The main sulci and convolutions of the brain. Large hemispheres: lobes, sulci, gyri, gray and white matter. Cavity of the hemispheres Gyri and lobes of the outer surface of the cerebral hemisphere

Rice. 22. Grooves and convolutions on the superolateral surface.

1. central sulcus (Rolandova)
2. precentral sulcus and gyrus
3. superior frontal sulcus and gyrus
4. middle frontal gyrus
5. inferior frontal sulcus and gyrus
6. tire
7. triangular part
8. orbital surface
9. postcentral boron. and gyrus
10. intraparietal sulcus
11. superior parietal lobule
12. inferior parietal lobule
13. supramarginal gyrus
14. angular gyrus
15. lateral groove (Sylvia)
16. superior temporal sulcus and gyrus
17. middle temporal gyrus
18. inferior temporal sulcus and gyrus

Rice. 23. Grooves and convolutions on the medial surface

19. corpus callosum and its sulcus
20. gray matter of the corpus callosum
21. subcallosal area
22. peri-terminal gyrus
23. waist pine forest. and gyrus
24. isthmus of the cingulate gyrus
25. hippocampal sulcus (dentate gyrus)
26. paracentral lobule
27. precuneus
28. wedge
29. parieto-occipital sulcus
30. calcarine groove
31. lingular gyrus
32. parahippocampal sulcus and gyrus
33. hook
34. nasal groove
35. medial temporo-occipital
36. lateral temporo-occipital gyrus
37. temporo-occipital sulcus

The cerebral cortex is covered with grooves and convolutions (,,). The deepest primary grooves are distinguished, which divide the hemispheres into lobes. The lateral sulcus (Sylvius) separates the frontal lobe from the temporal lobe, the central sulcus (Rolandova) separates the frontal from the parietal. The parieto-occipital sulcus is located on the medial surface of the hemisphere and separates the parietal and occipital lobes; on the superolateral surface there is no clear boundary between these lobes.

On the medial surface there is a cingulate sulcus, which passes into the hippocampal sulcus, which limits the olfactory brain from the remaining lobes.

Secondary grooves are less deep; they divide the lobes into convolutions and are located outside the convolutions of the same name. Tertiary (innominate) grooves give the gyri an individual shape and increase the area of ​​their cortex.

The insular lobe is located in the depths of the lateral sulcus (). It is surrounded on three sides by a circular groove, its surface is indented with grooves and convolutions. Functionally, the insula is connected to the olfactory brain.

Fig.24. Furrows and convolutions of the lower surface of the cerebral hemispheres

1. olfactory groove
2. gyrus rectus
3. orbital grooves
4. orbital gyri (variable)
5. inferior temporal sulcus
6. parahippocampal (collateral) sulcus
7. parahippocampal gyrus
8. temporo-occipital sulcus
9. calcarine groove

General overview of the structure of the cerebral hemispheres

The cerebral hemispheres are the most massive part of the brain. They cover the cerebellum and brain stem. The cerebral hemispheres make up approximately 78% of the total brain mass. During the ontogenetic development of the organism, the cerebral hemispheres develop from the telencephalon of the neural tube, therefore this part of the brain is also called the telencephalon.

The cerebral hemispheres are divided along the midline by a deep vertical fissure into the right and left hemispheres.

In the depths of the middle part, both hemispheres are connected to each other by a large commissure - the corpus callosum. Each hemisphere has lobes; frontal, parietal, temporal, occipital and insula.

The lobes of the cerebral hemispheres are separated from one another by deep grooves. The most important are three deep grooves: the central (Rolandian) separating the frontal lobe from the parietal, the lateral (Sylvian) separating the temporal lobe from the parietal, the parieto-occipital separating the parietal lobe from the occipital on the inner surface of the hemisphere.

Each hemisphere has a superolateral (convex), inferior and internal surface.

Each lobe of the hemisphere has cerebral convolutions separated from each other by grooves. The top of the hemisphere is covered with a cortex - a thin layer of gray matter, which consists of nerve cells.

The cerebral cortex is the youngest formation of the central nervous system in evolutionary terms. In humans it reaches its highest development. The cerebral cortex is of great importance in the regulation of the body’s vital functions, in the implementation of complex forms of behavior and the development of neuropsychic functions.

Under the cortex is the white matter of the hemispheres; it consists of processes of nerve cells - conductors. Due to the formation of cerebral convolutions, the total surface of the cerebral cortex increases significantly. The total area of ​​the cerebral cortex is 1200 cm 2, with 2/3 of its surface located in the depths of the grooves, and 1/3 on the visible surface of the hemispheres. Each lobe of the brain has a different functional significance.

The frontal lobe occupies the anterior parts of the hemispheres. It is separated from the parietal lobe by the central sulcus, and from the temporal lobe by the lateral sulcus. The frontal lobe has four gyri: one vertical - the precentral and three horizontal - the superior, middle and inferior frontal gyri. The convolutions are separated from each other by grooves.

On the lower surface of the frontal lobes, the rectus and orbital gyri are distinguished. The gyrus recta lies between the inner edge of the hemisphere, the olfactory sulcus and the outer edge of the hemisphere.

In the depths of the olfactory sulcus lie the olfactory bulb and the olfactory tract.

The human frontal lobe makes up 25-28% of the cortex; the average weight of the frontal lobe is 450 g.

The function of the frontal lobes is associated with the organization of voluntary movements, motor mechanisms of speech, regulation of complex forms of behavior, and thinking processes. Several functionally important centers are concentrated in the convolutions of the frontal lobe. The anterior central gyrus is a “representation” of the primary motor zone with a strictly defined projection of body parts. The face is “located” in the lower third of the gyrus, the hand is in the middle third, the leg is in the upper third. The trunk is represented in the posterior parts of the superior frontal gyrus. Thus, a person is projected in the anterior central gyrus upside down and head down.

The anterior central gyrus, together with the adjacent posterior and parts of the frontal gyri, plays a very important functional role. It is the center of voluntary movements. In the depths of the cortex of the central gyrus, from the so-called pyramidal cells - the central motor neuron - the main motor path begins - the pyramidal, corticospinal path. The peripheral processes of motor neurons leave the cortex, gather into a single powerful bundle, pass through the central white matter of the hemispheres and enter the brain stem through the internal capsule; at the end of the brainstem they partially decussate (passing from one side to the other) and then descend into the spinal cord. These processes end in the gray matter of the spinal cord. There they come into contact with the peripheral motor neuron and transmit impulses from the central motor neuron to it. Impulses of voluntary movement are transmitted along the pyramidal pathway.

In the posterior sections of the superior frontal gyrus there is also an extrapyramidal center of the cortex, which is closely connected anatomically and functionally with the formations of the so-called extrapyramidal system. The extrapyramidal system is a motor system that assists in voluntary movement. This is a system for “providing” voluntary movements. Being phylogenetically older, the extrapyramidal system in humans provides automatic regulation of “learned” motor acts, maintenance of general muscle tone, readiness of the peripheral motor system to perform movements, and redistribution of muscle tone during movements. In addition, it is involved in maintaining normal posture.

