Gray matter of the nervous system. Nervous system Gray matter covers

CNS (Spinal cord and brain. Formed by gray and white matter)

Peripheral (nerves, ganglia)

Nervous system

Somatic

Vegetative

Sympathetic

Parasympathetic

Gray matter is a collection of bodies of neurons. It is organized in the form of nuclei (local formations, centers of regulation) and cortex (a continuous layer of gray matter, only in the cerebellum and cerebral hemispheres - a complex structure, performs complex diverse functions).

white matter - this is a cluster of myelinated processes of neurons (fibers). Performs a conductive function.

Nerves - an accumulation of nerve fibers, each nerve is an organ. Performs a conductive function.

spinal nerves – 31 couples mixed type(sensory and motor fibers). Accumulation of bodies of sensitive neurons.

cranial nerves - 12 pairs (either sensitive, or motor, or mixed type).

Nerves (ganglia) - formed by the bodies of neurons on the periphery.

Autonomic nerves - accumulation of bodies of the second motor vegetative neurons.

somatic nervous system - the department innervates (supplies) the nerves. Responsible for the activity of skeletal muscles.

autonomic nervous system - innervates (ends) on the smooth muscles of the internal organs or glands.

Spinal cord

Spinal cord- an organ of the central nervous system of vertebrates located in the spinal canal. It is generally accepted that the border between the spinal cord and the brain passes at the level of the intersection of the pyramidal fibers (although this border is very arbitrary). Inside the spinal cord there is a cavity called the central canal. The spinal cord is protected by the pia mater, arachnoid and dura mater. The spaces between the membranes and the spinal canal are filled with cerebrospinal fluid. The space between the outer hard shell and the bone of the vertebrae is called the epidural and is filled with fat and venous network.

White matter is a complex system of various lengths and thicknesses of myelinated and partly unmyelinated nerve fibers and supporting nervous tissue - neuroglia, as well as blood vessels surrounded by a small amount of connective tissue. Nerve fibers in the white matter are collected in bundles.

The white matter of one half of the spinal cord is connected with the white matter of the other half by a very thin white commissure running transversely in front of the central canal.

The sulci of the spinal cord, with the exception of the posterior intermediate sulcus, delimit the white matter of each half into three cords of the spinal cord. Distinguish:

anterior funiculus - part of the white matter, bounded by the anterior median fissure and the anterolateral groove, or the exit line of the anterior roots of the spinal nerves;

lateral cord - between the anterolateral and posterolateral grooves;

posterior funiculus - between the posterolateral and posterior median sulci.

In the upper half of the thoracic part and in the cervical part of the spinal cord, the posterior intermediate sulcus divides the posterior funiculus into two bundles: a thinner, medial, so-called thin bundle lying inside, and a more powerful lateral wedge-shaped bundle. Below the wedge-shaped bundle is absent. The cords of the spinal cord continue into the initial section of the brain - the medulla oblongata.

As part of the white matter of the spinal cord, there are projection, constituting afferent and efferent pathways, as well as associative fibers. The latter carry out connections between segments of the spinal cord and form anterior, lateral and posterior bundles of their own, which are adjacent to the gray matter of the spinal cord, surrounding it from all sides. These bundles include:

dorsolateral pathway - a small bundle of fibers located between the top of the posterior gray column and the surface of the spinal cord in close proximity to the posterior root

septal-marginal bundle - a thin bundle of descending fibers, closely adjacent to the posterior median fissure, can be traced only in the lower thoracic and lumbar segments of the spinal cord

interfascicular bundle - formed by descending fibers located in the medial part of the wedge-shaped bundle, can be traced in the cervical and upper thoracic segments.

3. Gray and white matter of the cerebral hemispheres. Localization of functions in the cerebral cortex.

White matter of the hemispheres

The entire space between the gray matter of the cerebral cortex and the basal ganglia is occupied by white matter. The white matter of the hemispheres is formed by nerve fibers that connect the cortex of one gyrus with the cortex of other gyri of its own and opposite hemispheres, as well as with the underlying formations. Topographically, four parts are distinguished in the white matter, not sharply delimited from each other: 1) white matter in the gyri between the furrows; 2) an area of ​​​​white matter in the outer parts of the hemisphere semi-oval center (centrum semiovale); 3) radiant crown (corona radiata), formed by radially diverging fibers entering the inner capsule (capsula interna) and leaving it; 4) the central substance of the corpus callosum (corpus callo sum), the internal capsule and long associative fibers.

The nerve fibers of the white matter are divided into associative, commissural and projection.

Associative fibers connect different parts of the cortex of the same hemisphere. They are divided into short and long. Short fibers connect adjacent convolutions in the form of arcuate bundles. Long associative fibers connect areas of the cortex that are more distant from each other.

The commissural fibers that make up the cerebral commissures, or adhesions, connect not only symmetrical points, but also the cortex belonging to different lobes of opposite hemispheres.

Most of the commissural fibers are part of the corpus callosum, which connects the parts of both hemispheres belonging to the neencephalon. Two cerebral commissures, commissura anterior and commissura fornicis, are much smaller in size to the olfactory brain of the rhinencephalon and connect: commissura anterior - olfactory lobes and both parahippocampal gyri, commissura fornicis - hippocampus.

Projection fibers connect the cerebral cortex with the underlying formations, and through them with the periphery.

These fibers are divided into centripetal (ascending, corticopetal, afferent), conducting excitation towards the cortex, and centrifugal (descending, corticofugal, efferent). Projection fibers in the white matter of the hemisphere closer to the cortex form a radiant crown, and then the main part of them converges into an internal capsule, which is a layer of white matter between the lentiform nucleus (nucleus lentiformis) on the one hand, and the caudate nucleus (nucleus caudatus) and the thalamus ( thalamus) - on the other. On the frontal section of the brain, the internal capsule looks like an oblique white stripe continuing into the brain stem. In the internal capsule, the anterior leg (crus anterius) is distinguished, - between the caudate nucleus and the anterior half of the inner surface of the lentiform nucleus, the posterior leg (crus posterius), - between the thalamus and the posterior half of the lentiform nucleus and knee (genu), lying at the place of inflection between both parts of the internal capsule. Projection fibers along their length can be divided into the following three systems, starting with the longest:

1. Tractus corticospinalis (pyramidalis) conducts motor volitional impulses to the muscles of the trunk and limbs.

2. Tractus corticonuclearis - pathways to the motor nuclei of the cranial nerves. Since all motor fibers are collected in a small space in the internal capsule (the knee and the anterior two-thirds of its posterior leg), if they are damaged in this place, unilateral paralysis of the opposite side of the body is observed.

3. Tractus corticopontini - paths from the cerebral cortex to the nuclei of the bridge. Using these pathways, the cerebral cortex has an inhibitory and regulatory effect on the activity of the cerebellum.

4. Fibrae thalamocorticalis et corticothalamici - fibers from the thalamus to the cortex and back from the cortex to the thalamus.

