The section of the brain located at the very front of the skull is called the terminal section. It is in this department that such vital centers as the center of higher nervous activity and the emergence of conditioned reflexes, regulation of movements and speech pronunciation, centers of vision, hearing, smell, taste, as well as skin and muscle sensitivity are located.

The telencephalon is divided into two hemispheres by a longitudinal fissure. hemispheriae cerebrates , connected to each other through a system of adhesions.

Each hemisphere of the telencephalon consists of five lobes:

• Frontal
• Temporal
• Parietal
• Occipital
• Ostrovkovaya.

The hemispheres of the telencephalon have a complex topography due to the presence of grooves and convolutions. The surface of the hemispheres is covered with gray matter - the cerebral cortex.

The elements of the internal structure of the parts of the telencephalon include the basal ganglia, nuclei basales, white matter; the cavity of each hemisphere is the paired lateral ventricle, ventriculus lateralis.

This article describes in detail the anatomical structure and main functions of the telencephalon.

Structure of the human cerebral cortex: cells and zones

The cerebral cortex, cortex cerebri, is the most important part of the central nervous system, being the material substrate of higher nervous activity and the main regulator of all vital functions of the body. The cortex analyzes and synthesizes incoming stimuli from the internal environment of the body and from the surrounding external environment. Consequently, the highest forms of reflection of the external world and conscious human activity are associated with the cerebral cortex.

In phylogenetic terms there are ancient ( paleocortex) , old ( archeocorte x) And new ( neocortex) cerebral cortex. The ancient and old cortex are located on the medial and basal surface of the hemisphere. They are surrounded by intermediate cortical formations that are part of the structure of the cerebral cortex and are called the peripaleocortex and periarchicortex (mesocortex).

Outermost layer- molecular plate, lamina molecularis , contains a small number of small nerve cells and is composed mainly of a dense plexus of nerve fibers lying parallel to the surface of the convolutions.

Second layer- outer granular plate, lamina granulans externa , contains a large number of small, polygonal or round nerve cells.

Third layer- external pyramidal plate, lamina pyramidalis externa , consists of the same small cells as the second layer.

Fourth layer called the internal granular plate lamina granularis interna .

Fifth layer- layer of large pyramidal cells of the cerebral cortex or ganglion, laminaganglionaris , represented by the internal pyramidal plate, lamina pyramidalis interna. Along with fairly large pyramidal cells, it also contains the so-called Betz giant pyramidal cells, which are found only in certain areas of the cortex: in the anterior central gyrus (mainly in its upper section) and in the paracentral I lobule of the medial surface of the hemisphere. Pyramidal cells with their apex face the surface of the brain; the base from which the axon departs is to the white matter. The fifth layer gives rise to the efferent (descending) corticospinal and corticonuclear tracts.

The last layer, lying on the border of the white matter, is polymorphic, lamina multiformis. The structure of this layer of the cerebral cortex, as its name indicates, includes cellular elements of the most diverse shapes (triangular, polygonal, oval, spindle-shaped).

The zone of the three outer layers of the cerebral cortex is usually united under the name of the main outer zone. The three inner layers of the cerebral cortex are the main inner zone.

Activity of the cerebral cortex: main functions

The main functions of the cerebral cortex are determined by the cellular composition and interneuronal connections of the plates. The molecular plate ends with fibers from other layers of the cortex and from the opposite hemisphere. There is an opinion that neurons of the molecular plate are directly related to memory processes. The external granular and external pyramidal plates mainly contain associative neurons that carry out intracortical connections. They enable analytical thought processes. These plates are phylogenetically the youngest; they are highly developed in the cerebral cortex of humans. The internal granular plate is the main afferent layer of the cortex.

On the neurons of this plate, projection nerve fibers coming from the nuclei of the thalamus and geniculate bodies end. The efferent projection fibers of the cortex begin from the pyramidal cells of the internal pyramidal plate. The lamina multiforme contains functionally heterogeneous neurons. Associative and commissural fibers originate from them.

Along with the horizontal organization of the cortex in the form of plates, the principle of vertical modular organization of the cortex is currently being considered. Currently, data have been obtained on the structural and functional relationship of cells in various layers of the cerebral cortex. In this regard, the concept of cortical columns, or modules, was introduced. The modules are based on such structural components as columns of neurons and bundles of their apical dendrites.

Each cortical column is a vertically oriented row of neurons running through all layers of the cortex. It is generally accepted that in the cerebral cortex there are two types of stable genetically determined associations of neurons: micro- and macrocolumns. In the process of life activity, functionally mobile and structurally varying neuron modules can be formed from them.

Microcolumns are considered the main modular subunit in the cortex. It is a vertically oriented strand of cells consisting of approximately 110 neurons and passing through all the plates of the cortex. Cortical columns are modules, information processing units that have their own input and output. The diameter of the columns is about 30 µm. In almost all areas of the cortex, the number of neurons in the columns is relatively constant, and only in the cortical visual centers the number of neurons in the columns is greater. Several hundred microcolumns are combined into a larger structure - a macrocolumn, having a diameter of 500 to 1000 μm. The cortical columns are surrounded by radially arranged nerve fibers and blood vessels.

Each such module is considered as a focus of convergence of several thousand local, associative and callosal fibers. There are topographically ordered neural connections between the cortical columns and subcortical formations; certain groups of neurons in the basal ganglia, thalamus, and geniculate bodies correspond to individual columns.

The simplest and most constant associations of neuron elements are bundles of dendrites. Vertical bundles of dendrites appear to play the main constructive role in the consolidation of neurons. The activity of the cerebral cortex is carried out mainly by the axon terminals of relay efferent fibers, and the macrocolumns - by associative and callosal fibers.

Individual dendrites in a bundle can be directly adjacent to each other over a considerable distance, which creates favorable conditions for the implementation of non-synaptic influences of the exchange of ions and metabolites. In associations of neurons formed with the help of bundles of dendrites, structural prerequisites are created for both divergence and convergence of synaptic impulses.

From the point of view of myeloarchitectonics, radial and tangential nerve fibers are distinguished in the cortex. The first enter the cortex from the white matter, or vice versa, exit the cortex into the white matter. The latter are located parallel to the surface of the cortex and form plexuses called stripes at a certain depth. There are strips of the molecular plate, outer and inner granular plates, and internal pyramidal plate. The functions of the fibers of the cerebral cortex of the cerebral hemispheres, passing in the stripes, are to connect the neurons of neighboring cortical columns with each other. The number of stripes in different fields of the cortex is not the same. Depending on it, single-strip, double-strip and multi-strip types of cortex are distinguished. The stripes are especially well defined in the occipital lobe, in the visual fields (striate cortex).

Based on numerous clinical, pathological, electrophysiological and morphological studies, the functional significance of various areas of the cerebral cortex has been clearly established.

Nerve centers of the cerebral cortex

Areas of the cerebral cortex that have characteristic cytoarchitectonics and nerve connections involved in performing certain functions are nerve centers. Damage to such areas of the cortex manifests itself in the loss of their inherent functions. The nerve centers of the cloak can be divided into projection and associative.

Projection centers of the cerebral cortex are areas that represent the cortical part of the analyzer and have a direct morphofunctional connection through afferent or efferent nerve pathways with neurons of the subcortical centers.

Association centers are areas of the human cerebral cortex that do not have a direct connection with subcortical formations, but are connected by a temporary two-way connection with projection centers. Associative centers play a primary role in the implementation of higher nervous activity. At present, the dynamic localization of some functions of the cerebral cortex has been clarified quite accurately. Areas of the cerebral cortex that are not projection or associative centers are involved in inter-analyzer integrative brain activity.

Cortical fields are functionally unequal and can be divided into primary, secondary and tertiary.

Primary fields are clearly demarcated areas that correspond to the central parts of the analyzers. The bulk of signals from the sensory organs pass into these fields along specific projection afferent pathways. Primary fields are characterized by strong development of the internal granular plate. Primary fields are associated with the relay nuclei of the thalamus and the nuclei of the geniculate bodies. They have a screen structure and, as a rule, a rigid somatotopic projection, in which individual areas of the periphery are projected into the corresponding areas of the cortex. Damage to the primary fields of the cortex is accompanied by a violation of direct perception and fine differentiation of stimuli.

The secondary fields of the cortex are adjacent to the primary fields. They can be considered as peripheral parts of cortical analyzers. These fields are associated with the association nuclei of the thalamus. When secondary fields are damaged, elementary sensations are preserved, but the ability to more complex perceptions is impaired. Secondary fields do not have clear boundaries, and the somatotopic projection is not expressed in them.

The tertiary fields of the cortex are distinguished by the finest neural structure and the predominance of associative elements. These fields are connected to the posterior nuclei of the thalamus. In the tertiary fields, the most complex interactions of analyzers are carried out, underlying the cognitive process (gnosis), and programs of purposeful actions are formed (praxia).

The cortex provides a perfect organization of animal behavior based on innate and acquired functions during ontogenesis and has the following morphofunctional features:

1. Multilayer arrangement of neurons;
2. Modular principle of organization;
3. Somatotopic localization of receptive systems;
4. Screen display, i.e. distribution of external reception on the plane of the neuronal field of the cortical end of the analyzer;
5. Dependence of the level of activity on the influence of subcortical structures and reticular formation;
6. Availability of representation of all functions of the underlying structures of the central nervous system;
7. Cytoarchitectonic distribution into fields;
8. The presence in specific projection sensory and motor systems of secondary and tertiary fields with associative functions;
9. Availability of specialized associative areas;
10. Dynamic localization of functions, expressed in the possibility of compensation for the functions of lost structures;
11. Overlap of zones of neighboring peripheral receptive fields in the cerebral cortex;
12. Possibility of long-term preservation of traces of irritation;
13. Reciprocal functional relationship between excitatory and inhibitory states;
14. The ability to irradiate (spread) excitation and inhibition;
15. The presence of specific electrical activity.

What do the central and peripheral parts of the olfactory brain include?

The olfactory brain is a sensory area of ​​the cerebral cortex and develops from the ventral part of the telencephalon. The olfactory brain consists of two sections: peripheral and central.

The olfactory lobe or peripheral part of the olfactory brain includes formations located at the base of the brain:

1. Olfactory bulb bulbus olfactorius;
2. Olfactory tract, tractus olfactorius;
3. Olfactory triangle trigonum olfactorium;
4. Anterior perforated substance, substantia perforata anterior.

The central part of the olfactory brain includes:

• vaulted gyrus, gyrusfornica tus, which ends near the temporal pole with a hook, uncus’,
• Leg of the sea horse, or Ammon's horn, hippocampus, ( cornu Ammoni) - a specially shaped formation located in the cavity of the lower horn of the lateral ventricle;
• dentate gyrus, gyrus dentatus , found in the form of a narrow strip in the depths of the hippocampal sulcus, under the foot of the seahorse.

The next section of the article describes the limbic system of the brain, its structure and functions.

Anatomical structure of the limbic system of the brain

The limbic system of the brain is a functional association of brain structures involved in the organization of emotional and motivational behavior, such as food, sexual, and defensive instincts. This system is involved in organizing the sleep-wake cycle.

The Latin word limbus means border, edge. The limbic system of the human brain is so named because the cortical structures included in it are located on the edge of the neocortex and, as it were, border the brain stem.