The motor areas of the cortex are located mainly in the precentral gyrus and paracentral lobule on the medial surface of the hemisphere. Primary and secondary areas are distinguished. These fields are motor, but according to their characteristics, according to research from the Brain Institute, they are different. The primary motor cortex contains neurons that innervate the motor neurons of the muscles of the face, trunk and limbs.

It has a clear topographic projection of the muscles of the body. The main pattern of topographic representation is that the regulation of the activity of muscles that provide the most accurate and varied movements (speech, writing, facial expressions) requires the participation of large areas of the motor cortex. Field 4 is completely occupied by the centers of isolated movements, field 6 is only partially occupied.

The preservation of field 4 turns out to be necessary to obtain movements when both field 4 and field 6 are stimulated. In a newborn, field 4 is almost mature. Irritation of the primary motor cortex causes contraction of the muscles of the opposite side of the body (for the muscles of the head, the contraction can be bilateral). When this cortical zone is damaged, the ability to make fine coordinated movements of the limbs and especially the fingers is lost.

The secondary motor cortex has a dominant functional significance in relation to the primary motor cortex, carrying out higher motor functions associated with planning and coordination of voluntary movements. Here, the slowly increasing negative readiness potential, which occurs approximately 1 s before the start of movement, is most recorded. The cortex of area 6 receives the bulk of impulses from the basal ganglia and cerebellum and is involved in the recoding of information about complex movements.

Irritation of the cortex of area 6 causes complex coordinated movements, for example, turning the head, eyes and torso in the opposite direction, cooperative contractions of the flexors or extensors on the opposite side. In the premotor cortex there are motor centers associated with human social functions: the written speech center in the posterior part of the middle frontal gyrus, the Broca motor speech center in the posterior part of the inferior frontal gyrus, which provides speech, as well as the musical motor center, which provides the tone of speech and the ability to sing. The lower part of field b (subfield boron), located in the area of ​​the tire, reacts to the electric current with rhythmic chewing movements. Neurons of the motor cortex receive afferent inputs through the thalamus from muscle, joint and skin receptors, from the basal ganglia and cerebellum. The main efferent output of the motor cortex to the stem and spinal motor centers are the pyramidal cells of layer V.

In the posterior part of the middle frontal gyrus there is the frontal oculomotor center, which controls the concomitant, simultaneous rotation of the head and eyes (the center of rotation of the head and eyes in the opposite direction). Irritation of this center causes the head and eyes to turn in the opposite direction. The function of this center is of great importance in the implementation of the so-called orientation reflexes (or “what is this?” reflexes), which are very important for preserving the life of animals.

The frontal cortex of the cerebral hemispheres also takes an active part in the formation of thinking, the organization of purposeful activities, and long-term planning.

The parietal lobe occupies the superior lateral surfaces of the hemisphere. From the frontal lobe, the parietal lobe is limited in front and to the side by the central sulcus, from the temporal lobe below - by the lateral sulcus, from the occipital - by an imaginary line running from the upper edge of the parieto-occipital sulcus to the lower edge of the hemisphere.

On the superolateral surface of the parietal lobe there are three gyri: one vertical - posterior central and two horizontal - superior parietal and inferior parietal. The part of the inferior parietal gyrus, which encircles the posterior part of the lateral sulcus, is called the supramarginal (supramarginal) region, the part surrounding the superior temporal gyrus is the nodal (angular) region.

The parietal lobe, like the frontal lobe, makes up a significant part of the cerebral hemispheres. In phylogenetic terms, it is divided into an old section - the posterior central gyrus, a new one - the superior parietal gyrus and a newer one - the inferior parietal gyrus.

The function of the parietal lobe is associated with the perception and analysis of sensory stimuli and spatial orientation. Several functional centers are concentrated in the gyri of the parietal lobe.

In the posterior central gyrus, sensitivity centers are projected with a body projection similar to that in the anterior central gyrus. The face is projected in the lower third of the gyrus, the arm and torso are projected in the middle third, and the leg is projected in the upper third. In the superior parietal gyrus there are centers in charge of complex types of deep sensitivity: muscular-articular, two-dimensional spatial sense, a sense of weight and range of motion, a sense of recognizing objects by touch.

Posterior to the upper parts of the posterior central gyrus, a center is located that provides the ability to recognize one’s own body, its parts, their proportions and relative positions.

Fields 1, 2, 3 of the postcentral region constitute the main cortical nucleus of the skin analyzer. Together with field 1, field 3 is the primary, and field 2 is the secondary projection zone of the skin analyzer. The postcentral region is connected by efferent fibers to the subcortical and stem formations, to the precentral and other areas of the cerebral cortex. Thus, the cortical section of the sensitive analyzer is localized in the parietal lobe.

Primary sensory zones are areas of the sensory cortex, irritation or destruction of which causes clear and permanent changes in the sensitivity of the body (analyzer nuclei, according to I.P. Pavlov). They consist mainly of unimodal neurons and form sensations of the same quality. In the primary sensory zones there is usually a clear spatial (topographic) representation of body parts and their receptor fields.

Around the primary sensory zones there are less localized secondary sensory zones, the neurons of which respond to the action of several stimuli, i.e. they are multimodal.

The most important sensory area is the parietal cortex of the postcentral gyrus and the corresponding part of the paracentral lobule on the medial surface of the hemispheres, which is designated as somatosensory area I. Here there is a projection of the skin sensitivity of the opposite side of the body from tactile, pain, temperature receptors, interoceptive sensitivity and sensitivity of the musculoskeletal system - from muscle, joint, tendon receptors.

In addition to somatosensory area I, a smaller somatosensory area II is distinguished, located at the border of the intersection of the central sulcus with the upper edge of the temporal lobe, in the depth of the lateral sulcus. The degree of localization of body parts is less pronounced here.

Praxis centers are located in the inferior parietal lobe. Praxis refers to purposeful movements that have become automated in the process of repetition and exercise, which are developed in the process of learning and constant practice throughout an individual’s life. Walking, eating, dressing, the mechanical element of writing, various types of work activities (for example, the movements of a driver while driving a car, mowing, etc.) are praxis. Praxis is the highest manifestation of the motor function inherent in humans. It is carried out as a result of the combined activity of various areas of the cerebral cortex.

In the lower parts of the anterior and posterior central gyri there is the center of the analyzer of interoceptive impulses of internal organs and blood vessels. The center has close connections with subcortical vegetative formations.

The temporal lobe occupies the inferolateral surface of the hemispheres. From the frontal and parietal lobes, the temporal lobe is limited by the lateral sulcus. On the superolateral surface of the temporal lobe there are three gyri: superior, middle and inferior.

The superior temporal gyrus is located between the Sylvian and superior temporal fissures, the middle one is between the superior and inferior temporal sulci, and the inferior one is between the inferior temporal sulcus and the transverse medullary fissure. On the lower surface of the temporal lobe, the inferior temporal gyrus, the lateral occipitotemporal gyrus, and the hippocampal gyri (seahorse leg) are distinguished.

The function of the temporal lobe is associated with the perception of auditory, gustatory, olfactory sensations, analysis and synthesis of speech sounds, and memory mechanisms. The main functional center of the superior lateral surface of the temporal lobe is located in the superior temporal gyrus. The auditory, or gnostic, speech center (Wernicke's center) is located here.