Gray matter of the hemispheres

The surface of the hemisphere, the pallium, is formed by a uniform layer of gray matter 1.3–4.5 mm thick containing nerve cells. The surface of the cloak has a very complex pattern, consisting of furrows alternating with each other in various directions and ridges between them, called gyri. The size and shape of the furrows are subject to significant individual fluctuations, as a result of which not only the brain various people, but even the hemispheres of the same individual are not quite similar in furrow pattern.

Deep permanent furrows are used to divide each hemisphere into large areas called lobes, lobi; the latter, in turn, are divided into lobules and convolutions. There are five lobes of the hemisphere: frontal (lobus frontalis), parietal (lobus parietalis), temporal (lobus temporalis), occipital (lobus occipitalis) and a lobule hidden at the bottom of the lateral groove, the so-called island (insula).

The upper lateral surface of the hemisphere is delimited into lobes by means of three furrows: the lateral, central and upper end of the parietal-occipital sulcus. The lateral groove (sulcus cerebri lateralis) begins on the basal surface of the hemisphere from the lateral fossa and then passes to the upper lateral surface. The central sulcus (sulcus cenrtalis) begins at the upper edge of the hemisphere and goes forward and downward. The area of ​​the hemisphere located in front of the central sulcus. Refers to the frontal lobe; the part of the cerebral surface lying behind the central sulcus is the parietal lobe. The posterior border of the parietal lobe is the end of the parietal-occipital sulcus (sulcus parietooccipitalis), located on the medial surface of the hemisphere.

Each lobe consists of a series of convolutions, called in some places lobules, which are limited to the furrows of the cerebral surface.

Frontal lobe. In the posterior part of the outer surface of this lobe, the sulcus precentralis runs almost parallel to the direction of the sulcus centralis. Two furrows pass from it in the longitudinal direction: sulcus frontalis superior et sulcus fronta lis inferior. Due to this, the frontal lobe is divided into four convolutions. The vertical gyrus, gyrus precentralis, is located between the central and precentral sulci. The horizontal convolutions of the frontal lobe are: upper frontal (gyrus frontalis superior), middle frontal (gyrus frontalis medius) and lower frontal (gyrus frontalis inferior).

Parietal lobe. On it, approximately parallel to the central sulcus, is the sulcus postcentralis, which usually merges with the sulcus intraparietalis, which runs in a horizontal direction. Depending on the location of these furrows, the parietal lobe is divided into three convolutions. The vertical gyrus, gyrus postcentralis, runs behind the central sulcus in the same direction as the precentral gyrus. Above between the parietal sulcus is placed the superior parietal gyrus, or lobule (lobulus parietalis superior), below - lobulus parieta lis inferior.

The temporal share. The lateral surface of this lobe has three longitudinal convolutions, separated from each other by sulcus temporalis superior and sulcus temporalis inferior. Gyrus tempora lis medius extends between the upper and lower temporal sulci. Below it passes gyrus temporalis inferior.

Occipital lobe. 0 Furrows on the lateral surface of this lobe are changeable and unstable. Of these, a transverse sulcus occipitalis transversus is distinguished, which usually connects to the end of the interparietal sulcus.

Island. This slice is in the shape of a triangle. The surface of the island is covered with short convolutions.

The lower surface of the hemisphere in that part of it, which lies anterior to the lateral fossa, belongs to the frontal lobe.

Here, sulcus olfactorius runs parallel to the medial edge of the hemisphere. On the posterior part of the basal surface of the hemisphere, two furrows are visible: sulcus occipitotemporalis, passing in the direction from the occipital pole to the temporal and limiting the gyrus occipitotemporalis lateralis, and running parallel to it sulcus collateralis. Between them is gyrus occi pitotemporalis medialis. Medially from the collateral sulcus there are two convolutions: between the posterior part of this sulcus and the sulcus calcarinus lies the gyrus lingualis; between the anterior part of this furrow and the deep sulcus hippocampi lies the gyrus pa rahippocampalis. This gyrus, adjacent to the brain stem, is already on the medial surface of the hemisphere.

On the medial surface of the hemisphere there is a corpus callosum groove (sulcus corpori callosi), running directly above the corpus callosum and continuing with its posterior end into the deep sulcus hippocampi, which goes forward and downward. Parallel to and above this groove, it runs along the 5th medial surface of the sulcus cinguli hemisphere. Paracentral lobule (lobulus paracentralis) is a small area above the lingual groove. Behind the paracentral lobule is a quadrangular surface (the so-called precuneus). It belongs to the parietal lobe. Behind the prewedge lies a separate section of the cortex related to the occipital lobe - a wedge (cuneus). Between the lingual groove and the groove of the corpus callosum stretches the cingulate gyrus (gy rus cinguli), which, through the isthmus (isthmus), continues into the parahippocampal gyrus, ending in a hook (uncus). Gyrus cinguli, isthmus and gyrus parahippocam palis together form a vaulted gyrus (gyrus fornicatus), which describes an almost complete circle, open only from below and in front. The vaulted gyrus is not related to any of the lobes of the cloak. It belongs to the limbic region. The limbic region is part of the neocortex of the cerebral hemispheres, occupying the cingulate and parahippocampal gyrus; part of the limbic system. Expanding the edge of the sulcus hippocampi, one can see a narrow jagged gray strip, which is a rudimentary gyrus dentatus gyrus.

Brodmann fields In the cerebral cortex, zones are distinguished - Brodmann fields (German physiologist). 1st zone - motor - represented by the central gyrus and the frontal zone in front of it - 4, 6, 8, 9 Brodmann fields. When it is irritated - various motor reactions; with its destruction - violations of motor functions: adynamia, paresis, paralysis (respectively - weakening, a sharp decrease, disappearance). In the 50s of the twentieth century. found that different muscle groups are represented differently in the motor zone. The muscles of the lower limb - in the upper section of the 1st zone. muscles upper limb and heads - in the lower part of the 1st zone. The largest area is occupied by the projection of mimic muscles, muscles of the tongue and small muscles of the hand. 2nd zone - sensitive - sections of the cerebral cortex posterior to the central sulcus (1, 2, 3, 4, 5, 7 Brodmann fields). When this zone is irritated, sensations arise, when it is destroyed, loss of skin, proprio-, interosensitivity occurs. Hypothesia - decreased sensitivity, anesthesia - loss of sensitivity, paresthesia - unusual sensations (goosebumps). The upper sections of the zone - the skin of the lower extremities, genitals is represented. In the lower sections - the skin of the upper limbs, head, mouth. 1st and 2nd zones are closely related to each other functionally. There are many afferent neurons in the motor area that receive impulses from proprioreceptors - this is motosensory zones. In the sensitive zone, there are many motor elements - these are sensorimotor zones - are responsible for the occurrence pain.3rd zone - visual zone - occipital region of the cerebral cortex (17, 18, 19 Brodmann fields). With the destruction of the 17th field - loss of visual sensations (cortical blindness). Different parts of the retina are not equally projected into the 17th Brodmann field and have a different location; when the point destruction of the 17th field, the vision of the environment falls out, which is projected onto the corresponding parts of the retina. With the defeat of the 18th field of Brodmann, the functions associated with the recognition of a visual image suffer and the perception of writing is disturbed. With the defeat of the 19th field of Brodmann, various visual hallucinations occur, visual memory and other visual functions suffer. 4th - auditory zone - temporal region of the cerebral cortex (22, 41, 42 Brodmann fields). If 42 fields are damaged, the function of sound recognition is impaired. When the 22nd field is destroyed, auditory hallucinations, impaired auditory orienting reactions, and musical deafness occur. With the destruction of 41 fields - cortical deafness. 5th zone - olfactory - located in the piriform gyrus (11 Brodmann field). 6th zone - taste - 43 Brodman field. 7th zone - motor speech zone (according to Jackson - the center of speech) - in most people (right-handed) is located in the left hemisphere. This zone consists of 3 departments. Broca's speech motor center - located in the lower part of the frontal gyri - this is the motor center of the muscles of the tongue. With the defeat of this area - motor aphasia. Wernicke Sensory Center - located in the temporal zone - associated with the perception of oral speech. With a lesion, sensory aphasia occurs - a person does not perceive oral speech, pronunciation suffers, as the perception of one's own speech is disturbed. Center for Written Speech Reception - located in the visual zone of the cerebral cortex - 18 Brodmann's field similar centers, but less developed, are also in the right hemisphere, the degree of their development depends on the blood supply. If the right hemisphere is damaged in a left-handed person, the speech function suffers to a lesser extent. If the left hemisphere is damaged in children, then the right hemisphere takes over its function. In adults, the ability of the right hemisphere to reproduce speech functions is lost. In total, they distinguish (according to Brodman) - 53 fields.