The limbic system of the brain, as a phylogenetically ancient formation, has a regulatory influence on the cerebral cortex and subcortical structures, establishing the necessary correspondence between their activity levels.

Thus, the limbic system is related to regulating the level of reaction of the autonomous, somatic systems during emotional and motivational activity, regulating the level of attention, perception, and reproduction of emotionally significant information. The limbic system determines the choice and implementation of adaptive forms of behavior, the dynamics of innate forms of behavior, the maintenance of homeostasis, and generative processes. Finally, it ensures the creation of an emotional background, the formation and implementation of processes of higher nervous activity.

Currently, the connections between the structures of the limbic system of the brain are well known, organizing circles and having their own functional specificity. These include the Peypes circle (hippocampus - mammillary bodies - anterior nuclei of the thalamus - cingulate cortex - parahippocampal gyrus - hippocampus). This circle is related to memory and learning processes.

Another circle (amygdala - hypothalamus - mesencephalic structures - amygdala) regulates aggressive-defensive, eating and sexual behaviors.

It is believed that figurative (iconic) memory is formed by the cortico-limbic-thalamo-cortical circle. Circles of different functional purposes connect the limbic system with many structures of the central nervous system, which allows the latter to implement functions, the specifics of which are determined by the included additional structure.

For example, the inclusion of the caudate nucleus in one of the circles of the limbic system determines its participation in the organization of inhibitory processes of higher nervous activity. The limbic system directs its descending pathways to the reticular formation of the brain stem and to the hypothalamus. Through the hypothalamic-pituitary axis, the limbic system controls the humoral system. The limbic system is characterized by special sensitivity and a special role in its functioning of hormones synthesized in the hypothalamus and secreted by the pituitary gland - oxytocin and vasopressin.

What functions does the limbic system perform in the human brain?

The most multifunctional formations of the limbic system are the hippocampus and amygdala. The physiology of these structures is the most studied.

Amygdala ( corpus amigdaloideum) - subcortical structure of the limbic system, located deep in the temporal lobe of the brain. The neurons of the amygdala of the limbic system of the brain are diverse in function, shape and neurochemical processes in them. The functions of the amygdala of the limbic system of the brain are associated with the provision of defensive behavior, vegetative, motor, emotional reactions, and the motivation of conditioned reflex behavior.

The amygdala reacts with many of its nuclei to visual, auditory, interoceptive, olfactory, and skin irritations, and all these irritations cause a change in the activity of any of the nuclei, i.e. The nuclei of the amygdala are multisensory.

Hippocampus ( hippocampus) , located deep in the temporal lobes of the brain and is the main structure of the limbic system. It has a peculiar curved shape (the hippocampus is translated as a seahorse) and along almost its entire length forms an invagination into the cavity of the lower horn of the lateral ventricle. The hippocampus is actually a fold (gyrus) of the old cortex. The dentate gyrus is fused with it and wraps over it. Numerous connections of the hippocampus with the structures of both the limbic system and other parts of the brain determine its multifunctionality; there is no doubt about its participation in the orientation reflex, alertness reactions, increased attention, in the dynamics of learning, which is more often observed with a high level of emotional stress - fear, aggression, hunger, thirst.

Hypothalamus ( hypothalamus) As a structure of the diencephalon, part of the limbic system of the human brain, it performs the following functions: organizes emotional, behavioral, homeostatic reactions of the body. The hypothalamus has a large number of nerve connections with the cerebral cortex, subcortical ganglia, thalamus optic, midbrain, pons, medulla oblongata and spinal cord. The organization of afferent and efferent connections of the hypothalamus indicates that it serves as an important integrative center for somatic, autonomic and endocrine functions.

The lateral nuclei of the hypothalamus form bilateral connections with the upper parts of the brainstem, the central gray matter of the midbrain (limbic area of ​​the midbrain), and the limbic system. Sensitive signals from the surface of the body and internal organs enter the hypothalamus along the ascending spinal-bulbo-reticular tract.

The medial nuclei of the hypothalamus have bilateral connections with the lateral ones and, in addition, directly receive a number of signals from other parts of the brain. In the medial region of the hypothalamus there are special neurons that perceive important parameters of blood and cerebrospinal fluid; in other words, these neurons monitor the state of the body's internal environment. They can perceive, for example, blood temperature (“thermal” neurons), the salt composition of the plasma (osmoreceptors) or the content of hormones in the blood. Through neural mechanisms, the medial region of the hypothalamus controls the activity of the neurohypophysis, and through hormonal mechanisms, the adenohypophysis. Thus, this region serves as an intermediate link between the nervous and endocrine systems, representing the “neuroendocrine interface.”

Subcortical basal ganglia of the brain

The basal subcortical nuclei of the brain, nuclei basales, are accumulations of gray matter in the lower parts of the hemispheres. They are phylogenetically old formations. They are isolated as the stem part of the telencephalon. The basal ganglia include the striatum, the cervical corpus, and the amygdala.

Of the subcortical nuclei of the telencephalon, the caudate nucleus and putamen are united under the name striatum, corpus striatum, and together with the globus pallidus, globus pallidus, they form the so-called striopallidal system. This association is due to the functional relationship. These structures mutually balance each other and, thanks to this, have an optimal influence on motor acts.

Being the highest department of the extrapyramidal system, they ensure the performance of various involuntary (automated) movements, regulate the state of muscle tone, and, consequently, influence the nature of voluntary movements. Moreover, in a single functional system, the pallidum has an activating effect on the subcortical formations of the extrapyramidal system, and the striatum has an inhibitory effect. The striopallidal system receives afferent information from neurons in the medial nucleus of the thalamus.

In addition, the striatal system has connections with the cerebral cortex, in particular with the frontal, temporal and occipital lobes. The efferent corticostriatal pathway, tractus corticostriatus, ends in the striatum. In turn, the striatal system sends inhibitory efferent impulses to the neurons of the globus pallidus. From the latter, efferent impulses reach the neurons of the motor nuclei of the spinal cord and cranial nerves. It should be noted that most of the nerve fibers along the path from the subcortical nodes to the cells of the motor nuclei pass to the opposite side. Thus, the subcortical nodes of each cerebral hemisphere are connected mainly with the opposite half of the body.

The striopallidal system receives afferent fibers from the nonspecific medial thalamic nuclei, the frontal parts of the cerebral cortex, the cerebellar cortex and the substantia nigra of the midbrain. The bulk of the efferent fibers of the striatum converge in radial bundles to the globus pallidus. Thus, the globus pallidus is the output structure of the striopallidal system. Efferent fibers of the globus pallidus go to the anterior nuclei of the thalamus, which are connected to the frontal and parietal cortex of the cerebral hemispheres. Some of the efferent fibers that do not switch in the nucleus of the globus pallidus go to the substantia nigra and the red nucleus of the midbrain. The striopallidum, together with its pathways, is part of the extrapyramidal system, which has a tonic effect on motor activity. This motor control system is called extrapyramidal because it switches on its way to the spinal cord, bypassing the pyramids of the medulla oblongata.

The striopallidal system is the highest center of involuntary and automated movements, reduces muscle tone, and inhibits movements carried out by the motor cortex.

The basal nuclei of the brain (right and left hemispheres) are interconnected by commissural fibers that run as part of the posterior commissure of the brain. This ensures their combined work to perform automated, usually stereotypical, but rather complex reflex motor acts, including locomotor ones (walking, swimming, eating, etc.), which a person performs “without thinking.”

The close connection of the striopallidal system with the nuclei of the hypothalamus (posterior group of hypothalamic nuclei) explains the possibility of its influence on emotional reactions.

Caudate nucleus ( nucleus caudatus) and the shell (putamen) are evolutionarily later (neostriatum) formations than the globus pallidus (paleostriatum) and functionally have an inhibitory effect on it. The abundance and nature of the connections between the caudate nucleus and the putamen indicate their participation in integrative processes, the organization and regulation of movements, and the regulation of the work of vegetative organs. In the interactions between the caudate nucleus and the globus pallidus, inhibitory influences prevail. The interaction of the substantia nigra and the caudate nucleus is based on direct and feedback connections between them.

Pale Ball ( globus pallidus, pallidum) has predominantly large type I Golgi neurons. Connections between the globus pallidus and the thalamus, putamen, caudate nucleus, midbrain, hypothalamus, somatosensory system, etc. indicate its participation in the organization of simple and complex forms of behavior.

Fence ( claustrum) contains polymorphic neurons of different types. It forms connections primarily with the cerebral cortex.

The deep localization and small size of the fence present certain difficulties for its physiological study. This subcortical nucleus of the brain has the form of a narrow strip of gray matter located under the cerebral cortex in the depths of the white matter.

It is known that the thickness of the fence of the left hemisphere in humans is somewhat greater than that of the right; When the right hemisphere fence is damaged, speech disorders are observed.

Thus, the basal ganglia of the brain are integrative centers for the organization of motor skills, emotions, and higher nervous activity.

The amygdala is a complex of the basal nuclei of the cerebral hemispheres, located in the anterior pole of the temporal lobe of the hemisphere and directly in contact with the cortex of the parahippocampal gyrus. They are approached by fibers from the olfactory tract, thalamus and cortex. The efferent pathways of the amygdala run in the stria terminalis. The amygdala belongs to the limbic system.

Functions of white matter fibers of the cerebral hemispheres

The fibers of the white matter of the cerebral hemispheres can be divided into three groups: associative, commissural and projection.

Commissural fibers connect the symmetrical parts of the cerebral hemispheres. Unlike associative ones, they have a predominantly transverse course.

Association fibers of the white matter of the brain connect different parts of the cortex within the same hemisphere. Association fibers that do not extend beyond the cortex are called intracortical association fibers. Those associative fibers that, connecting individual areas of the cortex, exit the cortex into the white matter of the cerebral hemispheres in order to return to the cortex in another place, are called extracortical associative fibers. They are divided into two groups - short and long.

Projection fibers connect the cerebral cortex with the underlying sections, penetrating the hemispheres in the vertical direction. Most projection paths pass through the internal capsule.

Long associative paths include:

1. Upper longitudinal fascicle ( fasciculus longitudinalis superior) - is located in the upper part of the white matter of the cerebral hemisphere and connects the cortex of the frontal lobe with the parietal and occipital lobes.
2. Lower longitudinal fascicle ( fasciculus longitudinalis inferior) - is located in the lower parts of the hemisphere and connects the cortex of the temporal lobe with the occipital lobe.
3. Hook-shaped bundle ( fasciculus uncinatus) - arcing in front of the insula, connects the cortex of the frontal pole with the anterior part of the temporal lobe.
4. Belt ( cingulum) - covers the corpus callosum in the form of a ring and connects areas of the cortex in the frontal, occipital and temporal lobes.
5. Subcallosal fascicle ( fasciculus subcallosus) - located outward from the cingulate bundle and connects areas of the cortex in the frontal gyri and in the gyri of the lateral surface of the occipital lobe.

Projection nerve fibers running from the cerebral hemisphere to its underlying parts make up the internal capsule and its corona radiata. Downward, the fibers of the descending pathways of the internal capsule in the form of compact bundles are directed to the peduncle of the midbrain.