A well-studied primary projection zone is the auditory cortex, which is located deep in the lateral sulcus (cortex of Heschl's transverse temporal gyri). The projection cortex of the temporal lobe also includes the center of the vestibular analyzer in the superior and middle temporal gyri.

The olfactory projection area is located in the hippocampal gyrus, especially in its anterior section (the so-called uncus). Next to the olfactory projection zones are the gustatory zones.

The temporal lobes play an important role in organizing complex mental processes, in particular memory.

The occipital lobe occupies the posterior parts of the hemispheres. On the convex surface of the hemisphere, the occipital lobe has no sharp boundaries separating it from the parietal and temporal lobes, with the exception of the upper part of the parieto-occipital sulcus, which, located on the inner surface of the hemisphere, separates the parietal lobe from the occipital lobe. The grooves and convolutions of the superolateral surface of the occipital lobe are not constant and have a variable structure. On the inner surface of the occipital lobe there is a calcarine groove that separates the cuneus (a triangular lobule of the occipital lobe) from the lingual gyrus and the occipitotemporal gyrus.

The function of the occipital lobe is associated with the perception and processing of visual information, the organization of complex processes of visual perception - in this case, the upper half of the retina is projected in the wedge area, which perceives light from the lower fields of vision; in the region of the lingular gyrus there is the lower half of the retina of the eye, which perceives light from the upper fields of vision.

The primary visual area is located in the occipital cortex (the cortex of part of the sphenoid gyrus and the lingual lobule). Here there is a topical representation of retinal receptors. Each point of the retina corresponds to its own section of the visual cortex, while the macula zone has a relatively large area of ​​representation. Due to the incomplete decussation of the visual pathways, the same halves of the retina are projected into the visual area of ​​each hemisphere. The presence of a retinal projection in both eyes in each hemisphere is the basis of binocular vision. The cortex of the secondary visual area is located near area 17. The neurons of these zones are multimodal and respond not only to light, but also to tactile and auditory stimuli. In this visual area, various types of sensitivity are synthesized, more complex visual images arise and their recognition is carried out.

The island, or the so-called closed lobule, is located in the depths of the lateral sulcus. The insula is separated from adjacent neighboring sections by a circular groove. The surface of the insula is divided by its longitudinal central groove into anterior and posterior parts. A taste analyzer is projected in the island.

Limbic cortex. On the inner surface of the hemispheres above the corpus callosum is the cingulate gyrus. This gyrus passes through the isthmus behind the corpus callosum into the gyrus near the seahorse - the parahippocampal gyrus. The cingulate gyrus, together with the parahippocampal gyrus, makes up the vaulted gyrus.

The limbic cortex is united into a single functional system - the limbic-reticular complex. The main function of these parts of the brain is not so much to provide communication with the outside world, but to regulate the tone of the cortex, drives and affective life. They regulate complex, multifaceted functions of internal organs and behavioral reactions. The limbic-reticular complex is the most important integrative system of the body. The limbic system is also important in the formation of motivation. Motivation (or internal drive) includes complex instinctive and emotional reactions (food, defensive, sexual). The limbic system is also involved in the regulation of sleep and wakefulness.

The limbic cortex also performs an important function of smell. The sense of smell is the perception of chemicals in the air. The human olfactory brain provides the sense of smell, as well as the organization of complex forms of emotional and behavioral reactions. The olfactory brain is part of the limbic system.

The corpus callosum is an arcuate thin plate, phylogenetically young, connecting the median surfaces of both hemispheres. The elongated middle part of the corpus callosum at the back becomes thickened, and at the front it bends and bends downward in an arched manner. The corpus callosum connects the phylogenetically youngest parts of the hemispheres and plays an important role in the exchange of information between them.

Telencephalon: grooves and convolutions of the superolateral surface of the cerebral hemispheres.

External structure of the cerebral hemispheres, lobes of the cerebral hemispheres, insula.

telencephalon, telencephalon g consists of two hemispheres, each of which contains gray matter (cortex and basal ganglia), white matter and the lateral ventricle. Hemisphere of the brain, hemispherium cerebralis, has three surfaces: upper lateral, medial and lower (Facies superlateralis hemispherii cerebri. Facies medialis hemispherii cerebri. Facies inferior hemispherii cerebri). These surfaces are separated from each other by edges: superior, inferolateral and inferomedial (Margo superior. Margo inferolateralis. Margo inferomedialis). Each hemisphere has 5 lobes, in which there are grooves, sulci, and roller-like elevations located between them - convolutions, gyri. Frontal lobe, lobus frontalis, separated from below from the temporal lobe, lobus temporalis, lateral (Sylvian) fissure, sulcus lateralis, from the parietal central (Rolandic) fissure, sulcus centralis. , from the occipital lobe, lobus occipitalis, separated by the parieto-occipital groove, sulcus parietooccipitalis. The protruding parts of the three lobes of the hemispheres are called the frontal, occipital and temporal poles (Polus frontalis. Polus occipitalis. Polus temporalis). Fifth beat - o the insular lobe (islet), lobus insularis (insula), is not visible from the outside. This lobe can only be seen if the frontal and frontoparietal operculum are removed. The insula is separated from the adjacent parts of the brain by the circular groove of the insula, sulcus circularis insulae. On its surface there are long and short convolutions, gyri insulae longus et breves. Between the long groove located in the posterior part of the insula and the anterior grooves located in the anterior part, there is the central groove of the insula, sulcus centralis insulae. The anteroinferior part of the insula is thickened - it is called the threshold of the insula, limen insulae.

Fissures and convolutions of the superolateral surface within the frontal lobe

Frontal lobe, lobus frontalis, separated from the temporal lobe by the lateral groove, sulcus lateralis. In the anterior section, the lateral groove expands in the form of the lateral fossa, fossa lateralis cerebralis. Posteriorly, the frontal lobe is separated from the parietal central sulcus, sulcus centralis. Anterior to the central sulcus, parallel to it, is the precentral sulcus, sulcus precentralis. The furrow may consist of two parts. Between these grooves is the precentral gyrus, gyrus precentralis. The superior and inferior frontal sulci, sulci frontales superior et inferior, extend forward from the precentral sulcus. Medial between these grooves is the middle frontal gyrus, gyrus frontalis medius. Medial to the superior frontal sulcus is the superior frontal gyrus, gyrus frontalis superior, lateral to the inferior frontal sulcus is the inferior frontal gyrus, gyrus frontalis inferior. In the posterior part of this gyrus there are two small grooves: the ascending branch, ramus ascendens, and the anterior branch, ramus anterior, which adjoin at an angle to the lateral sulcus and divide the inferior frontal gyrus into three parts: tegmental, triangular and orbital. Tegmental part (frontal operculum), pars opercularis (operculum frontale). Triangular part, pars triangularis. Orbital part, pars orbitalis.