Pavlov's idea of ​​the localization of functions in the cerebral cortex Cortex is a set of brain departments, analyzers. Different parts of the cerebral cortex can simultaneously perform both afferent and efferent functions. Brain section of the analyzer - consists of a nucleus (central part) and scattered nerve cells. The nucleus is a set of highly developed neurons located in a strictly defined area of ​​the cerebral cortex. The defeat of the kernel leads to the loss of a certain function. The core of the visual analyzer is located in the occipital region, the brain section of the auditory analyzer is located in the temporal region. Scattered nerve cells - less differentiated neurons scattered throughout the cortex. They have more primitive sensations. The largest accumulations of these cells in the parietal region. These cells are necessary because sensations arise in them, which ensure the performance of the function when the nucleus is damaged. Normally, these cells provide communication between various sensory systems.

Modern ideas about the localization of function in the cerebral cortex There are projection zones in the cerebral cortex. Primary projection area - occupies the central part of the core of the brain analyzer. This is a collection of the most differentiated neurons, in which the highest analysis and synthesis of information takes place, clear and complex sensations arise there. Impulses are approached by these neurons along a specific pathway for transmitting impulses in the cerebral cortex (the spinothalamic pathway). Secondary projection area - located around the primary, is part of the core of the brain section of the analyzer and receives impulses from the primary projection zone. Provides complex perception. With the defeat of this zone, a complex dysfunction occurs. Tertiary projection zone - associative - these are polymodal neurons scattered throughout the cerebral cortex. They receive impulses from the associative nuclei of the thalamus and converge impulses of various modalities. Provides links between different analyzers and play a role in the formation of conditioned reflexes.

All structures of the nervous system are made up of neurons that form the gray and white matter of brain tissue.

The distribution of these structures depends on the functionality of the department to which they belong: for example, the gray matter of the brain covers the white substance, while in the dorsal region, the nuclei, consisting of gray neurons, are located inside the brain canal formed by the white component.

The human nervous system has a complex structure. Conventionally, experts distinguish the peripheral and central nervous system of a person.

The human central nervous system includes all parts of the brain (final, middle, oblong, intermediate, cerebellum), as well as the spinal cord. These components control the work of all body systems, connect them with each other and ensure their coordinated work in response to extraneous influences.

Functional features of the central nervous system:

• The human brain is located in the cranium and performs a controlling role: it participates in the processing of information received from the environment and regulates the vital activity of all systems. human body, is a kind of steering wheel.
• The main function of the spinal CNS is to transmit information from nerve centers located in other parts of the body to the brain. Also, with its support, motor reactions to external stimuli are performed (using reflexes).

The peripheral NS includes all branches of the spinal cord and brain that are outside the CNS, or, in other words, on the periphery. It includes cranial and spinal nerves, as well as autonomic nerve fibers that connect the structures of the central nervous system with other parts of the human body. With its help, there is an unconscious (at the level of reflexes) control of the vital functions of certain organs, whether it be a heartbeat or automatic muscle contraction in response to external stimuli (for example, blinking).

This part of the nervous system is especially vulnerable to the effects of various toxins or mechanical damage, since it does not have protection in the form of bone tissue or a special barrier separating blood and its components.

Peripheral NS include:

• Vegetative or autonomous NS. It is controlled by the human subconscious, controls the performance of vital body functions. The main task of this part of the NS is the regulation of the internal environment of the body, through the circulatory, endocrine systems, as well as various endocrine and external secretion glands. Anatomically, sympathetic, parasympathetic and metasympathetic NS are distinguished in it. In this case, the centers or vegetative nuclei, consisting of the gray brain component, are located in the spinal and head sections of the CNS, and the latter are clusters of neurons located in the walls Bladder, gastrointestinal tract and other organs.
• Somatic NS. Responsible for the motor function of a person - with its help, afferent (incoming) signals are transmitted to the neurons of the central nervous system, from where, after processing, information is received through the efferent (descending motor) fibers to the limbs and organs human body to reproduce the corresponding movement. Its neurons have a special structure that allows you to transmit data over long distances. So, most often, the body of a neuron is located in the immediate vicinity of the CNS or enters it, but at the same time its axon stretches further, reaching the surface of the skin or muscles as a result. Through this part of the National Assembly, various protective reflexes are performed, which are performed at the subconscious level. This feature is achieved by the presence of reflex arcs that allow you to perform an action without the participation of the main center, since in this case the nerve fibers connect the dorsal CNS with a part of the body directly. At the same time, the final point of information perception is the cerebral cortex, where memories of all performed actions remain. Thus, the somatic NS is involved in learning, protection and the ability to process information received from the environment.
• Some experts refer to the peripheral NS as the human sensory nervous system. It includes several groups of neurons located on the periphery of the central nervous system, which are responsible for the perception of information from the environment through the organs of hearing, sight, touch, taste and smell. Responsible for the physical perception of such concepts as temperature, pressure, sound.

As mentioned earlier, the structures of the human nervous system are represented by a white and gray substance, while each of them has its own structure and contains different types of nerve cells that differ in appearance and functionality.

Thus, the white matter mainly performs a conductive function and transmits nerve impulses from one part of the medulla to another. This feature is due to the structure of the neurons of this structure, the bulk of which are long processes or axons covered with myelin, which has a high electrical impulse conductivity (of the order of 100 m/s).

Axons of neurons can be conditionally divided into 2 main groups:

1. Long (intracortical), connect distant areas, are located in the depths of the medulla.
2. Short processes that connect the gray cells of the cortex and nearby structures of the white matter have a second name - subcortical.