First, the fibers of the white matter of the cerebral hemispheres pass through the anterior leg of the internal capsule, which connect the thalamus with the frontal lobe cortex. These are thalamocortical and corticothalamic bundles. In addition, the frontopontine tract passes through the anterior limb of the internal capsule. Corticonuclear fibers pass through the knee of the internal capsule, that is, that part of the motor pyramidal tract that conducts voluntary impulses to contract the muscles of the head and neck.

In the posterior leg of the internal capsule near the knee there are fibers of the corticospinal (pyramidal) tract - that part of the main motor pyramidal tract that conducts voluntary impulses to muscle contractions from the motor center of the cortex to the anterior horns of the gray matter of the spinal cord. Next to the corticospinal tract, in the next segment of the posterior part of the internal capsule there are ascending thalamocortical fibers, which, arising in the thalamus, are sent to the parietal lobe of the hemisphere. Sensitive impulses of the general skin and muscle senses are carried through them. Even further posteriorly, the fibers of the temporo-occipital-pontine tract pass through the posterior limb of the internal capsule.

In that part of the internal capsule, which is located posterior to the lentiform nucleus, fibers of the white matter of the cerebral hemispheres pass, arising in the lateral geniculate body and heading to the visual center of the cortex. Finally, in that part of the internal capsule, which is located below the lenticular nucleus, the fibers of the auditory tract pass. They begin in the medial geniculate body and end in the cortical auditory center.

Thus, the internal capsule is that layer of white matter of the cerebrum, which is really the gateway for all the centripetal and centrifugal projection paths that go to or from the cortex. The outer and outer capsules are of less importance. Mainly associative bundles of fibers pass here.

Corpus callosum ( corpus callosum) contains commissural fibers connecting the cortex of the right and left hemispheres of the brain. The upper surface of the corpus callosum has a gray covering, indusium griseum, and longitudinal stripes, striae longitudinales corporis callosi, which are part of the olfactory brain. In the corpus callosum there are fibers connecting new, younger sections of the cortex (neopaleum), cortical centers of the right and left hemispheres, in which the fibers of the corpus callosum diverge fan-shaped, forming the radiation of the corpus callosum (radiatio corporis callosi).

The functions of the commissural fibers of the white matter of the brain, running in the knee and beak of the corpus callosum, are to connect with each other the areas of the cortex of the frontal lobes of the right and left hemispheres. Curving anteriorly, the bundles of these fibers seem to cover the anterior part of the longitudinal fissure of the cerebrum on both sides and form the frontal (large) forceps (forceps frontalis major). The trunk of the corpus callosum contains nerve fibers connecting the cortex of the central gyri, parietal and temporal lobes of the two hemispheres of the brain. The splenium of the corpus callosum consists of commissural fibers of the white matter of the brain, its functions are the connection of the occipital cortex and the posterior parts of the parietal lobes of the right and left hemispheres. Curving posteriorly, the bundles of these fibers cover the posterior sections of the longitudinal fissure of the cerebrum and form the occipital (small) forceps (forceps occipitalis minor).

Under the corpus callosum there is a fornix, fornix, consisting of two cords: starting from the fimbriae hippocampi and legs, crus fornicis, connected in the middle part by a commissure of the fornix, comissura fornicis, after which the body of the fornix, corpus fornicis, is formed, which diverges anteriorly and downward on two pillars of the vault, columnae fornicis. The columns of the arch end in the mastoid bodies. Thus, the fornix of the brain (efferent projection pathway) connects the cortex of the temporal lobe (hippocampus) with the diencephalon (with the mammillary bodies of the hypothalamus).

The lateral ventricles, left (first) and right (second), communicate with the third ventricle through the interventricular foramen, foramen interventriculare (Monroi). Through this opening from the cavity of the third ventricle, the choroid plexus, plexus choroideus ventriculi lateralis, penetrates into each lateral ventricle, which extends into the central part, the cavity of the posterior and inferior horns. On the side of the ventricles, the choroid plexus is covered with a thin plate of ependyma, which also lines the walls of all cavities. The choroid plexuses of the ventricles of the brain produce cerebrospinal fluid.

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Anatomy of the telencephalon

General morphology of the cerebral hemispheres, their lobes, main sulci and convolutions, phylogeny of the cerebral hemispheres. Superolateral, medial and inferior surfaces of the cerebral hemispheres, their structures

The telencephalon consists of two hemispheres of the cerebrum, separated from each other by a longitudinal fissure. In the depths of the gap is the corpus callosum connecting them. In addition to the corpus callosum, the hemispheres are also connected by the anterior, posterior commissures and the fornix commissure. Each hemisphere has three poles: frontal, occipital and temporal. Three edges (superior, inferior and medial) divide the hemisphere into three surfaces: superolateral, medial and inferior. Each hemisphere is divided into lobes. The central sulcus (Rolandic) separates the frontal lobe from the parietal lobe, the lateral sulcus (Sylvian) separates the temporal from the frontal and parietal, and the parieto-occipital sulcus separates the parietal and occipital lobes. The insular lobe is located deep in the lateral sulcus. Smaller grooves divide the lobes into convolutions.

Superolateral surface of the cerebral hemisphere. The frontal lobe, located in the anterior section of each cerebral hemisphere, is bounded below by the lateral (Sylvian) fissure, and posteriorly by the deep central sulcus (Rolandic), located in the frontal plane. Anterior to the central sulcus, almost parallel to it, is the precentral sulcus. From the precentral sulcus forward, almost parallel to each other, the superior and inferior frontal sulci run forward, dividing the superolateral surface of the frontal lobe into convolutions. Between the central sulcus behind and the precentral sulcus in front is the precentral gyrus. Above the superior frontal sulcus lies the superior frontal gyrus, which occupies the upper part of the frontal lobe.

The middle frontal gyrus runs between the superior and inferior frontal sulci. Down from the inferior frontal sulcus is the inferior frontal gyrus, into which the ascending and anterior branches of the lateral sulcus project from below, dividing the lower part of the frontal lobe into small gyri. The tegmental part (frontal tegmentum), located between the ascending branch and the lower part of the lateral sulcus, covers the insular lobe, which lies deep in the sulcus. The orbital part lies inferior to the anterior ramus, continuing onto the inferior surface of the frontal lobe. At this point, the lateral sulcus widens, passing into the lateral fossa of the cerebrum.

The parietal lobe, located posterior to the central sulcus, is separated from the occipital parieto-occipital sulcus, which is located on the medial surface of the hemisphere, extending deeply into its upper edge. The parieto-occipital groove passes into the superolateral surface, where the border between the parietal and occipital lobes is a conventional line - the continuation of this groove downwards. The inferior border of the parietal lobe is the posterior branch of the lateral sulcus, separating it from the temporal lobe. The postcentral sulcus runs behind the central sulcus, almost parallel to it.

Between the central and postcentral sulci there is a postcentral gyrus, which at the top passes to the medial surface of the cerebral hemisphere, where it connects with the precentral gyrus of the frontal lobe, forming together with it the precentral lobule. On the superior lateral surface of the hemisphere below, the postcentral gyrus also passes through the precentral gyrus, covering the central sulcus from below. The intraparietal sulcus extends posteriorly from the postcentral sulcus, parallel to the superior edge of the hemisphere. Above the intraparietal sulcus there is a group of small convolutions called the superior parietal lobule; Below is the inferior parietal lobule.

The smallest occipital lobe is located behind the parieto-occipital sulcus and its conventional continuation on the superolateral surface of the hemisphere. The occipital lobe is divided into several convolutions by grooves, of which the transverse occipital groove is the most constant.

The temporal lobe, which occupies the inferolateral parts of the hemisphere, is separated from the frontal and parietal lobes by the lateral sulcus. The insular lobe is covered by the edge of the temporal lobe. On the lateral surface of the temporal lobe, almost parallel to the lateral sulcus, lie the superior and inferior temporal gyri. On the upper surface of the superior temporal gyrus, several weakly defined convolutions (Heschl's gyri) are visible. Between the superior and inferior temporal sulcus is the middle temporal gyrus. Below the inferior temporal sulcus is the inferior temporal gyrus.

The insula (insula) is located deep in the lateral sulcus, covered by a tegmentum formed by parts of the frontal, parietal and temporal lobes. The deep circular fissure of the insula separates the insula from the surrounding parts of the brain. The inferoanterior part of the insula is devoid of grooves and has a slight thickening - the threshold of the insula. On the surface of the insula, a long and a short gyrus are distinguished.

Medial surface of the cerebral hemisphere. All of its lobes, except the insular lobe, take part in the formation of the medial surface of the cerebral hemisphere. The groove of the corpus callosum goes around it from above, separating the corpus callosum from the lumbar gyrus, goes down and forward and continues into the groove of the hippocampus.

The cingulate groove runs above the cingulate gyrus, which begins anteriorly and inferiorly to the beak of the corpus callosum. As it rises, the groove turns back and runs parallel to the groove of the corpus callosum. At the level of its ridge, its marginal part extends upward from the cingulate sulcus, and the sulcus itself continues into the subparietal sulcus. The marginal part of the cingulate sulcus limits the pericentral lobule behind, and the precuneus, which belongs to the parietal lobe, in front. Inferiorly and posteriorly through the isthmus, the cingulate gyrus passes into the parahippocampal gyrus, which ends anteriorly with a hook and is bounded superiorly by the hippocampal sulcus. The cingulate gyrus, isthmus and parahippocampal gyrus are combined under the name vaulted gyrus. The dentate gyrus is located deep in the hippocampal sulcus. At the level of the splenium of the corpus callosum, the marginal part of the cingulate groove branches upward from the cingulate sulcus.

The lower surface of the cerebral hemisphere has the most complex relief. In front is the surface of the frontal lobe, behind it is the temporal pole and the lower surface of the temporal and occipital lobes, between which there is no clear boundary. Between the longitudinal fissure of the hemisphere and the olfactory sulcus of the frontal lobe there is a straight gyrus. Lateral to the olfactory sulcus lie the orbital gyri. The lingual gyrus of the occipital lobe is limited on the lateral side by the occipitotemporal (collateral) groove. This groove passes to the inferior surface of the temporal lobe, dividing the parahippocampal and medial occipitotemporal gyri. Anterior to the occipitotemporal sulcus is the nasal sulcus, which borders the anterior end of the parahippocampal gyrus - the uncus. The occipitotemporal sulcus separates the medial and lateral occipitotemporal gyri.

On the medial and lower surfaces there are a number of formations related to the limbic system (from the Latin Limbus-border). These are the olfactory bulb, olfactory tract, olfactory triangle, anterior perforated substance, mammillary bodies located on the lower surface of the frontal lobe (peripheral part of the olfactory brain), as well as the cingulate, parahippocampal (together with the hook) and dentate gyri. The subcortical structures of the limbic system are the amygdala, septal nuclei and anterior thalamic nucleus.

The limbic system is connected to other areas of the brain: with the hypothalamus, and through it with the midbrain, the temporal cortex and the frontal lobe. The latter, apparently, regulates the functions of the limbic system. The limbic system is a morphological substrate that controls a person’s emotional behavior and controls his general adaptation to environmental conditions. All signals coming from the analyzers, on their way to the corresponding centers of the cerebral cortex, pass through one or more structures of the limbic system. Descending signals from the cerebral cortex also pass through the limbic structures.