Fissures and convolutions of the superolateral surface within the parietal lobe

Parietal lobe, lobus parietalis, is separated from the occipital lobe by the parieto-occipital groove, sulcus parietooccipitalis, which is well defined on the medial surface of the hemisphere. It deeply dissects the upper edge of the hemisphere and passes to its superolateral surface. On this surface the groove is not always well defined, so it is usually continued in the form of a conventional line in the lower direction. In the parietal lobe there is a postcentral sulcus, sulcus postcentralis, running parallel to the central one. Between them is the postcentral gyrus, gyrus postcentralis. On the medial surface of the hemisphere, this gyrus connects with the precentral gyrus of the frontal lobe. These parts of both gyri form the paracentral lobule, lobulus paracentralis. On the superolateral surface of the parietal lobe, the intraparietal groove, sulcus intraparietalis, extends parallel to the upper edge of the hemispheres. Above it lies the superior parietal lobule, lobulus parietalis superior; below and lateral to this groove is the inferior parietal lobule, lobulus parietalis inferior. Within this lobule there are two gyri: supramarginal, gyrus supramarginalis (around the terminal section of the lateral sulcus), and angular, gyrus angularis (around the terminal section of the superior temporal gyrus). The anterior part of the inferior parietal lobule, together with the lower sections of the post- and precentral gyri, are united under the general name of the frontoparietal operculum of the insula, operculum frontoparietale. This tegmentum, together with the frontal tegmentum, hangs over the insula, making it invisible from the superolateral surface.

Furrows and convolutions of the superolateral surface within the temporal and occipital lobes

Temporal lobe, lobus temporalis separated from the described lobes of the hemisphere by a deep lateral sulcus. The portion of the lobe covering the insula is called the temporal operculum, operculum temporale. In the temporal lobe, in the lower direction, parallel to the lateral sulcus, there are the superior and inferior temporal sulci, sulci superior et inferior, between which is the middle temporal gyrus, gyrus temporalis medius. Between the superior temporal and lateral gyri the superior temporal gyrus, gyrus temporalis superior, is localized. On the upper surface of the gyrus, facing the island in the depth of the lateral sulcus, there are two or three short transverse temporal gyri (Heschl’s gyri), gyri temporales transversi. Between the inferior temporal sulcus and the inferolateral edge of the hemisphere, within the temporal lobe, there is the inferior temporal gyrus, gyrus temporalis inferior, the posterior section of which passes into the occipital lobe.

Occipital lobe, lobus occipitalis. The lobe relief on the superolateral surface is very variable. Most often present is the transverse occipital sulcus, sulcus occipitalis transversus, which can be imagined as a continuation towards the occipital pole of the intraparietal sulcus.

Telencephalon: grooves and convolutions of the medial and inferior surfaces of the cerebral hemispheres.

The concept of the analyzer according to Pavlov I.P., the cortex as a set of cortical ends of the analyzers

I.P. Pavlov considered the cerebral cortex as a huge perceptive surface (450,000 mm 2), as a collection of cortical ends of analyzers. The analyzer consists of three parts: 1) peripheral, or receptor, 2) conductive and 3) central, or cortical. The cortical part (end of the analyzer) has a core and periphery. Neurons belonging to a specific analyzer are concentrated in the nucleus. It is where the highest analysis and synthesis of information from receptors takes place. The periphery does not have clear boundaries, the cell density is lower, here the nuclei overlap each other. They carry out simple, elementary analysis and synthesis of information. Ultimately, at the cortical end of the analyzer, based on the analysis and synthesis of incoming information, responses are developed that regulate all types of human activity.

Limbic system

This is a set of formations of the telencephalon, diencephalon and midbrain. In the phylogenesis of this system, the sense of smell played an important role, therefore, the main structures of the limbic system are located within the medial surface of the cerebral hemispheres. The cortical formations of this system include the central part of the olfactory brain, rhinencephalon, which includes: the vaulted gyrus, the uncus, the dentate gyrus, the hippocampus, as well as the peripheral part of the olfactory brain, consisting of: the olfactory bulb, the olfactory tract, the olfactory triangle, the anterior perforated substance. The limbic system also includes subcortical formations: the basal ganglia, the septum pellucidum, some nuclei of the thalamus, hypothalamus and the reticular formation of the midbrain. Functions of the limbic system. It ensures the interaction of extero- and interoceptive influences and the development of responses to them from the autonomic nervous system, affecting the functioning of the respiratory, cardiovascular and other systems, and thermoregulation. It regulates the most general states of the body (sleep, wakefulness, expression of emotions, motivation). With all these reactions, the emotional state actively changes, indicating the interaction of the limbic system with the cerebral cortex.

176. Lateral ventricle of the cerebral hemispheres: sections, their walls. Cerebrospinal fluid, its formation and outflow pathways.

Walls of the lateral ventricle

Medial - Hippocampus and Fimbria hippocampi

Cerebrospinal fluid, its formation and outflow pathways.

Cerebrospinal fluid, liquor cerebrospinalis. Liquor is one of the biological fluids of the body, located in all cavities of the central nervous system (ventricles of the brain and the central canal of the spinal cord), in the subarachnoid and perineural spaces. Cerebrospinal fluid is formed as a result of ultrafiltration of blood plasma through the wall of the capillaries of the plexus choroideus III, IV and lateral ventricles and the activity of ependymal cells lining all cavities of the central nervous system. The total volume of cerebrospinal fluid is approximately 150 ml. Cerebrospinal fluid is constantly formed and flows in certain directions depending on the location (CNS cavity). From the lateral ventricles, cerebrospinal fluid enters the third ventricle through the interventricular foramina, and from it through the cerebral aqueduct into the fourth ventricle. CSF also flows into it from the central canal of the spinal cord. From the cavity of the fourth ventricle, cerebrospinal fluid is directed through two lateral and median apertures into the subarachnoid space. From there it is filtered through the granulations of the arachnoid membrane (Pachionian granulations) into the venous blood of the sinuses of the dura mater of the brain. In this way, up to 40% of the cerebrospinal fluid flows away. Approximately 30% of cerebrospinal fluid drains into the lymphatic system through the perineural spaces of the spinal and cranial nerves. The remaining volume of cerebrospinal fluid is resorbed by the ependyma, and also sweats into the subdural space, and then is absorbed into the capillary vessels of the dura mater of the brain. Liquor has a relatively constant composition and is renewed 5–8 times during the day. If necessary, cerebrospinal fluid is most often taken through puncture of the subarachnoid space of the spinal cord between the II and III lumbar vertebrae.

The wall of the blood capillaries of the brain and especially the choroid plexuses of the ventricles of the brain on the one hand, cerebrospinal fluid and nervous tissue on the other, form the blood-brain barrier. This barrier prevents the penetration of certain substances and microorganisms from the blood into the brain tissue.

Functions of cerebrospinal fluid:

1. Protects the SM and GM from mechanical influences during movement.

1. Ensures the constancy of the internal environment of the body.
2. Participates in the trophism of nervous tissue.
3. Takes part in neurohumoral regulation.
4. Used for diagnostic and therapeutic purposes.