Also, depending on the location and functionality of the white matter nerve cell fiber, it is customary to distinguish the following groups:

• Associative. They differ in size: they can be both long and short and perform various tasks, but at the same time they are concentrated in one of the hemispheres. Long axons are responsible for the connection of distant convolutions, and short axons unite nearby structures.
• Commissural. They connect 2 hemispheres with each other and ensure their coordinated work, located in opposite parts. Similar axons can be considered in the anatomical study of this organ, since they consist of the anterior commissure, the corpus callosum, and the commissure of the fornix. Projection axons connect the cortex with other centers of the central nervous system, including the spinal cord. the thalamus with the cortex, the second - the cortex with the nuclei of the bridge, and the third conduct impulses, due to which the command and control of certain limbs is performed.

There are 2 types of such fibers, which differ in the direction of the transmitted information:

1. Afferent. According to them, information comes from the underlying structures of the brain, systems of organs and tissues to the cortex and subcortical structures that process the information received.
2. Efferitic. Conduct a response impulse from the centers of higher mental activity to controlled structures.

The opposite of the white medulla is the gray component, which, like its predecessor, consists of a cluster of neurons - with their help, all the functions of a person's higher nervous activity are performed.

Its main part is located on the surface of the white brain component located in the head, and makes up the bark, which has a conditionally gray color. It also lies in the depths of the brain and along the entire length of the spinal cord in the form of nuclei. The composition of the gray matter includes several groups of nerve cells, their dendrites and axons, as well as glial tissues that perform an auxiliary function.

Branched processes of neurons or dendrites, through synapses, receive and transmit information from the axons of neighboring cells to their own. The quality of the impulse depends on the density of their branching - the more developed the branches of the main fiber and the more extensive the network of synapses, the more data from neighboring cells will come to the cell nucleus.

Since neurons and, accordingly, the nuclei of gray matter cells are located close to each other, they do not require long axons, while the main flow of information is transmitted through the dendritic-synaptic connection of nearby cells. For the same reason, their axons do not need a myelin sheath.

Separate accumulations of gray matter are called nuclei, each of which controls the performance of a certain vital function of the body, while they can be divided into 2 large groups: those related to the central nervous system and those responsible for the peripheral nervous system.

The anatomical structure of gray matter neurons in all parts of the CNS has a similar structure and approximately the same composition. Therefore, the regularity of the arrangement of neurons in the final section is no different from the combination of these elements in other structures.

Where is the gray matter

The gray matter of the brain is represented mainly by the accumulation a large number neurons with unmyelinated axons woven into glial tissues, their dendrites and blood capillaries that provide their metabolism.

The largest accumulation of gray neurons forms the cerebral cortex, which covers the surface of the terminal section. The thickness of this structure is no more than 0.5 cm throughout, but it occupies more than 40% of the volume of the telencephalon, and its surface is many times greater than the plane of the cerebral hemispheres. This characteristic is due to the presence of wrinkles and convolutions, which contain up to 2/3 of the area of ​​the entire cortex.

Also, accumulations of gray matter in the brain form special nerve centers or nuclei that have characteristic shape and its functional purpose. A feature of the structure of this structure is that the concept of "nucleus" means a paired or dispersed formation of neurons from cells that do not have a myelin sheath.

There are a large number of nuclei of the nervous system, which, for a general concept and ease of perception, are usually identified according to the operation they perform, as well as their appearance. Such a distribution does not always correctly reflect reality, since the brain is a poorly understood structure of the central nervous system and sometimes scientists are mistaken.

The main accumulation of nuclei is located inside the trunk, for example, in the thalamus or hypothalamus. At the same time, the basal ganglia are located in the anterior section, which to some extent affect the emotional behavior of a person, participate in maintaining muscle tone.

The gray matter of the cerebellum, like the cortex of the final section of the brain, covers the hemispheres and the vermis along the periphery. Also, its individual ones form paired nuclei in the depths of the body of this rudiment.

Anatomically, the following types of nuclei are distinguished in it:

• Serrated. It is located in the lower part of the white matter of the cerebellum, its pathways are responsible for the motor function of skeletal muscles, as well as for the visuo-spatial orientation of a person in space.
• Spherical and corky. They process information received from the worm, and also receive afferent signals from parts of the brain responsible for somatosensory, auditory and visual data.
• The core of the tent. It is located in the tent of the cerebellar vermis and receives information about the position of the human body in space according to the data received from the sense organs and the vestibular apparatus.

A characteristic feature of the structure of the spinal cord is that the gray substance in the form of nuclei is located inside the white component, but at the same time it is an integral part of it. Such an arrangement can be seen in most detail when studying the dorsal CNS in a transverse section, where a clear transition of gray matter to white from the center to the periphery will be clearly visible.

Where is white matter located

The white matter of the brain begins to form by 6 months of intrauterine development of a person, while its formation does not stop over the next years of life. This feature allows the body to train and accumulate the experience gained.

In itself, white matter is the opposite of gray and is a dense network of branches of neurons that transmit information from the cerebral cortex to the underlying nerve centers of the spinal cord and brain. At the same time, the functioning of the connection is affected by the quantity and quality of the formed neural pathways: the denser and stronger the connection between the structures, the more developed and talented the individual is.

The largest accumulation of white matter is in the cranium and is represented by large lobes. It is understandable: all the control centers of the body are located in the brain, and in its structures the formation and implementation of higher mental tasks take place, the presence of which distinguishes a person from the rest of the animal world. At the same time, the white matter, in addition to the main one, also performs a protective function: in appearance and physical characteristics, it is a gelatinous fat-like mass, which plays the role of a shock absorber for the underlying structures.

Also, the white matter forms a peripheral meningeal membrane for the gray matter of the spinal cord - like the head section of the CNS, it contains all types of fibers (commissural, associative and projection), with a characteristic myelin coloration, which are collected in special bundles that provide a connection between the spinal cord and other parts peripheral and central NS.

What is the gray matter of the brain responsible for?

Work on the study of the brain as a controlling organ began in the 18th century and continues to this day. Perhaps this process would have gone much faster if there had not been a ban on the anatomical study of brain tissues and the dissection of the body of a deceased person for a long time. The situation is also complicated by the fact that the brain is a rather inaccessible organ, which is reliably protected from the outside by the bones of the skull and a large number of membranes, damage to which can negatively affect the test subject.

So, the human brain includes several functional clusters of gray matter neurons, whether it be its cortex or nuclei, which are responsible for performing individual movements or controlling the activity of some vital body systems.

The cerebral cortex is a relatively young structure that began to form in the process of human evolutionary development. Its presence and degree of development is a hallmark of the human brain, since in most mammals the gray matter of the cortex is limited in size and not so functional.

The main function of the gray matter of the cerebral cortex is the fulfillment of higher psychiatric tasks that the individual sets for himself in the process of learning new skills, while experience can be obtained from other sources or the environment. Also, the expression of the work of the cerebral cortex is the sound reproduction of speech and its internal manifestation, which is still popularly denoted by the concept of “to oneself”.