The structure of the cerebral cortex. The cerebral cortex is formed by gray matter, which lies along the periphery (on the surface) of the cerebral hemispheres. The cerebral cortex is dominated by the neocortex (about 90%) - the new cortex, which first appeared in mammals. Phylogenetically more ancient areas of the cortex include the old cortex - the archecortex (dentate gyrus and base of the hippocampus) as well as the ancient cortex - the paleocortex (preperiform, preamygdala and entorhinal regions). The thickness of the cortex in different parts of the hemispheres ranges from 1.3 to 5 mm. The thickest cortex is located in the upper parts of the precentral and postcentral gyri and at the paracentral lobule. The cortex of the convex surface of the gyri is thicker than that of the lateral and bottom of the grooves. The surface area of ​​the cerebral cortex of an adult reaches 450,000 cm2, one third of which covers the convex parts of the gyri and two thirds cover the lateral and lower walls of the sulci. The cortex contains 10-14 billion neurons, each of which forms synapses with approximately 8-10 thousand others.

For the first time, domestic scientist V.A. Betz showed that the structure and interaction of neurons is not the same in different parts of the cortex, which determines its neurocytoarchenics. Cells of more or less the same structure are arranged in the form of separate layers (plates). In the neocortex, the cell bodies of neurons form six layers. In different sections, the thickness of the layers, the nature of their boundaries, the size of the cells, their number, etc. vary. The cerebral cortex is dominated by pyramidal cells of various sizes (from 10 to 140 µm). Small pyramidal cells located in all layers of the cortex are associative or commissural interneurons. Larger ones generate impulses of voluntary movements, directed to the skeletal muscles through the corresponding motor nuclei of the brain and spinal cord.

On the outside there is a molecular layer. It contains small multipolar associative neurons and many fibers - processes of neurons in the underlying layers, running as part of the tangential layer parallel to the surface of the cortex. The second layer, the outer granular layer, is formed by many small multipolar neurons, the diameter of which does not exceed 10-12 microns. Their dendrites are directed to the molecular layer, where they pass as part of the tangential layer. The third layer of bark is the widest. This is a pyramidal layer that contains pyramidal-shaped neurons, the bodies of which increase in the direction from top to bottom from 10 to 40 µm. This layer is best developed in the precentral gyrus. The axons of large cells of this layer, covered with a myelin sheath, are directed into the white matter, forming association or commissural fibers. The axons of small neurons do not leave the cortex. Large dendrites extending from the top of the pyramidal neurons are directed to the molecular layer, the remaining small dendrites form synapses within the same layer.

The fourth layer, the internal granular layer, is formed by small stellate-shaped neurons. This layer is developed unevenly in different parts of the cortex. The fifth layer, the internal pyramidal layer, which is most well developed in the precentral gyrus, contains pyramidal cells discovered by V.A. Betz in 1874. These are very large nerve cells (up to 80-125 microns), rich in chromatophilic substance. The axons of these cells leave the cortex and form the descending corticospinal and corticonuclear (pyramidal) tracts. Collaterals depart from the axons and go to the cortex, basal ganglia, red nucleus, reticular formation, pontine and olivary nuclei. The sixth layer - polymorphic cells - contains neurons of various shapes and sizes. The axons of these cells are directed into the white matter, and the dendrites are directed into the molecular layer. However, not all of the cortex is built this way. On the medial and lower surfaces of the cerebral hemispheres, sections of the old (archecortex) and ancient (paleocortex) cortex, which has a two- and three-layer structure, have been preserved.

In addition to nerve cells, each cell layer contains nerve fibers. The structure and density of their occurrence are also different in different parts of the crust. Features of the distribution of fibers in the cerebral cortex are defined by the term “myeloarchitecture.” K. Brodman in 1903-1909 identified 52 cytoarchitectonic fields in the cerebral cortex.

O. Vogt and C. Vogt (1919-1920), taking into account the fiber structure, described 150 myeloarchitectonic areas in the cerebral cortex. The Brain Institute of the Academy of Medical Sciences created detailed maps of the cytoarchitectonic fields of the human cerebral cortex (I.N. Filimonov, S.A. Sarkisov). The fibers of the cerebral cortex are divided into commissural, which connect parts of the cortex of both hemispheres, associative, which connect various functional zones of the cortex of the same hemisphere, and projection, which connect the cerebral cortex with the underlying parts of the brain. They form radially oriented layers that end on the cells of the pyramidal layer. In the molecular, internal granular and pyramidal layers there are tangential plates of myelin fibers that form synapses with cortical neurons.

J. Szentagothai (1957) developed the concept of a modular structure of the cerebral cortex. The module is a vertical cylindrical column of the cortex with a diameter of about 300 μm, the center of which is the corticocortical association or commissural fiber extending from the pyramidal cell. They end in all layers of the cortex, and in the first layer they branch into horizontal branches. In the human cerebral cortex there are about 3 million modules.

Thus, the telencephalon consists of two hemispheres: left and right, connected by commissures ( corpus callosum, commissure of the fornix, anterior commissure).

There are three surfaces in each hemisphere: superolateral, medial, lower.

Each hemisphere has 3 edges: top, bottom, middle.

Each hemisphere has: frontal pole, occipital pole, temporal pole.

The surface of the hemispheres is divided by grooves into convolutions. There are gyri of different orders: primary gyri, secondary gyri, tertiary gyri.

Each hemisphere of the telencephalon consists of five shares: frontal, parietal, occipital, temporal, insular.

The frontal lobe is bounded inferiorly by the Sylvian fissure and posteriorly by the Rolandic fissure. Anterior to the central sulcus, almost parallel to it, is the precentral sulcus. From the precentral sulcus, the superior and inferior frontal sulci run forward, dividing the superolateral surface of the frontal lobe into convolutions.

The parietal lobe is separated from the frontal lobe by the central (Rolandic) sulcus, and from the occipital lobe by the parieto-occipital sulcus. The postcentral sulcus runs behind the central sulcus, almost parallel to it. Between the central and postcentral sulci is the postcentral gyrus. The intraparietal sulcus extends posteriorly from the postcentral sulcus.

The occipital lobe is divided into several convolutions by grooves, of which the most constant is the transverse occipital groove.

The temporal lobe is separated from the frontal and parietal lobes by the lateral (Sylvian) fissure. The superior and inferior temporal gyri pass on the lateral surface. On the superior surface of the superior temporal gyrus, several weakly defined transverse gyri of Heschl are visible. Between the superior and inferior is the middle temporal gyrus.

The insula is located deep in the lateral sulcus. The deep circular fissure of the insula separates the insula from the surrounding parts of the brain. The long and short convolutions of the insula are distinguished on the surface.

On the medial surface of the cerebral hemispheres there are:

sulcus of the corpus callosum,

Lumbar gyrus,

hippocampal sulcus,

Vaulted gyrus (cingulate sulcus, parahippocampal gyrus, isthmus),

Dentate gyrus.

The entire surface of the hemispheres is covered with a cloak of gray matter - the cortex. The cerebral cortex consists of six layers:

1. Molecular;

2. External granular;

3. Layer of pyramidal cells;

4. Internal granular;

5. Ganglionic;

6. Layer of polymorphic cells.

The crust is topographically heterogeneous, therefore it is distinguished cytoarchitectonic areas:

1. Frontal,

2. Occipital,

3. Superior parietal,

4. Inferior parietal,

5. Precentral,

6. Postcentral,

7. Temporal

8. Island,

9. Limbic.

All these areas are divided into cytoarchitectological fields, there are more than 50 of them.

The anterior part of the telencephalon is called olfactory brain. They belong to the olfactory brain.

Finite brain (telencephalon) consists of two hemispheres of the cerebrum, separated by a longitudinal fissure and connected to each other in the depths of this fissure by the corpus callosum, anterior and posterior commissures, and the fornix commissure. The cavity of the telencephalon is formed by the right and left lateral ventricles, each of which is located in the corresponding hemisphere. The cerebral hemisphere consists of the outer integument - the cerebral cortex (cloak), the underlying white matter and the accumulations of gray matter located in it - the basal nuclei. The boundary between the telencephalon and the diencephalon following it passes at the place where the internal capsule is adjacent to the lateral side of the thalamus.

Cerebral hemisphere (hemispherium cerehralis) the outside is covered with a thin plate of gray matter - the cerebral cortex. Each hemisphere has three surfaces: the most convex, superolateral; flat, medial, facing the adjacent hemisphere; lower, which has a complex relief corresponding to the internal base of the skull. The relief of the surfaces of the hemispheres is very complex due to the presence of more or less deep grooves of the cerebrum and roller-like elevations located between them - convolutions. The depth, length of furrows and convex convolutions, their shape and direction are very variable.

Superolateral surface of the hemisphere. In the anterior section of each cerebral hemisphere there is a frontal lobe, bounded below by the lateral sulcus (Sylvian fissure), and behind by the deep central sulcus (Fig. 11.25). In front of the central sulcus, almost parallel to it, is the precentral sulcus, from which the superior and inferior frontal sulci run forward, dividing the superolateral surface of the frontal lobe into convolutions. Between the central sulcus posteriorly and the precentral sulcus anteriorly is the precentral gyrus. Above the superior frontal sulcus lies the superior frontal gyrus. The middle frontal gyrus stretches between the superior and inferior frontal sulci

The tegmental part (frontal tegmentum) is located between the ascending branch and the lower part of the precentral sulcus. This part of the frontal lobe received this name because it covers the insula (insula) lying deep in the sulcus.

Posterior to the central sulcus is the parietal lobe. The posterior border of this lobe is the parieto-occipital sulcus. The lower border of the parietal lobe is the lateral sulcus (its posterior branch), which separates this lobe (its anterior sections) from the temporal one. Within the parietal lobe, the postcentral sulcus is distinguished, which lies behind the central sulcus and almost parallel to it. Between the central and postcentral sulci is the postcentral gyrus. At the top, it passes to the medial surface of the cerebral hemisphere, where it connects with the precentral gyrus of the frontal lobe, forming together with it the paracentral lobe. The intraparietal sulcus extends posteriorly from the postcentral sulcus. It is parallel to the upper edge of the hemisphere. Above the intraparietal sulcus there is a group of small convolutions called the superior parietal lobule.

Rice. 11.25. Lateral surface of the hemispheres.

Below this groove lies the inferior parietal lobule, within which two gyri are distinguished: supramarginal and angular. The lower part of the inferior parietal lobule and the adjacent lower parts of the postcentral gyrus, together with the lower part of the precentral gyrus, overhanging the insular lobe, form the frontoparietal operculum of the insula.

The occipital lobe is located behind the parieto-occipital sulcus and its conventional continuation on the superolateral surface of the hemisphere. The occipital lobe ends at the occipital pole. The grooves and convolutions on the superolateral surface of the occipital lobe are highly variable. The transverse occipital groove is most often and better expressed than others.