Epithalamus and metathalamus

Epithalamus (suprathalamic, supratuberous region), epithalamus, consists of 5 small formations. The largest of them is the pineal body (pineal gland, epiphysis cerebri), corpus pineale (glandula pinealis, epiphysis cerebri), weighing 0.2 g. It is located in the groove between the superior colliculi of the midbrain. Through the leashes, habenulae, the epithalamus is connected to the visual tuberosities. In these places there are extensions - this is the leash triangle, trigonum habenulae. The parts of the leashes included in the epithalamus form the commissure of the leashes, comissura habenularum. Below the epithalamus there are transversely located fibers - the epithalamic commissure, comissura epithalamica. Between it and the commissure of the leashes, a pineal-shaped depression, recessus pinealis, protrudes into the epithalamus.

Metathalamus (zathalamic, foreign region), metathalamus, represented by paired medial and lateral geniculate bodies. The lateral geniculate body, corpus geniculatum laterale, is located on the side of the optic thalamus cushion. The fibers of the optic tract enter it. Through the handles of the superior colliculi, the lateral geniculate bodies are connected to the superior colliculi; the lateral geniculate bodies and the superior colliculi of the midbrain are the subcortical centers of vision. Under the pillow are the medial geniculate bodies, corpus geniculatum mediale, which are connected to the lower colliculi by means of handles. The fibers of the lateral auditory lemniscus end here, the medial geniculate bodies and the inferior colliculi end as subcortical hearing centers.

Hypothalamus

Hypothalamus (subthalamic, subcutaneous region), hypothalamus, includes the lower parts of the diencephalon: optic chiasm, optic tracts, gray tubercle, infundibulum, pituitary gland and mastoid bodies. The optic chiasm, chiasma opticum, is formed by the medial fibers of the nn. optici, which move to the opposite side and become part of the visual tract, tractus opticus. The tracts are located medial and posterior to the anterior perforated substance, bend around the cerebral peduncle from the lateral side and enter the subcortical centers of vision with two roots: the lateral root enters the lateral geniculate body, and the medial root enters the superior colliculus of the roof of the midbrain.

The gray tubercle, tuber cinereum, is located behind the optic chiasm. The lower part of the tubercle looks like a funnel, infundibulum, on which the pituitary gland is suspended. The vegetative nuclei are localized in the gray mound.

The pituitary gland, hypophysis, is located in the sella turcica of the body of the sphenoid bone, has a bean-shaped shape and weighs 0.5 g. The pituitary gland, like the epiphysis, belongs to the endocrine glands.

The mastoid bodies, corpora mamillaria, are white, have a spherical shape, their diameter is about 0.5 cm. Inside the mastoid bodies are the subcortical nuclei (centers) of the olfactory analyzer.

The hypothalamus has more than 30 nuclei. Neurons of many nuclei produce neurosecretion, which is transported along the processes of neurons to the pituitary gland. These nuclei are called neurosecretory. All of the mentioned nuclei belong to the higher vegetative centers and have extensive nervous and humoral connections with the pituitary gland, which gave rise to combining them into the hypothalamic-pituitary system.

Isthmus of the rhombencephalon

Isthmus of the rhombencephalon, isthmus rhombencephali. It includes three structures located on the border of the midbrain and rhombencephalon:

1. Superior cerebellar peduncles, pedunculi cerebellares superiores. They contain the anterior spinocerebellar tracts.

2. Superior medullary velum, velum medullare superius. It is represented by a thin plate of white matter, which is attached to the superior cerebellar peduncles, the cerebellar vermis, and the roof of the midbrain through the frenulum of the superior medullary velum. On the sides of the frenulum emerge the roots of the fourth pair of cranial nerves, trochlear, n. trochlearis.

3. Loop triangle, trigonum lemnisci. It is localized in the lateral part of the isthmus, has a gray color and is limited in front by the handle of the lower colliculus, brachium colliculi inferioris; laterally – by the lateral groove of the midbrain, sulcus lateralis mesencephali; medially - the superior cerebellar peduncle.

Within the loop triangle there are structures of the hearing analyzer: the lateral lemniscus and the nuclei of the lateral lemniscus.

Brain stems

Brain peduncles, pedunculi cerebri, are located in front of the bridge in the form of thick ridges, each of which enters the corresponding hemisphere. Between the legs there is an interpeduncular fossa, fossa interpeduncularis, the bottom of which is called the posterior perforated substance, substantia perforata posterior, which serves for the passage of blood vessels. On the medial surface of the cerebral peduncles emerge the roots of the third pair of cranial nerves, n. oculomotorius.

A frontal section of the cerebral peduncle shows a black substance, substantia nigra, separating the tegmentum, tegmentum, from the base of the cerebral peduncle, basis pedunculi cerebri. The substantia nigra extends from the pons to the diencephalon. In the tire from the lower colliculi to the visual hillocks there is a red nucleus, nucleus ruber. The substantia nigra and red nucleus belong to the extrapyramidal system. The tegmentum contains ascending (sensitive) pathways as part of the medial and lateral loops. At the base of the legs, only descending (motor) pathways are localized: occipitotemporal-parietopontine, corticospinal, corticonuclear, frontopontine. From the tegmentum of the midbrain and the red nucleus, two extrapyramidal tracts begin: the roof-spinal cord and the red nucleus-spinal cord. In the tegmentum of the cerebral peduncles dorsal to the nuclei nn. Oculomotorii contains the nucleus of the medial longitudinal fasciculus, fasciculus longitudinalis medialis. It runs along the cerebral aqueduct and connects the nuclei of the III, IV, VI, VIII, XI pairs of cranial nerves with the motor cells of the anterior horns of the cervical segments of the spinal cord. This connection determines combined movements, as well as combined movements when the receptors of the vestibular analyzer are stimulated. Within the midbrain there are also structures of the reticular formation.

Reticular formation.

Reticular formation , formatio reticularis, represented by more than 100 nuclear clusters of neurons connected in different directions by many nerve fibers. Located in the brain stem, as well as between the lateral and posterior columns of the spinal cord. Neurons of the reticular formation have features: their dendrites are weakly branched, and their axons have numerous branches, thanks to which each of the neurons comes into contact with a huge number of other neurons. Neurons of the reticular formation are located between the ascending and descending pathways and have extensive connections with all parts of the central nervous system, including the cerebral cortex.

One of the functional features of the reticular formation is that its neurons are capable of being excited by nerve impulses coming from receptors of different sensory organs or different parts of the central nervous system, i.e. due to the convergence (convergence) of nerve impulses from various sources. Another functional feature of the reticular formation is that the excitation that arises in any group of neurons spreads relatively evenly to the overwhelming number of other neurons, and in its nature this excitation becomes homogeneous, regardless of the type of the original source of excitation (receptor) and the specific characteristics of the energy irritant. The function of the reticular formation is that it exerts an activating effect on the cerebral cortex, on all other parts of the central nervous system and sensory organs, maintaining a high level of their energy potential. It ensures the preservation of the automaticity of the activity of vital respiratory and cardiovascular centers in various functional states of the body, and promotes the development of conditioned reflexes.

GM dura shell

The outer layer of the brain, dura mater encephali (pachymeninx), is represented by dense connective tissue. The outer layer of the shell is adjacent to the bones of the brain skull and is their periosteum, and the inner layer faces the arachnoid membrane and is covered with endothelium. The dura mater of the brain has several processes located between certain parts of the brain:

1. The falx cerebri, falx cerebri, is a plate of the dura mater between the hemispheres of the cerebrum.

2. The tentorium (tent) of the cerebellum, tentorium cerebelli, is located above the cerebellum in the transverse fissure of the cerebrum. The tentorium separates the occipital lobes of the cerebral hemispheres from the cerebellum.