Also, gray matter forms nuclei and small plates, which are also present in other parts of the brain.

The medulla oblongata, as a functional continuation of the spinal region, combines the characteristic features of the structure of both parts of the CNS. As well as the dorsal, it includes a large number of conductive fibers, the main task of which is to connect the final section with the dorsal. At the same time, the gray matter of the medulla oblongata no longer has a characteristic continuous structure, as in the cerebral cortex, but lies in the form of nuclei.

This department, as well as the entire central nervous system, regulates the implementation of physiological processes on which human life depends. These include the following operations: breathing, heartbeat, excretion, digestion, as well as protective reflex movements (such as blinking or sneezing) and muscle tone. Nerve paths and centers pass through it, which are responsible for the coordination and spatial position of the body in the environment through the nuclei of the vestibular apparatus.

A characteristic feature of the location and structure of gray matter in the middle section of the brain is that it combines the structural features of the oblong and terminal sections, while paired accumulations of gray matter form nuclei, and separately scattered neurons form a central near-water structure and the so-called black substance.

The anatomical structure of the nuclei and this department does not differ from the structure of this structure in the medulla oblongata. The main task of these centers is the perception of information from the environment through the organs of hearing, vision, smell, and also participate in the performance of some conditioned reflexes, for example, turning the head towards a loud sound or bright light.

Other structures of the middle section require special attention: the central gray matter and the substantia nigra. They have a number of features due to their structure and purpose.

A layer of substantia nigra conditionally separates the brain stem from the tire and regulates the motor function of the limbs. It is noticed that with the defeat of this component of the National Assembly, the patient develops Parkinson's disease, tremor of the limbs, and there is also a decrease in motor skills.

The central near-aqueductal gray matter is a sparse, scattered collection of unmyelinated neurons surrounding the aqueduct. It serves as a conductor and accumulator of information from the underlying structures (the reticular formation, the nuclei of the vestibular apparatus, the hypothalamus, etc.), and also participates in the formation of pain sensations of aggressive behavior and controls the sexual behavior of a person.

What is white matter responsible for?

As mentioned earlier, the white matter of the brain performs several tasks: first of all, it is a link between the gray matter of the cortex and other functional clusters of neurons located in deep structures.

Other functions of the white matter of the brain are also known - it acts as a link between the cerebral hemispheres through the corpus callosum, and also ensures the interaction of remote areas of the cortex with other parts of the nervous system, including the spinal cord, using specific fibers.

Its main feature and distinguishing feature is that the white matter is formed by an accumulation of long nerve processes or fibers covered with a myelin sheath, which ensures the rapid transmission of electrical impulses and relevant information to the functional centers.

The white matter of the telencephalon forms the cerebral hemispheres, which are the most developed and massive structure of the CNS. This feature is due to the presence of a large number of projection fields in the cortex, which require a developed network of connecting fibers for their normal functioning. Otherwise, communication and parallel execution of the higher mental functions of the brain are disrupted: for example, speech becomes slow and inarticulate.

In the middle section of the brain, white matter is located mainly over its entire surface, as well as ventrally from the gray matter of the colliculus quadrigemina. It also consists of the upper legs that connect the midbrain with the cerebellum and transmit efferent information from this motor center to other parts of the central nervous system.

The white matter of the oblong section includes all types of fibers: both long and short. The long ones perform a transitory function and connect the descending pyramidal pathways with the spinal nerve cords, and also carry out the coordinated work of the medulla oblongata with thalamic structures, while the short ones form a connection between the nuclei of this department and send information to the overlying structures of the central nervous system.

What is gray matter made up of?

As mentioned earlier, the brain tissue has a complex structure. The main components of the human NS, as well as other mammals, are gray and white matter, while the first component is a dense accumulation of neuron bodies, their dendrites and glial cells, which are the basis or backbone of this substance.

Basically, the gray matter of the brain tissue is formed by accumulations of the bodies of various neurons and their dendrites. The functional feature of this NS unit is that these cells are able to be excited with the help of a special impulse, process, transmit and store the information received in this way.

Like any other living cell in the body, it has its own nucleus, shell and processes, uniting a group of similar structures into a single whole. The study of this unit of NS is complicated not only by its small size, but also by its location, since their largest accumulation is most often located in hard-to-reach places, intervention in which is fraught with disastrous consequences.

The functional significance of glial cells is very diverse: they serve as a barrier to other structures of the body, but in some cases they perform a protective function. A feature of glia is the ability to restore and divide, which other nerve cells cannot boast of. A layer of them forms a special tissue called neuroglia and is located in all parts of the NS.

Since neurons are deprived of protection from the negative effects of the environment and are helpless before mechanical damage, in some cases glia are able to phagocytize or assimilate the incoming foreign antigen, which is dangerous for gray cells.

What is white matter made of?

White matter is a special component of the central nervous system, represented by bundles of nerve fibers covered with a special myelin sheath, due to which the main purpose of this brain structure is fulfilled, which is to transfer information from the main functional centers of the nervous system to the underlying parts of the NS.

The myelin sheath allows you to transmit an electrical impulse over long distances at high speed without loss. It is a derivative of glial cells and, due to its special structure (the membrane is formed from a flat outgrowth of the glial body devoid of cytoplasm), wraps the nerve fiber along the periphery several times, interrupting only in the area of ​​intercepts.

This characteristic feature allows you to increase the strength of the impulse sent by the gray matter several times. In addition, it performs an isolating function that allows you to maintain signal strength throughout the entire axon.

With regard to the chemical composition of white matter, myelin is mainly formed by lipids (organic compounds, including fats and fat-like substances) and proteins, so white matter, at first glance, is a fat-like mass with the corresponding characteristics.

The distribution of white matter in different parts of the CNS is heterogeneous chemical composition: the spinal cord is "fatter" than the head section of the nervous system. This is due to the fact that more efferent information comes out of the gray matter of this department to the peripheral nervous system.

How is gray and white matter distributed in the cerebral hemispheres

For a visual study of the structure of the central nervous system, there are several methods that allow you to see the brain in section. The most informative is the sagittal section, with the help of which the brain tissues are divided into 2 equal parts along the central line. At the same time, to study the location of gray and white matter in the thickness, the frontal section of the anterior section, and, accordingly, the cerebral hemispheres, is ideal, allowing you to highlight the hypothalamus, corpus callosum and fornix.

The white matter of the anterior section is located in the thickness of large lobes, which are the springboard for the gray matter that makes up the cortex. It covers the entire surface of the hemispheres with a kind of cloak and belongs to the structures of the higher nervous activity of a person.

At the same time, the thickness of the gray matter of the cortex is not the same throughout and varies within 1.5-4.5 mm, reaching the greatest development in the central gyrus. Despite this, it occupies about 44% of the volume of the forebrain, as it is located in the form of convolutions and furrows, which make it possible to increase the total area of ​​this structure.