The temporal lobe occupies the inferolateral parts of the hemisphere and is separated from the frontal and parietal lobes by a deep lateral sulcus. The edge of the temporal lobe, covering the insula, is called the temporal operculum. On the lateral surface of the temporal lobe two grooves are visible - the superior and inferior temporal. The convolutions of the temporal lobe are oriented along the grooves. The superior temporal gyrus is located between the lateral sulcus above and the superior temporal gyrus below. On the upper surface of this gyrus, hidden in the depths of the lateral sulcus, there are two or three short transverse temporal gyri (Heschl’s gyri), separated by transverse temporal sulci. Between the superior and inferior temporal sulci is the middle temporal gyrus. The inferolateral edge of the temporal lobe is occupied by the inferior temporal gyrus, bounded above by the sulcus of the same name. The posterior end of this gyrus continues into the occipital lobe.

The insular lobe (islet, insula) is located deep in the lateral sulcus. The deep circular fissure of the insula separates the insula from the surrounding parts of the brain. On the surface of the insula there are insular convolutions, long and short

Medial surface of the hemisphere. All lobes of the hemisphere, with the exception of the insula, take part in the formation of its medial surface. Above the corpus callosum is the sulcus of the corpus callosum, which continues into the sulcus of the hippocampus.

Above the sulcus of the corpus callosum is the cingulate sulcus. At the level of the splenium of the corpus callosum, it branches upward from the cingulate sulcus edge part. Between the sulcus of the corpus callosum and the cingulate sulcus is the cingulate gyrus. , covering the corpus callosum anteriorly, superiorly and posteriorly. Posterior and inferior to the splenium of the corpus callosum, the cingulate gyrus narrows, forming the isthmus of the cingulate gyrus, which passes downwards into the wider gyrus of the hippocampus. The cingulate gyrus, isthmus and parahippocampal gyrus are known as the vaulted gyrus. In the depths of the hippocampal sulcus there is a rather thin gray stripe, separated by small transverse grooves - the dentate gyrus . The area of ​​the medial surface of the hemisphere, located between the cingulate sulcus and the upper edge of the hemisphere, belongs to the frontal and parietal lobes.

Anterior to the upper edge of the central sulcus is the medial surface of the superior frontal gyrus, and the paracentral lobule is adjacent directly to this area of ​​the central sulcus. Between the marginal part in front and the parietal-occipital sulcus behind there is the precuneus, a part of the hemisphere belonging to the parietal lobe.

On the medial surface of the occipital lobe there are two deep grooves merging with each other at an acute angle, open posteriorly: the parieto-occipital groove, separating the parietal lobe from the occipital lobe, and the calcarine groove. The area of ​​the occipital lobe lying between the parieto-occipital and calcarine grooves is called a wedge. The calcarine groove borders the lingual gyrus above, from which the collateral groove is located below.

The lower surface of the hemisphere. The anterior sections of this surface are formed by the frontal lobe of the hemisphere, behind which the temporal pole protrudes, and there are also the lower surfaces of the temporal and occipital lobes, which pass into one another without noticeable boundaries. On the lower surface of the frontal lobe, somewhat lateral and parallel to the longitudinal fissure of the cerebrum, there is an olfactory groove. Adjacent to it below is the olfactory bulb and the olfactory tract, which passes from behind into the olfactory triangle, in the area of ​​which the medial and lateral olfactory stripes are visible. The area of ​​the frontal lobe between the longitudinal fissure of the cerebrum and the olfactory sulcus is called the direct gyrus. The surface of the frontal lobe lying lateral to the olfactory sulcus , divided by shallow orbital grooves.

In the posterior part of the lower surface of the hemisphere, the collateral groove is clearly visible, lying downward and lateral to the lingual gyrus on the lower surface of the occipital and temporal lobes, lateral to the parahippocampal gyrus. Somewhat anterior to the anterior end of the collateral sulcus is the nasal sulcus. Lateral to the collateral sulcus lies the medial occipitotemporal gyrus. Between this gyrus and the lateral occipitotemporal gyrus located lateral to it is the occipitotemporal sulcus,

A number of parts of the brain, located predominantly on the medial surface of the hemisphere and being the substrate for the formation of such general states as wakefulness, sleep, emotions, behavioral motivation, etc., are identified under the name " limbic system" (Fig. 11.26).

Rice. 11.26. Structures of the limbic system of the brain.

Since these reactions were formed in connection with the primary functions of smell (in phylogenesis), their morphological basis is the parts of the brain that develop from the inferolateral parts of the brain bladder and belong to the so-called olfactory brain ( rhinencephalon). The limbic system consists of the olfactory bulb, olfactory tract, olfactory triangle, anterior perforated substance, located on the lower surface of the frontal lobe (peripheral part of the olfactory brain), as well as the cingulate and parahippocampal (together with the hook) gyrus, dentate gyrus, hippocampus (central part of the olfactory brain ) and some other structures.

Cerebral cortex (cloak) (cortex cerebri, pallium) represented by gray matter located on the periphery of the cerebral hemispheres. The surface area of ​​the cortex of one hemisphere in an adult is on average 220,000 mm 2, with the visible parts of the gyri accounting for 1/3, and the lateral and lower walls of the sulci accounting for 2/3 of the total area of ​​the cortex. The thickness of the bark in different areas is not the same and ranges from 1.5 to 5.0 mm. The greatest thickness is observed in the upper parts of the precentral and postcentral gyri and paracentral lobule.

As V.A. showed Betz, not only the type of nerve cells, but also their relative positions are different in different parts of the cortex. The fiber structure of the cortex (myeloarchitectonics) mainly corresponds to its cellular composition (cytoarchitectonics). Typical for new ( neocortex) The adult cerebral cortex is an arrangement of nerve cells in the form of six layers (lamellae). On the medial and inferior surfaces of the cerebral hemispheres, areas of the old ( archicortex) and ancient ( paleocortex) bark having a two-layer and three-layer structure. 1) molecular plate, external granular plate, 3) external pyramidal plate (layer of small, medium pyramids), internal granular plate, internal pyramidal plate (layer of large pyramids, or Betz cells), multiform (polyform) plate (Fig. 11.27).

Research conducted by scientists from different countries at the end of the 19th and beginning of the 20th centuries made it possible to create cytoarchitectonic maps of the cerebral cortex of humans and animals, which were based on the structural features of the cortex in each part of the hemisphere. K. Brodmann identified 52 cytoarchitectonic fields in the cortex, F. Vogt and O. Vogt, taking into account the fiber structure, described 150 myeloarchitectonic areas in the cerebral cortex.

Plan

Introduction

1.Anatomy of the telencephalon

2. Physiology of the telencephalon

3. Limbic system

4.Associative zones of the cortex

Conclusion

List of used literature

Introduction

The brain is located in the cranial cavity. Its upper surface is convex, and its lower surface - the base of the brain - is thickened and uneven. At the base of the brain, 12 pairs of cranial (or cranial) nerves arise from the brain. The brain is divided into the cerebral hemispheres (the most recent part in evolutionary development) and the brainstem with the cerebellum. The weight of the adult brain is on average 1375 g for men, 1245 g for women. The weight of the brain of a newborn is on average 330 - 340 g. In the embryonic period and in the first years of life, the brain grows intensively, but only by the age of 20 it reaches its final size. Brain and The spinal cord develops on the dorsal (dorsal) side of the embryo from the outer germ layer (ectoderm). At this point, the neural tube is formed with an expansion in the head section of the embryo. Initially, this expansion is represented by three brain vesicles: anterior, middle and posterior (diamond-shaped). Subsequently, the anterior and rhomboid vesicles divide and five brain vesicles are formed: terminal, intermediate, middle, posterior and oblong (accessory). During development, the walls of the brain vesicles grow unevenly: either thickening, or remaining thin in some areas and pushing into the cavity of the vesicle, participating in the formation of the choroid plexuses of the ventricles. The remnants of the cavities of the brain vesicles and the neural tube are the cerebral ventricles and the central canal of the spinal cord. From each brain vesicle certain parts of the brain develop. In this regard, out of the five cerebral vesicles in the brain, five main sections are distinguished: medulla oblongata, hindbrain, midbrain, diencephalon and telencephalon.

1.Anatomy of the telencephalon

The telencephalon develops from the forebrain and consists of highly developed paired parts - the right and left hemispheres and the middle part connecting them. The hemispheres are separated by a longitudinal fissure, in the depth of which lies a plate of white matter, consisting of fibers connecting the two hemispheres - the corpus callosum. Under the corpus callosum there is a vault, which consists of two curved fibrous cords, which are connected to each other in the middle part, and diverge in front and behind, forming the pillars and legs of the vault. Anterior to the columns of the arch is the anterior commissure. Between the anterior part of the corpus callosum and the fornix is ​​a thin vertical plate of brain tissue - a transparent septum.

The hemisphere is formed by gray and white matter. It contains the largest part, covered with grooves and convolutions - a cloak formed by the gray matter lying on the surface - the cortex of the hemispheres; the olfactory brain and accumulations of gray matter inside the hemispheres - the basal ganglia. The last two sections constitute the oldest part of the hemisphere in evolutionary development. The cavities of the telencephalon are the lateral ventricles. In each hemisphere, three surfaces are distinguished: the superolateral (superolateral) is convex according to the cranial vault, the middle (medial) is flat, facing the same surface of the other hemisphere, and the bottom is irregular in shape. The surface of the hemisphere has a complex pattern, thanks to grooves running in different directions and ridges between them - convolutions. The size and shape of the grooves and convolutions are subject to significant individual fluctuations. However, there are several permanent grooves that are clearly expressed in everyone and appear earlier than others during the development of the embryo. They are used to divide the hemispheres into large areas called lobes. Each hemisphere is divided into five lobes: the frontal, parietal, occipital, temporal and hidden lobe, or insula, located deep in the lateral sulcus. The boundary between the frontal and parietal lobes is the central sulcus, and between the parietal and occipital lobes is the parieto-occipital sulcus. The temporal lobe is separated from the rest by the lateral sulcus. On the superolateral surface of the hemisphere in the frontal lobe, there is a precentral sulcus, separating the precentral gyrus, and two frontal sulci: superior and inferior, dividing the rest of the frontal lobe into the superior, middle and inferior frontal gyri. In the parietal lobe there is a postcentral sulcus, separating the postcentral gyrus, and an intraparietal sulcus, dividing the rest of the parietal lobe into the superior and inferior parietal lobes. In the lower lobule, the supramarginal and angular gyri are distinguished. In the temporal lobe, two parallel grooves - the superior and inferior temporal - divide it into the superior, middle and inferior temporal gyri. In the region of the occipital lobe, transverse occipital sulci and gyri are observed. On the medial surface, the sulcus of the corpus callosum and the cingulate are clearly visible, between which the cingulate gyrus is located. Above it, surrounding the central sulcus, lies the paracentral lobule. Between the parietal and occipital lobes runs the parieto-occipital sulcus, and behind it is the calcarine sulcus. The area between them is called a wedge, and the one lying in front is called a pre-wedge. At the point of transition to the lower (basal) surface of the hemisphere lies the medial occipitotemporal, or lingual, gyrus.

On the lower surface, separating the hemisphere from the brain stem, there is a deep groove of the hippocampus (seahorse groove), lateral to which is the parahippocampal gyrus. Laterally, it is separated by a collateral groove from the lateral occipitotemporal gyrus. The insula, located deep in the lateral (side) sulcus, is also covered with grooves and convolutions.