3. The falx of the cerebellum, falx cerebelli, is located between its hemispheres behind and above. The posterior edge of the falx is attached to the crista occipitalis interna; at its base is the occipital sinus.

4. The sella diaphragm, diaphragma sellae, is represented by a horizontal plate stretched over the pituitary fossa. Below the diaphragm is the pituitary gland. A funnel passes through a hole in the center of the diaphragm.

Commissural fibers

The most powerful commissural structure is the corpus callosum, corpus callosum, in which there is a knee, genu, beak, rostrum, which passes into the terminal plate, lamina terminalis; middle part – trunk, truncus; and the most posterior section is the splenium. Fibers running transversely in the corpus callosum in each hemisphere form the radiance of the corpus callosum, radiatio corporis callosi. The trunk fibers provide communication between the gray matter of the parietal and temporal lobes, the splenium connects the occipital lobes, and the genu connects the frontal lobes. Between the corpus callosum and the fornix there is a transparent septum, septum pellucidum, it consists of two thin plates, lamina septi pellucidi, fixed in front to the beak, knee and body of the corpus callosum (above), and behind - to the body and column of the corpus callosum. Between the transparent plates there is a slit-like cavity of the transparent septum, cavum septi pellucidi. The plates of the septum pellucidum are the medial walls of the right and left anterior horns of the lateral ventricles.

The commissural fibers include four more formations: The anterior commissure, comissura anterior (rostralis), lies in front of the columns of the fornix, connects the olfactory areas of the hemispheres and the parahippo-campal gyri. The fibers of the anterior part of the commissure connect the gray matter of the olfactory triangles of both hemispheres, and the fibers of the posterior part of the commissure - cortex of the anteromedial temporal lobes. Adhesion of leashes, comissura habenularum binds leashes. Epithalamic commissure, comissura epithalamica (posterior). The commissure of the fornix, comissura fornicis, connects the legs of the fornix posteriorly.

Association fibers

Short associative pathways in the form of arcuate fascicles, fibrae arcuatae cerebri, connect areas of the cortex of neighboring gyri with each other, long associative pathways connect areas of the cortex of the lobes of the hemispheres. The cortex of the frontal lobe communicates with the cortex of the parietal, occipital lobes and the posterior part of the temporal lobe through the superior longitudinal fasciculus, fasciculus longitudinalis superior. The cortical zones of the temporal and occipital lobes are connected by the lower longitudinal fasciculus, fasciculus longitudinalis inferior. The cortex of the orbital surface of the frontal lobe is connected with the cortex of the pole of the temporal lobe by the uncinate fasciculus, fasciculus uncinatus. A bundle of fibers called the cingulum, passing into the vaulted gyrus, gyrus fornicatus, connects sections of the cingulate gyrus both with each other and with neighboring gyri of the medial surface of the hemispheres.

Inner capsule

One group of commissural fibers runs from the cortical and basal ganglia of the hemispheres to the brain stem and spinal cord. Other fibers follow in the opposite direction. These two groups of fibers form the internal capsule and corona radiata in each hemisphere. The internal capsule, capsula interna, is located between the lentiform nucleus, the head of the caudate nucleus (anterior) and the thalamus (posterior). The capsule contains the anterior leg, crus anterior capsulae internae, the posterior leg, crus posterior capsulae internae, and the knee of the internal capsule, genu capsulae internae. The anterior leg contains the frontothalamic and frontopontine tracts, tr. frontothalamicus et frontopontinus, connecting the frontal cortex with the thalamus and pons. In the knee of the internal capsule there is a corticonuclear tract, tr. corticonuclearis. The posterior leg contains fibers of the corticospinal tract, tr. corticospinalis, thalamocortical fibers, tr. thalamocorticalis, corticothalamic tract, tr. corticothalamicus, parietooccipitopontinus, auditory and visual pathways, radiatio acustica et optica, going from the subcortical centers of hearing and vision to the cortical nuclei of these analyzers. The corona radiata, corona radiata, consists of fibers of ascending pathways that fan out to different parts of the cerebral cortex. Among these fibers, fibers pass in a descending direction into the cerebral peduncles.

Retina

The retina (the inner, sensitive shell of the eyeball), retina, tunica interna (sensoria) bulbi, has two layers: the outer pigment part, pars pigmentosa, and the inner light-sensitive, called the nervous part, pars nervosa. By function, the large posterior visual part of the retina is distinguished, pars optica retinae, containing sensitive elements - rods and cones, and the smaller “blind” part of the retina, devoid of rods and cones, combining the ciliary and iris parts of the retina, pars ciliaris et iridica retinae. The border between the visual and the “blind” parts is the serrated edge, ora serrata. It corresponds to the place of transition of the choroid proper into the ciliary circle, orbiculus ciliaris of the choroid.

At the bottom of the eyeball there is a whitish spot with a diameter of about 1.7 mm - the optic disc, discus nervi optici, with raised edges and a small depression, excavatio disci in the center. This is the place where the optic nerve fibers exit the eyeball, it does not have light-sensitive cells and is called the blind spot. In the center of the disk, the central artery, a.centralis retinae, entering the retina is visible. 4 mm lateral to the disc, at the level of the posterior pole of the eye, there is a yellowish spot, the macula, with a small depression - the central fovea, fovea centralis. This is the place of best vision, only cones are concentrated here.

Muscles of the eyeball.

There are six muscles of the eyeball: four rectus (superior, inferior, lateral and medial) and two oblique (superior and inferior). All rectus muscles and the superior oblique begin in the depths of the orbit from the common tendon ring, anulus tendineus communis, fixed to the sphenoid bone and periosteum around the optic canal, and partially from the edges of the superior orbital fissure. The ring surrounds the optic nerve and the ophthalmic artery, from which the muscle that lifts the upper eyelid, m. levator palpebrae superioris The rectus muscles pierce the vagina of the eyeball, vagina bulbi, and with short tendons are woven into the sclera in front of the equator, retreating 5-8 mm from the edge of the cornea. Lateral and medial rectus muscles, mm. recti lateralis et medialis, turn the eyeball in their direction. Superior and inferior rectus muscles, mm. recti superior et inferior, turn the eyeball upward and somewhat outward and downward and inward, respectively. Superior oblique muscle, m. obliquus superior, has a thin round tendon that extends over the trochlea, the trochlea, built in the form of a ring of fibrous cartilage, turns the eyeball down and laterally. Inferior oblique muscle, m. obliquus inferior, starts from the orbital surface of the upper jaw near the opening of the nasolacrimal canal, turns the eyeball upward and laterally.

Eyelids.

