 2). There is a direct relationship between the thickness of the fiber and the speed of the nerve impulses. In thick myelin fibers, the speed of the nervous pulse is about 80-120 m / s, on average - 30-80 m / s, in thin - 10-30 m / s. Thick myeline fibers are predominantly motor and conductors of proprioceptive sensitivity, the average for the diameter of the fibers is carried out pulses of tactile and temperature sensitivity, and thin - pain. Mine-free fibers have a small diameter - 1-4 microns and pulses are carried out at a speed of 1-2 m / s (Fig. 3). They are the efferent fibers of the vegetative nervous system.

Thus, according to the composition of the fibers, it is possible to give a functional characteristic of the nerve. Among the nerves of the upper limb, the largest content of small and medium myelin and messenger fibers has the middle nerve, and their smallest number is part of the radiation nerve, the elbow nerve occupies the average position in this regard. Therefore, during damage to the median nerve, pain and vegetative disorders (disturbances, vascular changes, trophic disorders) are particularly expressed. The ratio in the nerves of myelin and messenger, thin and thick fibers individually changeable. For example, the number of thin and medium-sized myelin fibers in the middle nerve can be fluctuated from 11 to 45%.

Nerve fibers in the nerve trunk have a zigzag (sinusoidal) stroke that

protects them from abstratus and creates a reserve of elongation at 12-15% of their initial length at a young age and 7-8% - in the elderly (Fig. 4).

Nerves have a system of their own shells (Fig. 5). The outer shell, epinery, covers the nervous barrel from the outside, exciding it from the surrounding tissues, and consists of a loose unformed connective tissue. The loose connective tissue of the epinery performs all the gaps between the individual beams of nerve fibers.

In the epineuria in large quantities there are thick bunches of collagen fibers,

going predominantly longitudinally, cells of the fibroblastic row, histiocytes and fat cells. When studying the sedlicate nerve of a person and some animals, it has been established that epinery consists of longitudinal, oblique and circular collagen fibers having a zigzag-shaped stroke with a period of 37-41 microns and an amplitude of about 4 microns. Consequently, epinevion is a very dynamic structure that protects the nerve fibers when stretching and bending.

There is no consensus on the nature of the elastic fibers of the epinery. Some authors believe that there are no mature elastic fibers in the epineuria, but two kinds of fibers close to elastin are found: oxytalan and elauninov, which are parallel to the axis of the nervous barrel. Other researchers consider them elastic fibers. Fat fabric is an integral part of the epinery.

In the study of the cranial nerves and branches of the sacrum plexus of adults

it has been established that the thickness of the epinery ranges from 18-30 to 650 microns, but

more often is 70-430 microns.

Epidering is mainly a feed shell. In the epineuria undergo blood and

lymphatic vessels vasa Nervorum.which penetrate from here into the thickness of the nervous

barrel (Fig. 6).

The next shell, perhipurium, covers bundles of fibers, of which it consists of nerve it is mechanically the most durable. With light and electronic

microscopy has been established that perinery consists of several (7-15) layers of flat cells (peri-epitheral epithelium, neurothelium) with a thickness of 0.1 to 1.0 microns, between which separate fibroblasts and bunches of collagen fibers are located. It has been established that the bunches of collagen fibers have a dense arrangement in Perinouria and are oriented both in the longitudinal and concentric directions. Thin collagen fibers form a double spiral system in perinevuria. Moreover, the fibers form wavy networks in Perinneuria with a frequency of about 6 μm. In Pernenevuria, elaunin and oxytalan fibers were found, focused mainly longitudinally, and the first are mainly localized in its surface layer, and the second in the deep layer.

The thickness of the perinodule in nerves with the multiple structure is directly dependent on the magnitude of the beam covered. E-microscopy data indicate that perinery has a corrugated, folded organization. Perineuria is given great importance in the barrier function and ensuring the strength of the nerves. Perinoveuria, embedded in the thickness of the nervous beam, forms there connecting partitions with a thickness of 0.5-6.0 μm, which divide the bundle on the part. Such segmentation of beams is more often observed in late periods of ontogenesis.

Perinancial vagina of one nerve are connected to the perinancial vaginal

schams of neighboring nerves, and through these compounds there is a transition of the fibers from one nerve to another. If we take into account all these ties, then the peripheral nervous system of the upper or lower limb can be viewed as a complex system of interintently tubes, according to which the transition and exchange of nerve fibers are carried out both between beams within one nerve and between adjacent nerves. The inner shell, endoneurry, covers a thin connective tissue

case individual nerve fibers (Fig. 8). Cells and extracellular structures en-

ponviews are elongated and focused mainly in the course of nervous fibers. The amount of endoneurry inside the perinancial cases compared to the mass of the nerve fibers is small.