The cerebral cortex is a layer of gray matter up to 4 mm thick. It is formed by layers of nerve cells and fibers arranged in a certain order. The most typically structured areas of the phylogenetically newer cortex consist of six layers of cells; the old and ancient cortex has fewer layers and is simpler in structure. Different areas of the cortex have different cellular and fibrous structures. In this regard, there is a doctrine about the cellular structure of the cortex (cytoarchitectonics) and the fibrous structure (myeloarchitectonics) of the cerebral hemisphere cortex.

The olfactory brain in humans is represented by rudimentary formations, well expressed in animals, and constitutes the oldest parts of the cerebral cortex.

The basal ganglia are clusters of gray matter within the hemispheres. These include the striatum, consisting of the caudate and lenticular nuclei, interconnected. The lenticular nucleus is divided into two parts: the shell, located on the outside, and the globus pallidus, which lies on the inside. They are subcortical motor centers.

Outside the lenticular nucleus there is a thin plate of gray matter - the fence; in the anterior part of the temporal lobe lies the amygdala. Between the basal ganglia and the optic thalamus there are layers of white matter, the inner, outer and outermost capsules. Conducting pathways pass through the internal capsule.

The lateral ventricles (right and left) are cavities of the telencephalon, lie below the level of the corpus callosum in both hemispheres and communicate through the interventricular foramina with the third ventricle. They have an irregular shape and consist of anterior, posterior and lower horns and a central part connecting them. The anterior horn lies in the frontal lobe; it continues posteriorly into the central part, which corresponds to the parietal lobe. At the back, the central part passes into the posterior and inferior horns, located in the occipital and temporal lobes. In the lower horn there is a cushion - the hippocampus (seahorse). From the medial side, the choroid plexus invaginates into the central part of the lateral ventricles, continuing into the inferior horn. The walls of the lateral ventricles are formed by the white matter of the hemispheres and the caudate nuclei. The thalamus is adjacent to the central part below.

The white matter of the hemispheres occupies the space between the cortex and the basal ganglia. It consists of a large number of nerve fibers running in different directions. There are three systems of fibers of the hemispheres: associative (combinative), connecting parts of the same hemisphere; commissural (commissural) connecting parts of the right and left hemispheres, which in the hemispheres include the corpus callosum, anterior commissure and commissure of the fornix, and projection fibers, or pathways connecting the hemispheres with the underlying parts of the brain and spinal cord.

2. Physiology of the telencephalon

The telencephalon, or the cerebral hemispheres, which have reached their highest development in humans, is rightly considered the most complex and most amazing creation of nature.

The functions of this section of the central nervous system are so different from the functions of the trunk and spinal cord that they are allocated to a special chapter of physiology, called higher nervous activity. This term was introduced by I.P. Pavlov. The activity of the nervous system, aimed at uniting and regulating all organs and systems of the body, was called lower nervous activity by I. P. Pavlov. By higher nervous activity he understood behavior, activity aimed at adapting the body to changing environmental conditions, at balancing with the environment. In the behavior of an animal, in its relationships with the environment, the leading role is played by the telencephalon, the organ of consciousness, memory, and in humans - the organ of mental activity and thinking.

The great achievements of I.P. Pavlov in the field of studying the functions of the cerebral hemispheres are explained by the fact that he proved the reflex nature of the activity of the cortex and discovered a new, qualitatively higher type of reflexes inherent only to it, namely conditioned reflexes. Having discovered the basic mechanism of activity of the cerebral cortex, he thereby created a fruitful, progressive method for studying its functions - the method of conditioned reflexes. As it turned out later, conditioned reflexes are those elementary acts, those “bricks” from which a person’s mental activity, or behavior, is built.

Topic 14. Telencephalon.

Telencephalon represented by two hemispheres (hemispheri cerebri). Each hemisphere consists of cloak, or mantle (pallium), olfactory brain (rhinencephalon) And base nodes(basal ganglia). The remnant of the original cavities of both telencephalon vesicles are lateral ventricles (ventriculi lateralis). The forebrain, from which the telencephalon is released, first appears in connection with the olfactory receptor (olfactory brain), and then becomes an organ for controlling the behavior of the animal, and in it centers of instinctive behavior based on species reactions (unconditioned reflexes) arise - subcortical nodes, and centers of individual behavior based on individual experience (conditioned reflexes) - the cerebral cortex. Accordingly, in the telencephalon the following groups of centers are distinguished in order of historical development:

Olfactory brain- the oldest and at the same time the smallest part, located ventrally.

Basal or central nuclei of the hemispheres, "subcortex", the old part of the telencephalon (paleencephalon), hidden in the depths.

New cortex (cortex)- the youngest part (neoencephalon) and at the same time the largest part, covering the rest like a cloak, hence its name - cloak, or mantle.

Since in the process of evolution, the telencephalon grows the fastest and the most among all parts of the central nervous system, in humans it becomes the largest part of the brain and takes on the appearance of two volumetric hemispheres - the right and left .

In the depths of the longitudinal fissure of the brain, both hemispheres are connected by a thick horizontal plate - corpus callosum (corpus collosum), which consists of nerve fibers running transversely from one hemisphere to the other. In the corpus callosum there is a downwardly curved end, or knee ), middle part , and the rear end, thickened in the shape of a roller . All these parts are clearly visible in a longitudinal section of the brain between the hemispheres. The genu of the corpus callosum, bending downwards, becomes pointed and forms a beak , which passes into a thin plate, which in turn continues into the terminal plate.

Rice. 1. Sagittal section of the brain:

1 - frontal lobe; 2 - cingulate gyrus; 3 - corpus callosum; 4 - transparent partition; 5 - vault; 6 - anterior commissure; 7 - visual chiasm; 8 - hypothalamus; 9 - pituitary gland; 10 - temporal lobe; 11 - bridge; 12 - cerebellum; 13 - fourth ventricle; 14 - medulla oblongata; 15 - cerebral aqueduct; 16 - occipital lobe; 17 – roof of the brain; 18 - pineal gland; 19 - parietal lobe; 20 - thalamus.

Under the corpus callosum is the so-called vault (fornix), representing two arched white cords, which in their middle part are connected to each other, and diverge in front and behind, forming arch columns in front , behind are the legs of the arch. The crura of the fornix, heading backward, descend into the inferior horns of the lateral ventricles and pass into the fimbria of the hippocampus . Between the crura of the fornix, under the posterior end of the knee of the corpus callosum, transverse bundles of nerve fibers stretch, forming the commissure of the fornix. The anterior ends of the fornix continue in them to the base of the brain, where they end in the papillary bodies, passing through the gray matter of the hypothalamus. The columns of the fornix limit the interventricular foramina lying behind them, connecting the third ventricle with the lateral ventricles. In front of the columns of the arch is anterior commissure, having the appearance of a white transverse crossbar consisting of nerve fibers. A thin vertical plate of brain tissue is stretched between the front part of the arch and the knee - a transparent septum.

Cerebral cortex. The cerebral cortex is a layer of gray matter, the thickness of which varies in different parts and averages 2-3 mm. The surface of the cortex has a complex topography, characterized by numerous grooves and elevations located between them - convolutions. The gyri differ from each other in shape and size, but the gyri of the same name on the cerebral cortex of different people are fundamentally similar and are localized in certain places. The area of ​​the adult human cortex is about 220,000 mm2, with 2/3 lying deep between the gyri and only 1/3 lying on the surface.

In each hemisphere of the cerebrum there are:

Medial,

Dorsolateral,

Bottom surface.

Dorsolateral surface hemisphere is convex, most extensive, facing upward and laterally, bordering the medial surface with a clearly defined edge.

Flat medial surface facing the midline, in the middle part it is connected by the corpus callosum with the same surface of the other hemisphere.

Bottom surface in the anterior section it is flattened, and in the posterior section it is concave.

Three major sulci divide each hemisphere into four lobes: frontal, parietal, temporal, occipital and insula.

Let us consider the relief of the cerebral cortex.

Rice. 2. Superolateral surface of the hemisphere: 1 – lateral groove; 2 – middle frontal gyrus; 3 – superior frontal gyrus; 4 – precentral gyrus; 5 – superior and inferior precentral sulci; 6 – central groove; 7 – postcentral gyrus; 8 – postcentral sulcus; 9 – intraparietal sulcus; 10 – superior parietal lobe; 11 – inferior parietal lobule; 12 – supramarginal gyrus; 13 – angular gyrus; 14 – occipital pole; 15 – inferior temporal sulcus; 16 – inferior temporal gyrus; 17 – middle temporal gyrus; 18 – superior temporal gyrus; 19 – superior temporal sulcus; 20 inferior frontal sulcus; 21 inferior frontal gyrus; 22 – superior frontal sulcus; 23 – cerebellum; 24 – medulla oblongata.

In the anterior part of each cerebral hemisphere there is frontal lobe.

It ends anteriorly with the frontal pole and is limited inferiorly lateral groove(Sylvian fissure), and behind - deep central sulcus. Lateral sulcus, starting on the lower surface of the hemisphere, goes up the lateral side and then back, dividing the frontal and temporal lobes. Central sulcus located in the frontal plane. It begins in the upper part of the medial surface of the cerebral hemisphere, dissects its upper edge, descends without interruption down the superolateral surface of the hemisphere and ends slightly short of the lateral sulcus. It separates the frontal lobe from the parietal and temporal lobes. Anterior to the central sulcus, almost parallel to it, is located precentral sulcus. The latter ends at the bottom, not reaching the lateral groove. The precentral sulcus is often interrupted in the middle part and consists of two independent sulci. From the precentral sulcus forward are directed superior and inferior frontal sulcus. They are located almost parallel to each other and divide the superolateral surface of the frontal lobe into convolutions. Between the central sulcus posteriorly and the precentral sulcus anteriorly there is precentral gyrus. Above the superior frontal sulcus lies superior frontal gyrus. It stretches between the superior and inferior frontal sulci middle frontal gyrus. Located inferior to the inferior frontal sulcus inferior frontal gyrus. The branches of the lateral sulcus extend into this gyrus from below: ascending branch And anterior branch, which divide the lower part of the frontal lobe into three parts: tire part(frontal operculum), covering the insular lobe (insula) lying deep in the sulcus; triangular part And orbital part.

Posterior to the central sulcus is parietal lobe. The posterior border of this lobe is parieto-occipital sulcus. This groove is located on the medial surface of the hemisphere, deeply dissects the upper edge of the cerebral hemisphere and passes to its superolateral surface. The border between the parietal and occipital lobes on the dorsolateral surface of the cerebral hemisphere is a conventional line - a downward continuation of the parieto-occipital sulcus. The inferior border of the parietal lobe is the lateral sulcus, which separates this lobe from the temporal lobe.

Within parietal lobe allocate nocentral sulcus. It starts from the lateral sulcus below and ends above, not reaching the upper edge of the hemisphere. The postcentral sulcus lies behind the central sulcus and is almost parallel to it. Between the central and postcentral sulci is located postcentral gyrus. At the top, it passes to the medial surface of the cerebral hemisphere, where it connects with the precentral gyrus of the frontal lobe, forming together with it paracentral lobule. It extends posteriorly from the postcentral sulcus intraparietal sulcus. It is parallel to the upper edge of the hemisphere. Above the intraparietal sulcus there is a group of small convolutions called superior parietal lobule. Below this furrow lies inferior parietal lobule, within which two convolutions are distinguished: supramarginal, And corner. The supramarginal gyrus covers the end of the lateral sulcus, and the angular gyrus covers the end of the superior temporal sulcus. The lower part of the inferior parietal lobule and the adjacent lower parts of the postcentral gyrus, together with the lower part of the precentral gyrus, hanging over the insular lobe, form frontoparietal operculum of the insula.