At the border of the upper eyelid and forehead, a skin covered with hair protrudes - the eyebrow, supercilium. The upper and lower eyelids, palpebra superior et inferior, have a front surface of the eyelid, facies anterior palpebrae, covered with thin skin with short vellus hair, sebaceous and sweat glands, and a back surface, facies posterior palpebrae, facing the eyeball, covered with conjunctiva, tunica conjuctiva . In the thickness of the eyelids there is a connective tissue plate - the upper eyelid cartilage, tarsus superior, and the lower eyelid cartilage, tarsus interior, as well as the age-old part of the orbicularis oculi muscle. From the upper and lower cartilages of the eyelids to the anterior and posterior lacrimal ridges, the medial ligament of the eyelid, ligamenturn palpebrale mediale, is directed, covering the lacrimal sac in front and behind. To the lateral wall of the orbit from the cartilages follows the lateral ligament of the eyelid, ligamentum palpebrale laterale, which corresponds to the lateral suture, raphe palpebralis lateralis. The tendon of the levator palpebrae superioris muscle is attached to the cartilage of the upper eyelid. The free edge of the eyelid forms the anterior and posterior edges of the eyelids, limbi palpebrales anterior et posterior and bears the eyelashes, cilia. Closer to the posterior edge, the openings of the modified sebaceous (meibomian) glands of the cartilage of the eyelids, glandulae tarsales, open. The edges of the eyelids limit the transverse palpebral fissure, rima palpebrarum, which is closed by the fusions of the eyelids - the medial and lateral commissures of the eyelids, comissura palpebralis medialis et lateralis.

Conjunctiva.

The conjunctiva, tunica conjunctiva, is a connective tissue membrane. It contains the conjunctiva of the eyelids, tunica conjunctiva palperarum, and the conjunctiva of the eyeball, tunica conjunctiva bulbaris. At the point of their transition into each other, depressions are formed - the upper and lower fornix of the conjunctiva, fornix conjunctive superior et inferior. The entire space limited by the conjunctiva is called the conjunctival sac, saccus conjunctivae. The lateral angle of the eye, angulus oculi lateralis, is more acute. The medial corner of the eye, angulus oculi medialis, is rounded and on the medial side it limits the depression - the lacrimal lake, lacus lacrimalis. There is also a small elevation here - the lacrimal caruncle, caruncula lacrimalis, and lateral to it - the semilunar fold of the conjunctiva, pilca semilunaris conjunctivae. On the free edge of the upper and lower eyelids, near the medial corner of the eye, there is a lacrimal papilla, papilla lacrimalis, with an opening at the top - the lacrimal punctum, punctum lacrimale, which is the beginning of the lacrimal canaliculus.

Lacrimal apparatus

The lacrimal apparatus, apparatus lacrimalis, includes the lacrimal gland with its excretory canaliculi and lacrimal ducts. The lacrimal gland, glandula lacrimalis, a complex alveolar-tubular gland with a lobular structure, lies in the fossa of the same name in the lateral corner of the upper wall of the orbit. The tendon of the levator palpebrae superioris muscle divides the gland into a large upper orbital part, pars orbitalis, and a smaller lower eyelid part, pars palpebralis, lying near the upper fornix of the conjunctiva. Under the fornix of the conjunctiva, small accessory lacrimal glands are sometimes found. The excretory canaliculi of the lacrimal gland, ductuli excretorii, up to 15 in number, open into the conjunctival sac in the lateral part of the upper fornix of the conjunctiva. The tear washes the eyeball, along the capillary fissure near the edges of the eyelids along the lacrimal stream, rivus lacrimalis, flows into the area of ​​the medial corner of the eye, into the lacrimal lake. In this place, short (about 1 cm) and narrow (0.5 mm) curved upper and lower lacrimal canaliculi, canaliculi lacrimales, begin, opening into the lacrimal sac, saccus lacrimalis, lying in the fossa of the same name in the inferomedial corner of the eye. It passes into the nasolacrimal sac. duct (up to 4 mm), ductus nasolacrimalis, opening into the lower nasal passage. The lacrimal part of the orbicularis oculi muscle is fused to the anterior wall of the lacrimal sac, which expands the lacrimal sac, which facilitates the absorption of tear fluid into it through the lacrimal canaliculi.

Refractive media of the eyeball. Cornea, lens, vitreous body, chambers of the eyeball, their functions. Formation and outflow of aqueous humor from the chambers of the eyeball.

Cameras of the eyeball.

The anterior chamber of the eyeball, camera anterior bulbi, containing aqueous humor, humor aquosus, is located between the cornea and the anterior surface of the iris. Through the opening of the pupil, the anterior chamber communicates with the posterior chamber of the eyeball, camera posterior bulbi. The latter is located between the lens and the posterior surface of the iris and is also filled with aqueous humor.

Formation and outflow of aqueous humor.

The anterior part of the ciliary body forms about 70 radially oriented folds, thickened at the ends, each up to 3 mm long - ciliary processes, processus ciliares, consisting of blood vessels and making up the ciliary crown, corona ciliaris. They produce aqueous humor, humor aquosus. Aqueous humor enters the spaces of the zonule, spatia zonularia, which have the appearance of a circular fissure (Petite canal) lying along the periphery of the lens. From there, aqueous humor flows through the pupil into the anterior chamber of the eyeball. It is circumferentially limited by the pectineal ligament, between the fiber bundles of which there are gaps - the spaces of the iridocorneal angle, spatia anguli iridocorneales (fountain spaces). Through them, aqueous humor from the anterior chamber flows into the venous sinus of the sclera, and from it enters the anterior ciliary veins.

Lens

The lens, lens, has an anterior and posterior surface, facies anterior et posterior lentis, anterior and posterior pole, polus anterior et posterior. The conventional line connecting the poles is called the axis of the lens, axis lentis. The peripheral edge of the lens is called the equator. The substance of the lens, substantia lentis, is colorless, transparent and dense. The inner part is the nucleus of the lens, nucleus lentis, denser than the peripheral part - the cortex of the lens, cortex lentis. On the outside, the lens is covered with a thin transparent elastic capsule, capsula lentis, which is attached to the ciliary body with the help of a ciliary band, zonula ciliaris (ligament of Zinn).

Organs of smell and taste.

Olfactory organ.

In humans, the organ of smell, organum olfactorium, is located in the upper part of the nasal cavity. The olfactory region of the nasal mucosa, regio olfactoria tunicae mucosae nasi, has neurosensory cells, epithelial cells, cellulae (epitheliocyti) neurosensoriae olfactoriae. Underneath them lie supporting cells, cellulae sustentaculares. The mucous membrane contains olfactory (Bowman's) glands, glandulae olfactoriae, the secretion of which moisturizes the surface of the receptor layer. The peripheral processes of the olfactory cells bear olfactory hairs (cilia), and the central ones form 15-20 olfactory nerves, which, through the openings of the cribriform plate of the same bone, penetrate into the cranial cavity, then into the olfactory bulb, where the axons of the olfactory neurosensory cells come into contact with the mitral cells . The processes of the mitral cells in the thickness of the olfactory tract are sent to the olfactory triangle, and then, as part of the olfactory stripes (intermediate and medial), enter the anterior perforated substance, the subcallosal area, area subcallosa, and the diagonal strip (Broca's strip), bandaletta (stria) diagonalis ( Broca). As part of the lateral stripe, the processes of mitral cells follow into the parahippocampal gyrus and into the uncus, which contains the cortical center of smell.