Nervous fibers are grouped into separate bundles of various caliber. Different authors have different determinations of the beam of nerve fibers depending on the position with which these beams are considered: from the point of view of neurosurgery and microsurgery or from the point of view of morphology. The classical determination of the nervous beam is a group of nerve fibers, bounded from other formations of nervous vehicle perinancial shell. And this definition is guided in the study of morphologists. However, with a microscopic examination of nerves, such conditions are often observed when several groups of nerve fibers adjacent to each other have not only their own perioreure shells, but also surrounded by

perineauge. These groups of nervous beams are often visible in a macroscopic study of the transverse slice of the nerve during neurosurgical intervention. And these bundles are most often described in clinical studies. Due to the different understanding of the structure of the beam occur in the literature of contradiction when describing the intravenous structure of the same nerves. In this regard, the Association of Nervous Punches, surrounded by a common peridemic, was called primary beams, and smaller, their components - secondary beams. On the cross-section of the nerve of the person, connective tissue shells (perinurium epineurion) occupy a significantly more space (67-84%) than beams of nerve fibers. It is shown that the number of connective tissue depends on the number of beams in the nerve.

It is much larger in nerves with a large number of small beams than in nerves with few large beams.

Depending on the structure of the beams, two extreme shapes of nerves are distinguished: low

voya and multiple. The first is characterized by a small amount of thick beams and a weak development of connections between them. The second consists of their sets of thin beams with well-developed inter partitions.

When the number of beams are small, bundles have significant sizes, and vice versa.

Low nerves differ relatively small thickness, the presence of non-

a large number of large beams, weak development of inter partitions, frequent axon location inside beams. Multicultural nerves are characterized by a greater thickness and consist of a large number of small beams, there are strongly developed inter partitions, axons are located in the endonorevia loose.

The thickness of the nerve does not reflect the amount of fibers contained in it, and there are no patterns of the location of the fibers on the transverse cut of the nerve. However, it was established that in the center of the nerve bundles always thinner, on the periphery - on the contrary. The beam thickness does not characterize the amount of fibers enclosed in it.

In the structure of the nerves, a clearly pronounced asymmetry is installed, that is, unequal

the structure of nerve trunks on the right and left sides of the body. For example, a diaphragmal

no nerve has a larger amount of beams to the left than the right, and the wandering nerve -

on the contrary. One person has the difference in the amount of beams between the right and left median nerves can vary from 0 to 13, but more often is 1-5 beams. The difference in the amount of beams between the median nerves of different people is equal to 14-29 and increases with age. At the elbow nerve at the same person, the difference between the right and left sides in the amount of beams can vary from 0 to 12, but more often it is also 1-5 beams. The difference in the amount of beams between the nerves of different people reaches 13-22.

The difference between individual subjects in the amount of nerve fibers varies in

the middle nerve from 9442 to 21371, in the elbow nerve - from 9542 to 12228. At the same person, the difference between the right and left side varies in the middle nerve from 99 to 5139, in the elbow nerve - from 90 to 4346 fibers.

Sources of blood supply to nerves are neighboring nearby arteries and their

branches (Fig. 9). To the nerve, several arterial branches are usually suitable, and

the rulars between the incoming vessels are varied in large nerves from 2-3 to 6-7 cm, and in the seeded nerve - up to 7-9 cm. In addition, such large nerves, as the middle and sedanistic, have their own accompanying arteries. In the nerves having a large amount of beams, there is a lot of blood vessels in the epineuria, and they have a relatively small caliber. On the contrary, in nerves with a small amount of bunches of the vessels of single, but significantly larger. Arteries that feed the nerve in the epineuria T-shaped are divided into ascending and downward branches. Inside the nerves arteries are divided to the branches of the 6th order. The vessels of all orders anatomize among themselves, forming intravenous networks. These vessels play a significant role in the development of collateral blood circulation when the large arteries are turned off. Each artery nerve is accompanied by two veins.

The lymphatic vessels of the nerves are in the epineuria. In perinovevuria between its layers, lymphatic slots are formed communicating with the lymphatic vessels of epinery and epinery lymphatic slots. Thus, in the course of nerves, infection can be distributed. Of large nervous trunks, several lymphatic vessels usually come out.

The shells of the nerves are innervated by branches that are separated from this nerve. The nerves of the nerves are mainly sympathetic and the functions are vessels.