Occipital lobe, is located behind the parieto-occipital sulcus and its conditional continuation on the superolateral surface of the hemisphere. Compared to other lobes, it is small in size. The occipital lobe ends at the occipital pole. The grooves and convolutions on the superolateral surface of the occipital lobe are highly variable. Most often and better expressed than others transverse occipital sulcus, which is like a posterior continuation of the intraparietal sulcus of the parietal lobe.

Temporal lobe, occupies the inferolateral parts of the hemisphere and is separated from the frontal and parietal lobes by the lateral sulcus. The edge of the temporal lobe, covering the insula, is called temporal operculum. The anterior part of the temporal lobe forms the temporal pole. Two grooves are visible on the lateral surface of the temporal lobe - superior and inferior temporal, almost parallel to the lateral groove. The convolutions of the temporal lobe are oriented along the grooves. Superior temporal gyrus, located between the lateral sulcus above and the superior temporal sulcus below. Between the superior and inferior temporal sulcus is middle temporal gyrus. The inferolateral edge of the temporal lobe occupies inferior temporal gyrus, bounded above by the groove of the same name. The posterior end of this gyrus continues into the occipital lobe.

Insula(islet), located deep in the lateral sulcus. This lobe can be seen if the covering of the insula of the frontal, parietal and temporal lobes is expanded or removed. Deep circular groove of the insula separates the insula from the surrounding parts of the brain.

On the medial surface above the corpus callosum, separating it from the rest of the hemisphere, there is sulcus of the corpus callosum. Bending around the back of the corpus callosum, this groove is directed downward and forward and continues into the hippocampal sulcus. Above the sulcus of the corpus callosum is cingulate groove. This groove begins anteriorly and inferiorly from the beak of the corpus callosum, rises upward, then turns back and follows parallel to the groove of the corpus callosum, ends above and posteriorly from the splenium of the corpus callosum as subparietal sulcus. Between the sulcus of the corpus callosum and the cingulate sulcus is cingulate gyrus, covering the corpus callosum anteriorly, superiorly and posteriorly. Posterior and inferior to the splenium of the corpus callosum, the cingulate gyrus narrows, forming isthmus of the cingulate gyrus. Further down and anteriorly the isthmus becomes wider parahippocampal gyrus, bounded superiorly by the hippocampal sulcus. The cingulate gyrus, isthmus and parahippocampal gyrus are known as vaulted gyrus. The dentate gyrus is located deep in the hippocampal sulcus.

On the medial surface of the occipital lobe there are two deep grooves merging with each other at an acute angle, open posteriorly: parieto-occipital sulcus, separating the parietal lobe from the occipital lobe, and calcarine groove. The latter begins on the medial surface of the occipital pole and goes forward to the isthmus of the cingulate gyrus. The area of ​​the occipital lobe lying between the parieto-occipital and calcarine grooves and having the shape of a triangle with its apex facing the junction of these grooves is called wedge. The calcarine groove, clearly visible on the medial surface of the hemisphere, limits the lingual gyrus, extending from the occipital pole posteriorly to the lower part of the isthmus of the cingulate gyrus. Inferior to the lingual gyrus is located collateral groove, already belonging to the lower surface of the hemisphere.

Rice. 3. Medial surface of the hemisphere: 1 – vault; 2 - beak of the corpus callosum; 3 - genu corpus callosum; 4 - trunk of the corpus callosum; 5 - groove of the corpus callosum; 6 - cingulate gyrus; 7 - superior frontal gyrus; 8 -, 10 - cingulate groove; 9 - paracentral lobule; 11 – precuneus; 12 - parieto-occipital groove; 13 – wedge; 14 - calcarine groove; 15 - medial occipitotemporal gyrus; 16 - middle occipitotemporal gyrus; 17 - occipitotemporal groove; 18 - lateral occipitotemporal gyrus; 19 - hippocampal sulcus; 20 - parahippocampal gyrus

The relief of the lower surface of the hemisphere is very complex. The anterior sections of this surface are formed by the frontal lobe of the hemisphere, behind which the temporal pole protrudes, and there are also the lower surfaces of the temporal and occipital lobes, which pass into one another without noticeable boundaries. On the lower surface of the frontal lobe, somewhat lateral and parallel to the longitudinal fissure of the cerebrum, there is olfactory sulcus. Adjacent to it below olfactory bulb And olfactory tract, passing from behind to olfactory triangle. The area of ​​the frontal lobe between the longitudinal fissure of the cerebrum and the olfactory sulcus is called straight gyrus. The surface of the frontal lobe, lying lateral to the olfactory sulcus, is divided by shallow orbital grooves, several variable in shape, location and size orbital gyri.

Rice. 4. Lower surface of the hemisphere: 1- straight gyrus; 2 – olfactory groove; 3 – orbital grooves; 4 – orbital gyri; 5 - anterior perforated substance; 6 – temporo-occipital groove; 7 lateral temporo-occipital gyrus; 8 – medial temporo-occipital gyrus; 9 – collateral groove; 10 - hippocampal sulcus; 11 - medial occipitotemporal gyrus; 12 - calcarine groove; 13 - parahippocampal gyrus; 14 – hook; 15 – mastoid bodies; 16 – midbrain; 17 – olfactory bulb; 18 – olfactory tract; 19 – visual chiasm

In the posterior part of the lower surface of the hemisphere, it is clearly visible collateral groove, lying inferiorly and lateral to the lingual gyrus on the lower surface of the occipital and temporal lobes, lateral to the parahippocampal gyrus, somewhat anterior to the anterior end of the collateral sulcus is located nasal groove, sulcus rhindlis. It borders on the lateral side the curved end of the parahippocampal gyrus - hook. Lateral to the collateral groove lies medial occipitotemporal gyrus. Between this gyrus and the one located outside it lateral occipitotemporal gyrus, located occipitotemporal sulcus.

Olfactory brain. The olfactory brain (rhinencephalon) is phylogenetically the most ancient part of the forebrain, which arose in connection with the olfactory receptor, when the forebrain had not yet become an organ of animal behavior. Therefore, all its components are different parts of the olfactory analyzer. The olfactory brain is located on the lower and medial surfaces of the cerebral hemispheres and is conventionally divided into peripheral and central sections.

TO peripheral department olfactory brain include olfactory bulb And olfactory tract, located on the lower surface of the frontal lobe in the olfactory sulcus. Olfactory tract ends olfactory triangle, which in front of the anterior perforated substance diverges in two olfactory stripes. Lateral stripe ends in the uncinate cortex of the temporal lobe. Medial strip is directed to the subcallosal gyrus and the perioolfactory field, which are located under the beak of the corpus callosum.

TO central department olfactory brain include: vaulted gyrus, hippocampus, dentate gyrus And hook.

Hippocampus- paired formation, represents an invagination of the gray matter from the side of the medial wall of the lower horn of the lateral ventricle. The hippocampus is clearly visible in the cavity of the inferior horn in the form of a club-shaped body. Many afferent systems are diffusely projected into the hippocampus, while efferent influences are directed primarily to the hypothalamus. It is believed that the hippocampus plays a significant role in maintaining the constancy of the internal environment of the body, is involved in the higher coordination of the functions of reproduction and emotional behavior, as well as in the processes of learning and memory retention. The hippocampus is also the center of smell.

Basal ganglia located deep in the white matter of the hemispheres. These include striatum, consisting caudate and lenticular nuclei, amygdala And fence. These nuclei are separated from each other by layers of white matter, forming the inner, outer and outer capsules.

Rice. 5. Basal (subcortical) nuclei on the frontal section of the brain: 1-choroid plexus of the lateral ventricle (central part); 2-thalamus; 3-inner capsule; 4-islet cortex; 5-fence; 6-amygdala; 7-optic tract; 8-mastoid body; 9-pale ball; 10-shell; 11-cerebral vault; 12-caudate nucleus; 13-corpus callosum.

Striatum is divided by a bundle of nerve fibers coming from the cortex and called the internal capsule, into two parts - the caudate nucleus and the putamen. Caudate nucleus It is club-shaped and curved backwards. Its anterior part is expanded, called the head and is located above the lenticular nucleus, and its posterior part, the tail, passes above and lateral to the thalamus, separated from it by the medullary stripes. The head of the caudate nucleus participates in the formation of the lateral wall of the anterior horn of the lateral ventricle. The caudate nucleus consists of small and large pyramidal cells.

Lenticular nucleus located lateral and anterior to the thalamus and caudate nucleus. On the frontal section it has the shape of a triangle. Two parallel vertical layers of white matter divide the lenticular nucleus into 3 parts: shell(most lateral part) and medial and lateral plates globus pallidus. The caudate nucleus and shell are phylogenetically new formations; they are united under the general name neostriatum. The globus pallidus is a more ancient formation, called paleostriatum or pallidum. Together they form the so-called striopallidal system.

The striatum receives afferent impulses mainly from the thalamus, partly from the cortex; sends efferent impulses to the globus pallidus. The striatum is considered as an effector nucleus that does not have independent motor functions, but controls the functions of a phylogenetically older motor center - the globus pallidus. The striatum regulates and partially inhibits the unconditioned reflex activity of the globus pallidus, i.e., it acts on it in the same way as the globus pallidus acts on the red nucleus. The striatum is considered the highest subcortical regulatory and coordination center of the motor system. In the striatum, according to experimental data, there are also higher vegetative coordination centers that regulate metabolism, heat production and heat removal, as well as vascular reactions. Apparently, in the striatum there are centers that integrate and unite unconditioned reflex motor and autonomic reactions into a single holistic act of behavior.

With lesions of the striatum, a person experiences athetosis - stereotypical movements of the limbs, as well as chorea - strong abnormal movements that occur without any order or sequence and involve almost all the muscles (“St. Vitus’s dance”). Both athetosis and chorea are considered as a result of the loss of the inhibitory influence that the striatum has on the pallid nucleus.

Pale ball- a paired formation that is part of the lenticular nucleus and is the motor nucleus. When it is irritated, you can get a contraction of the neck muscles, limbs and the entire torso, mainly on the opposite side. The pallid nucleus receives impulses via afferent fibers coming from the thalamus and closing the thalamopallidal reflex arc. The pallid nucleus, being effector-connected with the centers of the midbrain and hindbrain, regulates and coordinates their work. One of the functions of the pale nucleus is considered to be inhibition of the underlying nuclei, mainly the red nucleus of the midbrain, and therefore, when the globus pallidus is damaged, a strong increase in the tone of the skeletal muscles is observed - hypertonicity, since the red nucleus is freed from the inhibitory influence of the globus pallidus. The thalamo-hypothalamo-pallidal system takes part in higher animals and humans in the implementation of complex unconditioned reflexes - defensive, orientation, food, sexual.