At the base of the white matter of the cerebral hemispheres, there are also separate accumulations of gray matter that make up the basal nuclei. These formations are subcortical structures or central nodes of the base of the final section. Experts identify 4 types of such functional centers, which differ in form and purpose:

1. caudate nucleus;
2. lenticular nucleus;
3. fence;
4. amygdala.

All these structures are separated from each other by layers of white matter, which transmits information from them to the underlying parts of the brain through the black substance located in the middle section, and also connects the nuclei with the cortex and ensures their coordinated work.

What is the danger of damage to white and gray matter

As a result of any pathological processes occurring in the structures of the white and gray matter, the pronounced symptoms of the disease can manifest themselves in different ways and depend on the location of the damaged area and the extent of focal brain damage.

Particularly dangerous diseases are characterized by the presence of several or multiple hard-to-reach lesions, which are aggravated by blurred symptoms, consisting of more signs of pathological changes.

Diseases of the central nervous system, accompanied by changes in the structure of the white matter:

• Leukoatherosis. Refers to many focal changes in the structure of the brain. As a result of this disease, there is a gradual decrease in the density of white matter, located in the hemispheres of the cerebellum and the trunk of this organ. It leads to degenerative changes in human behavior and is not an independent disease, as it most often develops against the background of insufficient supply of nutrients to the nervous tissue.
• The most common cause of a disease such as multiple sclerosis is white matter demyelination or destruction myelin sheath nerve fibres. As with the first disease, the process is multifocal in nature and affects all structures of the central nervous system, which is why it has an extensive clinical picture, which can combine many signs and symptoms of the disease. Typically, patients with multiple sclerosis are easily excitable, have problems with memory and fine motor skills. In especially severe cases, paralysis and other disorders of motor function develop.
• Such pathological condition, as a heterotopia of the gray matter of the brain, is characterized by an atypical location of the neurons of the gray component in the structures of this section of the CNS. It occurs in children with epilepsy and other mental pathologies, such as mental retardation. It is the result of a genetic and chromosomal abnormality in human development.

Advances in modern medicine make it possible to diagnose pathological changes in the medulla is still at the initial stage of development, which is extremely important for subsequent therapeutic actions, since it is known that any progressive changes in the structure of both the white and gray matter of the brain eventually lead to degenerative changes and other severe neurological problems.

Diagnosis of the disease includes a full-time examination of the patient by a neurologist, during which, with the help of special tests, almost all pathological changes in the gray and white matter are detected, without the use of special equipment.

The most informative technique for studying both white and gray matter is MRI and CT, which allow obtaining a number of images of the internal state of brain structures. With the help of these research methods, it became possible to study in detail the general anatomical picture of both single and multiple foci of changes in these functional units of the NS.

Video

If you look at the section of the spinal column, you can see that the white and gray matter of the spinal cord have their own anatomical structure and location, which largely determines the functions and tasks of each of them. The appearance resembles a white butterfly or the letter H, surrounded by three gray cords or bundles of fibers.

Functions of white and gray matter

What is gray matter made up of?

Depending on the anatomical location, it is customary to distinguish between anterior, posterior and lateral sections. Each pillar has its own structure and purpose.

In fact, the gray matter is an accumulation of nerve cells with different purposes and functionality.

What is white matter made of?

Where is the gray matter

In the center of the gray matter is the spinal canal, through which circulation is provided, and, accordingly, the transfer of nutrients to nerve fibers and tissues.

Where is white matter located

The grooves of the spinal tissue delimit the structure of the brain tissue, forming three pillars. The main component of white matter is nerve fibers that quickly and efficiently transmit a signal along the cords to the cerebellum or hemispheres and back.

What is the danger of damage to white and gray matter

Any lesions that affect the anatomical structure are manifested in a violation of the basic functions of the body:

• The defeat of the gray matter - the main task of the segment is to provide reflex and motor function. The defeat manifests itself in numbness, partial or complete paralysis of the limbs.
  Against the background of violations, muscle weakness develops, the inability to perform natural daily tasks. Often, pathological processes are accompanied by problems in defecation and urination.
• Lesions of the white shell - the transmission of nerve impulses to the hemispheres and the cerebellum is disrupted. As a result, the patient experiences dizziness, loss of orientation. There are difficulties in coordinating movement. With severe violations, paralysis of the limbs occurs.

In the brain, gray and white matter are distinguished, but their distribution here is much more complicated than in the spinal cord. Most of the gray matter of the brain is located on the surface of the cerebrum and cerebellum, forming their cortex. A smaller part forms numerous subcortical nuclei surrounded by white matter. All gray matter nuclei are composed of multipolar neurons.

The gray matter contains the bodies of neurons, from which the nuclei of the central nervous system and the cortex are formed. White matter consists of processes of neurons that form bundles and tracts, which are components of the pathways of the central nervous system.

The white matter in the brain occupies the entire space between the gray matter of the cerebral cortex and the basal ganglia. The surface of the hemisphere, the cloak, is formed by a uniform layer of gray matter 1.3–4.5 mm thick, containing nerve cells.

There are four parts in white matter:

the central substance of the corpus callosum, the internal capsule and long associative fibers;

radiant crown (corona radiata), formed by radially diverging fibers entering the inner capsule and leaving it;

the area of ​​white matter in the outer parts of the hemisphere - the semi-oval center;

white matter in the gyri between the sulci.

The nerve fibers of the white matter are divided into projection, associative and commissural.

The white matter of the hemispheres is formed by nerve fibers that connect the cortex of one gyrus with the cortex of other gyri of its own and opposite hemispheres, as well as with underlying formations.

Two cerebral commissures, commissura anterior and commissura fornicis, are much smaller in size, belong to the olfactory brain and connect: commissura anterior - olfactory lobes and both parahippocampal gyrus, commissura fornicis - hippocampi.

The commissural fibers that make up the cerebral commissures, or adhesions, connect not only symmetrical points, but also the cortex belonging to different lobes of opposite hemispheres. Associative fibers connect different parts of the cortex of the same hemisphere. They are divided into short and long fibers.

Short fibers connect adjacent convolutions in the form of arcuate bundles. Long associative fibers connect areas more distant from each other.

The internal capsule is a thick, angled plate of white matter, bounded on the lateral side by the lenticular nucleus, and on the medial side by the head of the caudate nucleus and the thalamus. The internal capsule is formed by projection fibers that connect the cerebral cortex with other parts of the central nervous system. Fibers of the ascending pathways. Diverging in different directions to the cortex of the hemisphere, they form a radiant crown. From top to bottom, the fibers of the descending pathways of the internal capsule in the form of compact bundles are sent to the peduncle of the midbrain. On the frontal section of the brain, the internal capsule looks like an oblique white stripe continuing into the brain stem. In the internal capsule, the anterior leg is distinguished - between the caudate nucleus and the anterior half of the inner surface of the lenticular nucleus, as well as the posterior leg - between the thalamus and the posterior half of the lenticular nucleus and knee. Projection fibers according to their length can be divided into the following three systems:

Fibrae thalamocorticalis et corticothalamici - fibers from the thalamus to the cortex and back from the cortex to the thalamus; conducting excitation towards the cortex and centrifugal (efferent).