Amygdala nucleus represents a group of nuclei and is localized inside the anterior pole of the temporal lobe, lateral to the septum of the perforated substance. Functionally, it is part of the limbic system and is involved in the regulation of autonomic and neuroendocrine reactions. The amygdala is characterized by a very low threshold of excitation, which may contribute to the development of epileptiform activity. When the amygdala is stimulated, convulsions, emotionally charged reactions, fear, aggression, etc. occur.

Fence - a thin layer of gray matter separated by the outer capsule of white matter from the lenticular nucleus. The fence below is in contact with the cores of the anterior perforated substance. They assume participation in the implementation of oculomotor reactions of tracking an object.

Between the caudate nucleus and the thalamus on one side and the lentiform nucleus on the other there is a layer of white matter called internal capsule. All projection fibers pass through it to the cerebral cortex and from the cortex to the underlying parts of the central nervous system. It is divided into 3 sections: the anterior leg, the knee and the posterior leg.

IN anterior limb of the internal capsule fibers formed by neurons of the frontal areas of the cortex pass through: frontothalamic (tr. frontothalamicus), frontal-red nuclear (tr. frontorubralis) and frontal-pontine (tr. frontopontinus) pathways.

IN knee internal capsule the corticonuclear pathway is located (tr. corticonuclearis).

Hind leg in the anteroposterior direction they form: corticospinal (tr. corticospinalis), thalamo-cortical (tr. thalamocorticalis), occipitotemporopontine (tr. occipitotemporopontinus), auditory radiation (radiatio acustica), visual radiation (radiatio optica). Downward fibers are directed to the peduncles of the midbrain. Above the inner capsule, the fibers form radiant crown.

Internal structure of the new cortex. The human cortex has six layers:

1 - molecular plate,

2 - outer granular plate,

3 - outer pyramidal plate,

4 - internal granular plate.

5 - internal pyramidal plate,

6 - multiform plate.

Rice. 6. Structure of the new cortex. I - molecular plate, II - external granular plate, III - external pyramidal plate, IV - internal granular plate, V - internal pyramidal plate, VI - multiform plate.

molecular plate, is the outermost layer of the cortex, poor in cellular elements. Here there is a dense network formed by the dendrites of pyramidal neurons and axons of cells of other layers. The main purpose of this layer is to ensure interneuronal connections between cells of different layers.

Outer granular plate consists of stellate neurons and small pyramids. In this layer, dichotomous branching of the dendrites of pyramidal neurons occurs, and many horizontal fibers pass through. The main function is the formation of vertical connections.

Outer pyramidal layer contains pyramidal cells of different sizes. Their axons do not form long pathways. Associative afferents end on the neurons of this layer.

Internal granular plate consists of densely arranged stellate neurons. This is where the thalamocortical fibers end.

Inner pyramidal plate contains large and giant pyramids. Their apical dendrites rise into the first layer. The corticonuclear and corticospinal tracts begin from this layer.

Multiform plate contains neurons of transitional forms of different sizes and continues into the white matter without a sharp boundary. Provides upward and horizontal communications.

The functional unit of the cortex is a vertical column consisting of 3-7 cells, they together react to the same stimulus.

Localization of functions in the neocortex. The appearance and relative arrangement of neurons are not the same in different areas of the cortex. Cytoarchitectonic studies (studies of the location of neurons) made it possible to map the cortex. The generally accepted classification of fields by K. Brodmann (1909), which provides for the division of the cortex into 52 fields and the numerical designation of the latter. This numbering formed the basis of the cytoarchitectonic map compiled by the Brain Institute of the Russian Academy of Sciences. In it, a number of fields are divided into zones, designated by Latin letters.

Rice. 7. Cytoarchitectonic map of the cerebral cortex.

The functional significance of various areas of the cortex has now been established. Areas of the cortex with certain cytoarchitecture and characteristic nerve connections involved in performing certain functions are called nerve centers. Traditionally, the centers of the neocortex are usually divided into projection(primary and secondary) and associative. Projection centers- areas of the cortex that are the cortical part of a particular analyzer. The criterion for classifying centers as primary- the existence of direct input from the projection nuclei of the thalamus. They are characterized by a strict topological organization of inputs and a proportional dependence of the area of ​​representation on the density of innervation of the corresponding section of the prescription surface. The consequence of damage to the primary projection zone is loss of perception of stimuli arriving at the corresponding area of ​​the receptor surface.

Secondary zones are located near the primary projection centers and are their peripheral sections. They are characterized, in addition to direct inputs from the projection thalamic nuclei, inputs from the primary projection centers, as well as a predominant representation of the most intensively innervated, and therefore the most functionally important, departments. The role of secondary fields in the processes of perception and organization of movements turns out to be more complex compared to primary ones. Damage leads to disruption of complex forms of perception, recognition and evaluation of stimuli.

Association centers in the human brain they occupy more than half of the entire surface of the hemispheres of the Great Cretaceous and are the youngest formations. Associative centers are connected with the associative nuclei of the thalamus and with the projection centers of the cortex. Associative centers take part in the organization of complex forms of behavior and in the implementation of higher nervous activity. Anatomically and functionally, association centers are often asymmetrical.

Main projection centers are:

1. General Sensitivity Center(tactile, temperature, pain, conscious proprioceptive). Localized in the postcentral gyrus (fields 3 - primary zone; 1,2 - secondary zone). The fields are somatotopically organized. The trunk and lower limb are projected in the upper part of the postcentral gyrus, the upper limb is projected in the middle, and the head is projected in the lower part. Damage to the center is accompanied by loss of tactile, temperature, pain sensitivity and muscle-articular sensation on the opposite half of the body.

2. Motor Function Center occupies field 4 of the precentral gyrus (primary zone) and field 6 of the paracentral lobule (secondary zone). Here the analysis of proprioceptive stimulation is carried out. The pyramidal tracts originate from the neurons of the inner pyramidal layer. In field 4 there is a clear somatotopic organization - the “Penfield motor homunculus”. The body is projected “upside down” onto the cortex of the opposite hemisphere. Damage to the zone leads to impaired perception of proprioceptive stimuli, and central paralysis may occur. The center of motor functions is necessary to perform integrative functions when performing voluntary movements.

3. Body diagram center located in the parietal lobe (area 40). It presents somatotopic projections of all parts of the body. This is where conscious proprioceptive sensitivity comes in. The purpose of the center is to determine the position of the body and its parts in space and assess muscle tone. Violation of the center leads to the inability to recognize parts of one’s own body, a feeling of extra limbs, and a violation of the determination of the position of the body and its parts in space.

4. Center of vision located in the occipital lobe (field 17 - primary zone, fields 18, 19 - secondary). The retina is projected on the neurons of field 17. Neurons in field 18 provide visual memory, and field 19 provide orientation in an unusual environment. Unilateral damage to area 17 is accompanied by partial blindness in both eyes, but in different parts of the retina. Damage to fields 18 and 19 leads to distorted visual perception.

5. Hearing Center located in the superior temporal gyrus, on the surface facing the insula (area 41). This is the primary auditory center, unilateral damage to which leads to hearing loss in both ears, and to a greater extent on the opposite side. Bilateral damage leads to complete deafness.

6. Center of taste located on the medial surface of the temporal lobe (fields 11, A, E). This is where the fibers of the taste tract of one’s own and the opposite side end. These areas are classified as the limbic lobe of the brain, damage to which causes disturbances of taste, smell, and the appearance of hallucinations.

7. Olfactory center located in the same place as the projection center of taste. The fibers of the olfactory pathway of one’s own and the opposite side end here. Unilateral damage leads to decreased sense of smell and olfactory hallucinations.

8. Center for Vestibular Functions located on the dorsal surface of the temporal lobe (fields 20,21,22). Damage to these sections leads to spontaneous dizziness, a feeling of instability, a feeling of falling through, a feeling of deformation of surrounding objects and their movement.

9. The center of visceroreception occupies field 43 of the lower third of the postcentral and precentral gyri. Information comes here from the interoceptors of internal organs. The center analyzes mainly pain sensations.

Main association centers are:

1. Stereognosia Center(recognizing objects by touch). Located in the superior parietal lobe (area 7). The function of the center is to recognize previously encountered objects. The center is constantly developing. When the center is damaged, the ability to create a general holistic idea of ​​an object with closed eyes is lost, while individual properties (shape, texture, mass, temperature, etc.) are determined correctly.

2. Praxia Center(purposeful habitual movements). It is located in the inferior parietal lobule (area 40) in the left hemisphere of right-handers and in the right hemisphere of left-handers. Ambidexes (who have equal use of both hands) have a center in both hemispheres. The center develops as a result of repeated repetition of complex purposeful movements. Defeat leads to the loss of voluntary movements acquired through practice.

3. Visual Memory Center. It is located on the dorsal surface of the occipital lobe (areas 18-19) on the left in right-handers and on the right in left-handers. Provides memorization of objects by their shape, appearance, color. Damage to the center leads to visual agnosia. Partial agnosia may be observed (does not recognize friends, your home, or yourself in the photo).

Centers associated with speech function.

4. Acoustic speech center(Wernicke Center). Located in the area of ​​the superior temporal gyrus (area 42). Damage to the center leads to sensory aphasia (verbal deafness). Although the patient hears, he does not understand speech. Auditory control of one’s own speech is impaired, which leads to the inability to construct coherent sentences. The speech of such patients is a collection of meaningless words and sounds.

5. Motor speech center(Broca's center). It is located in the area of ​​the inferior frontal gyrus (field 44) ​​in right-handers - on the left, in left-handers - on the right. With damage, motor aphasia develops - the inability to speak while fully maintaining understanding and internal speech.

6. Singing Speech Analyzer Center. Located next to the previous one (central sections of the inferior frontal gyrus) (field 45). Damage to the center is accompanied by vocal amusia - the inability to perceive and compose musical phrases, and agrammatism - the inability to compose meaningful sentences from individual words. The speech of patients is an unrelated set of words.

7. Visual analyzer of written speech. Located in the angular gyrus of the inferior parietal lobule (area 39). The center analyzes visual information about letters, numbers, the composition of words and understands their meaning. Defeat leads to the inability to read - alexia. The patient sees the letters, but does not understand the meaning.

8. Motor analyzer of written speech. Occupies the posterior sections of the middle frontal gyrus (field 8). When the center is damaged, agraphia occurs (the inability to make precise and subtle movements with the hand necessary for writing).

These centers develop only in humans and are improved throughout life.

The auditory and motor centers of speech are formed at 3-4 months of life. The visual center of speech is in the fourth year of life. The motor center of writing begins to form at 5-6 years of age.

The cerebral cortex, subcortical structures, as well as peripheral components of the body are connected by neuronal fibers that form several types of pathways. Association fibers- pass within only one hemisphere and connect neighboring gyri in the form short arcuate fascicles, or the cortex of various lobes, which requires more long fibers The purpose of associative connections is to ensure the holistic functioning of one hemisphere as an analyzer and synthesizer of multimodal excitations. Projection fibers- connect peripheral structures with the cerebral cortex. Ascending pathways. - transmit information to the corresponding cortical representations of a particular analyzer. Descending fibers- begin from the motor areas of the brain. The task of these fibers is to organize motor activity. Commissural fibers- ensure holistic collaboration of the two hemispheres. They are presented alone