Tractus corticonuclearis - pathways to the motor nuclei of the cranial nerves.

Tractus corticospinalis (pyramidalis) - conducts motor volitional impulses to the muscles of the trunk and limbs.

Tractus corticopontini - paths from the cerebral cortex to the nuclei of the bridge. Using these pathways, the cerebral cortex has an inhibitory and regulatory effect on the activity of the cerebellum.

Projection fibers in the white matter of the hemisphere closer to the cortex form a radiant crown, and then their main part converges into the internal capsule.

Medulla.

It contains the nuclei of gray matter, which are related to balance, coordination of movements, as well as to the regulation of metabolism, respiration and blood circulation.

The gray matter of the medulla oblongata is represented by the following nuclei:

1) The nucleus of the olive (nucleus olivaris) has the appearance of a convoluted plate of gray matter, protrudes outward of the medulla oblongata. Lies in the olive. Responsible for balance.

2) The reticular formation (formatio reticularis) is formed from the interweaving of nerve fibers and those lying between the nerve cells. It contains the respiratory and vascular centers. Responsible for ensuring the maintenance of posture and the implementation of locomotion (static vestibular reflexes), the implementation of protective functions (coughing, sneezing, vomiting)

3) The nuclei of the four pairs of lower head nerves (XII - IX).

4) The nuclei of the vagus nerve are the centers of respiration and blood circulation.

5) Wedge-shaped and thin nuclei - switching nuclei.

The white matter of the medulla oblongata contains long and short fibers. The long ones include descending pyramidal tracts passing into the anterior cords of the spinal cord. In the nuclei of the posterior cords are the bodies of the second neurons of the ascending sensory pathways. In the medulla oblongata there are two intersections of long pathways: ventral motor and dorsal sensory.

To shortcuts include bundles of nerve fibers that connect individual nuclei of gray matter, as well as the nuclei of the medulla oblongata with neighboring parts of the brain.

Hind brain.

It consists of two parts: the bridge and the cerebellum. The bridge contains longitudinal and transverse fibers, between which their own nuclei of gray matter are scattered. Longitudinal fibers belong to the pyramidal tracts, which are connected with their own nuclei of the bridge, from which the transverse fibers originate, going to the cerebellar cortex. The surface of the cerebellum is covered with a layer of gray matter that makes up the cerebellar cortex. There are three layers in the cortex:

1 outer, or molecular - contains various cellular elements, but few neurons. It consists mainly of intertwining basilar fibers, i.e. unmyelinated, and contains a small number of irregularly scattered small cell nuclei. It contains parallel fibers and many dendrites of Purkinje cells. Basket neurons and stellate neurons are also located here.

2 ganglionic - contains large pear-shaped cells (Purkinje cells) located in 1 row .. One axon departs from each such cell, extending deep into the cerebellum, and dendrites form a tree above the cell, their branching is perpendicular to the convolutions. These dendrites are equipped with spines.

3 granular, or granular - contains many granular cells. These are the smallest neurons. Their body is mainly occupied by the nucleus, around which there is a narrow layer of protoplasm. There are also two types of Golgi cells: short-axon and long-axon. The former are involved in the formation of the cerebellar lumen, and the latter, entering the white matter of the cerebellum, connect various areas of its cortex. Behind the granular layer is white matter, which contains subcortical nuclei. Allocate:

Globular nucleus (nucleus globosus)

Corky nucleus (n. emboliformis)

Tent core (n.fastigii)

Dentate nucleus (n.dentatus).

There are two types of afferent fibers in the cerebellum: moss and liana. Cerebellar fibers form three pairs of legs:

Lower legs (to medulla oblongata)

Middle legs (to the bridge)

Upper legs (to the roof of the midbrain).

Midbrain.

The midbrain consists of the quadrigemina, which includes 2 pairs of upper and lower hillocks. The midbrain also includes 2 pairs of knobs of the hillocks. The upper colliculi contain the visual nuclei, and the lower colliculi contain the auditory nuclei. It contains red nuclei and black matter, which belong to a fiber system that does not pass through the pyramid of the medulla oblongata. They regulate automatic unconscious movements. The substantia nigra secretes the hormone dopamine, which suppresses the excessive activity of the motor nuclei of the telencephalon. The nuclei of the III and IX cranial nerves are located in the central gray matter.

The white matter of the midbrain is a descending tract connecting the red nuclei and the anterior horns of the spinal cord. The bundles, at the exit from the red nucleus, intersect with each other, forming a ventral decussation of the tegmentum. The tegmentum contains longitudinal ascending fibers that form a continuation of the medial and lateral loops in the midbrain. As part of these loops, sensitive impulses go to the large brain. In the midbrain there is a medial longitudinal bundle, which is associative. It connects the various nuclei of the nerves of the eye muscles with each other. Another of its functions is associated with the movement of the eyes and head during stimulation of the vestibular apparatus.

Intermediate brain.

The diencephalon consists of the thalamus, epithalamus, thalamus, and hypothalamus.

The thalamus is a large paired accumulation of ovoid gray matter. These accumulations are located in the lateral walls of the diencephalon on the sides of the third ventricle. Their medial surface, covered with a thin layer of gray matter, protrudes freely into the cavity of the third ventricle, being its lateral wall; on this surface passes the hypothalamic groove (sulcus hypothalamicus), delimiting the thalamus from the hypothalamus. The dorsal surface is covered with a thin layer of white matter. The gray matter, which is part of the thalamus, forms the nuclei of the thalamus. The main nuclei of the thalamus are: 1. Anterior nucleus (nucleus anterior thalami); 2. Medial nucleus (nucleus medialis thalami); 3. Lateral nucleus (nucleus lateralis).

Part of the processes of thalamic neurons goes to the nuclei of the striatum of the telencephalon (in this regard, the thalamus is considered as a sensitive center of the extrapyramidal system), and part - thalamocortical bundles (fasciculi thalamocorticales) - to the cerebral cortex.

The epithalamus includes the triangle of the leash (trigonum habenulae), the leash (habenula), the commissure (adhesion) of the leashes (commissura habenularum), and the pineal body (corpus pineale).

The leash includes a triangle of the leash and a soldering of the leashes. In the triangle of the leash lies an accumulation of gray matter - the core of the leash, in the cells of which most of the fibers of the brain strip of the thalamus terminate. A smaller part of the fibers passes through the commissure of the leash; at the same time, some of them connect with the cells of the node of the leash of the opposite side, others reach the upper tubercle of the roof of the midbrain, the opposite side;

Anterior and inferior to the pineal body is a bundle of transverse fibers - the epithalamic commissure. It is a curved plate protruding into the cavity of the third ventricle. Between the epithalamic commissure and the commissure of the leashes, a shallow blind pocket protrudes into the anterior upper part of the pineal body, into its base - the pineal depression.

Metathalamus includes geniculate bodies - paired formations in which the ascending fibers of the auditory system switch to the auditory cortex and the ascending optic fibers to the visual cortex. Distinguish between the medial geniculate body and the lateral geniculate body.

The hypothalamus unites formations located ventrally under the bottom of the third ventricle; lies down from the visual hillock, under the hypotuberous furrow (sulcus hypothalamicus). The entire hypothalamus is divided into two sections - anterior and posterior. The anterior section includes a gray tubercle, consisting of a thin plate of gray matter. In the posterior region is the optic chiasm, formed by the chiasm optic nerves, and mastoid bodies. These are two small elevations of irregular spherical shape. Outside, they are covered with white matter, and inside each there are two (medial and lateral) gray nuclei. By function, the mastoid bodies belong to the subcortical olfactory centers.

The gray matter of the hypothalamus forms nuclei, which are divided into five groups: preoptic, anterior, middle, outer and posterior groups.

telencephalon

The telencephalon consists of two hemispheres of the large brain, separated by a longitudinal fissure and interconnected in the depths of this fissure with the help of the corpus callosum, anterior and posterior commissures, and also the commissure of the fornix. The composition of the hemispheres of the telencephalon includes three components: the cloak of the telencephalon (pallium), the striatum (corpus striatum) and the septum (septum). The cloak consists of the neocortex - the new cortex, which has six layers, differing from each other mainly in the shape of the nerve cells included in them.

The derivatives of the striatum are the basal nuclei:

The ancient striatum is a pale ball.

Old striatum - amygdala complex

New striatum - caudate nucleus, fence, shell.

In the hemispheres, the following groups of centers are distinguished:

1. The olfactory brain (rhinencephalon) is the oldest and at the same time the smallest part located ventrally.

2. Basal, or central, nuclei of the hemispheres, "subcortex" - the old part of the telencephalon, hidden in the depths.

3. The gray matter of the cortex is the youngest, and at the same time the largest part, covering the rest with a kind of cloak, hence its name “cloak”, or mantle.

Cortex(cloak), is the most highly differentiated department of the nervous system. The cortex is most developed in the region of the central gyrus. The surface area of ​​the cortex increases due to the many furrows. The surface area of ​​both hemispheres is about 1650 cm 2 .

In the cerebral cortex, 11 cytoarchitectonic regions are distinguished, including 52 fields. These fields differ in the composition of neurons and different fibrous structures. The cerebral cortex consists of a huge number of nerve cells, which, according to morphological features, can be divided into six layers:

I. molecular layer

II. outer granular layer

III. outer pyramidal layer

IV. inner granular layer

V. internal pyramidal

VI. polymorphic layer

The surface of the hemisphere - raincoat (pallium) is formed by gray matter 1.3 - 4.5 mm thick. The cloak is divided into main lobes, which differ both in location and in function:

Frontal lobe, lobus frontalis; this is the part of the hemisphere located rostral to the central (Roland) sulcus. The lower edge of the frontal lobe is limited by the anterior edge of the Sylvian furrow;

Parietal lobe, lobus parientalis; located caudal to the central sulcus. The lower edge of the parietal lobe is limited by the posterior edge of the Sylvian furrow. The boundary between the parietal and occipital lobes is conditionally considered to be a line drawn from the point of intersection of the dorsal edge of the hemisphere by the upper end of the parietal-occipital sulcus to the anterior edge of the cerebellum;

Occipital lobe, lobus occipitalis; located behind the parietal-occipital sulcus and its conditional continuation on the upper lateral surface of the hemisphere. Furrows and convolutions of the outer surface of the occipital lobe are very variable;

Temporal lobe, lobus temporalis; rostro-dorsally limited by the Sylvian groove, and the caudal border is drawn according to the same principles as in the parietal lobe;

Islet lobe, lobus insularis (insula); located under the lid of the islet (operculum). The composition of the cover includes small areas of the temporal, parietal and frontal lobes.

The main surface of the lobes of the cloak are furrows and convolutions. Furrows are deep folds of the cloak containing stratified bodies of neurons - the cortex (the gray matter of the cloak) and the processes of cells (the white matter of the cloak). The sulci of the cloak of the telencephalon are divided into 3 main categories, which reflect their depth, occurrence and stability of outlines.

Permanent furrows (I order). A person has 10 of them. These are the deepest folds on the surface of the brain, which change the least in different people. Furrows of the first order appear in the process of early development and are a species trait.

Irregular furrows of the II order. They have a characteristic place and direction, but can vary individually within very wide limits or even be absent. The depth of these furrows is quite large, but much less than that of the furrows of the first order.

Non-permanent furrows of the III order are called grooves. They rarely reach significant sizes, their outlines are variable, and their topology has ethnic or individual characteristics. As a rule, grooves of the III order are not inherited.

The entire space between the gray matter of the cerebral cortex and the basal ganglia is occupied by white matter. It consists of a large number of nerve fibers running in different directions and forming pathways of the telencephalon. Nerve fibers can be divided into 3 systems: associative, commissural and projection waves.

CONCLUSION

So, we can conclude that in the human body the work of all its organs is closely interconnected, and therefore the body functions as a whole. The coordination of the functions of the internal organs is provided by the nervous system, which, in addition, communicates the body as a whole with the external environment and controls the work of each organ.

The nervous system plays an important role in the regulation of body functions. It ensures the coordinated work of cells, tissues, organs and their systems. In this case, the body functions as a whole. Thanks to the nervous system, the body communicates with the external environment.

The activity of the nervous system is the basis of feelings, learning, memory, speech and thinking - mental processes, with the help of which a person not only learns environment, but can also actively change it.

Distinguish between the central nervous system (brain and spinal cord) and the peripheral, represented by nerves extending from the brain and spinal cord and other elements that lie outside the spinal cord and brain. The entire nervous system is divided into somatic and autonomic.

The brain is made up of gray and white matter. Gray matter is a collection of neurons and their short processes. In the spinal cord, it is located in the center, surrounding the spinal canal. In the brain, on the contrary, the gray matter is located on its surface, forming a cortex and separate clusters, called nuclei, concentrated in the white matter. The white matter is under the gray and is composed of sheathed nerve fibers. Nerve fibers, connecting, compose nerve bundles, and several such bundles form individual nerves. The spinal cord is located in the spinal canal and looks like a white cord stretching from the occipital foramen to the lower back. Longitudinal grooves are located along the anterior and posterior surfaces of the spinal cord, in the center there is a spinal canal, around which gray matter is concentrated - an accumulation of a huge number of nerve cells that form the contour of a butterfly. On the outer surface of the cord of the spinal cord is white matter - an accumulation of bundles of long processes of nerve cells.

LIST OF USED LITERATURE

1. Bets L.V. Lectures on the anatomy of the central nervous system (compendium)

2. Sinelnikov R.D. Atlas of human anatomy, volume 3. Medicine, Moscow 1974.

3. S.V. Saveliev, M.A. Negasheva. Workshop on the anatomy of the human brain. Lead, Moscow, 2001.

4. Baritonov I.S. Structure and functions of the cerebral cortex. Science 1969.

5. Sapin M. R. Human anatomy. Book 2. Higher School 1996.

6. Rassolimo T. E. Anatomy of the CNS Reader.