Organ of taste

Organ of taste, organum gustus. Taste buds, calliculi gustatorii, numbering about 2000, are located mainly in the mucous membrane of the tongue, as well as the palate, pharynx, and epiglottis. The largest number of them are located in the grooved papillae, papillae vallatae, and leaf-shaped papillae, papillae foliatae. Each bud is made up of taste and supporting cells. At the top of the bud there is a taste opening (pore), porus gustatorius. On the surface of taste cells are the endings of nerve fibers that perceive taste sensitivity. In the area of ​​the anterior 2/3 of the tongue, this sense of taste is perceived by the fibers of the tympanic chord of the facial nerve, in the posterior third of the tongue and in the area of ​​the circumvallate papillae) by the endings of the glossopharyngeal nerve. This nerve also innervates the mucous membrane of the soft palate and palatine arches. From sparsely located taste buds in the mucous membrane of the epiglottis and the inner surface of the arytenoid cartilages, taste impulses arrive through the superior laryngeal nerve, a branch of the vagus nerve. The central processes of the neurons that carry out taste innervation in the oral cavity are sent as part of the corresponding cranial nerves (VII, IX, X) to their common sensitive nucleus, nucleus solitarius. The axons of the cells of this nucleus are sent to the thalamus, where the impulse is transmitted to the following neurons, the central processes of which end in the cerebral cortex, the uncus of the parahippocampal gyrus. The cortical end of the taste analyzer is located in this gyrus.

Skin structure.

Rhomboid brain (-pons, medulla oblongata). Between the rhombencephalon and the midbrain is the isthmus of the rhombencephalon.

The brain is located in the cranial cavity. It has a convex upper lateral surface and a lower surface and a flattened one - the base of the brain.

The mass of the adult human brain ranges from 1100 to 2000 grams; from 20 to 60 years, mass m and volume V remain maximum and constant, after 60 years they decrease slightly. Neither absolute nor relative brain mass is an indicator of the degree of mental development. The brain weight of Turgenev was 2012 g, Byron - 2238 g, Cuvier - 1830 g, Schiller - 1871 g, Mendeleev - 1579 g, Pavlov - 1653 g. The brain consists of neuron bodies, nerve tracts and blood vessels. The brain consists of 3 parts: the cerebrum and the brain stem.

The cerebral hemispheres reach their maximum development in humans, later than other parts.

The cerebrum consists of the right and left, which are connected to one another by a thick commissure (commissure) - the corpus callosum. The right and left hemispheres are divided by the longitudinal fissure. Under the commissure there is a vault, which consists of two curved fibrous strands, 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 corpus callosum and the fornix is ​​a thin vertical plate of brain tissue - a transparent septum.

The hemispheres have superior lateral, medial and inferior surfaces. The superior lateral one is convex, the medial one is flat, facing the same surface of the other hemisphere, and the lower one is irregular in shape. On the three surfaces there are deep and shallow grooves, and convolutions between them. Fissures are depressions between the gyri. Gyri are elevations of the medulla.

The surfaces of the cerebral hemispheres are separated from each other by edges - superior, inferolateral and inferovertical. In the space between the two hemispheres, the falx cerebri enters - a large falciform process, which is a thin plate of the hard shell, which penetrates the longitudinal fissure of the cerebrum, without reaching the corpus callosum, and separates the right and left hemispheres from each other. The most prominent areas of the hemispheres are called poles: frontal, occipital and temporal. The surface relief of the cerebral hemispheres is very complex and is associated with the presence of more or less deep grooves in the cerebrum and roller-like elevations located between them - gyri. The depth, length of some grooves and convolutions, their shape and direction are very variable.

Each hemisphere is divided into lobes - frontal, parietal, occipital, insular. The central sulcus (Roland's sulcus) separates from the parietal, the lateral sulcus (Sylvian sulcus) separates the temporal from the frontal and parietal, the parieto-occipital separates the parietal and occipital lobes. The lateral sulcus is formed by the 4th month of intrauterine development, the parieto-occipital and central sulcus by the 6th month. In the prenatal period, gyrification occurs - the formation of convolutions. These three grooves appear first and are very deep. Soon a pair of parallel grooves are added to the central groove: one runs in front of the central one and is accordingly called the precentral, which splits into two - upper and lower. The other sulcus is located behind the central one and is called the postcentral sulcus.

The postcentral sulcus 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. On the superolateral surface of the hemisphere, below, the postcentral gyrus also passes into the precentral gyrus, covering the central sulcus from below. 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. Below this groove lies the inferior parietal lobule, within which two gyri are distinguished: supramarginal and angular. 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, overhanging the insula, form the frontoparietal operculum of the insula.

Finite brain (big brain) consists of the right and left hemispheres and the fibers connecting them, forming the corpus callosum and other commissures. Located under the corpus callosum vault in the form of two curved strands connected by adhesions. The anterior part of the arch, directed downwards, forms pillars. The rear part, diverging to the sides, is called arch legs. Anterior to the trunks of the arch there is a transverse bundle of fibers - anterior (white) commissure.

Anterior to the arch in the sagittal plane is located transparent partition, consisting of two parallel plates. Anteriorly and superiorly, these plates connect to the anterior part of the corpus callosum. Between the plates there is a narrow slit-like cavity containing a small amount of liquid. Each plate forms the medial wall of the anterior horn of the lateral ventricle.

Each cerebral hemisphere is formed by gray and white matter. The peripheral part of the hemisphere, covered with grooves and convolutions, forms cloak, covered with a thin plate of gray matter - cerebral cortex. The surface area of ​​the bark is about 220,000 mm2. Under the cerebral cortex is white matter in the depths of which there are large accumulations of gray matter - subcortical nuclei -basal ganglia . The cavities of the cerebral hemispheres are lateral ventricles.

Each hemisphere has three surfaces - superolateral(convex), medial(flat) facing the neighboring hemisphere, and lower, having a complex relief corresponding to the unevenness of the internal base of the skull. Numerous depressions are visible on the surfaces of the hemispheres - furrows and elevations between the furrows - convolutions

Each hemisphere has five beats : frontal, parietal, occipital, temporal and insular (island).

The furrows and convolutions of the cerebral hemispheres.

The lobes of the hemispheres are separated from each other by deep grooves.

Central sulcus(Rolandova) separates the frontal lobe from the parietal lobe;

Lateral sulcus(Silvieva) - temporal from the frontal and parietal;

Parieto-occipital sulcus separates the parietal and occipital lobes.

In the depths of the lateral sulcus is located insular lobe. Smaller grooves divide the lobes into convolutions.

Superolateral surface of the cerebral hemisphere.

In the frontal lobe in front and parallel to the central sulcus runs precentral sulcus, which separates precentral gyrus. From the precentral sulcus, two sulci extend more or less horizontally forward, dividing upper, middle And inferior frontal gyri. In the parietal lobe postcentral sulcus separates the gyrus of the same name. Horizontal intraparietal sulcus divides top And inferior parietal lobules, The occipital lobe has several convolutions and grooves, of which the most constant is transverse occipital groove. The temporal lobe has two longitudinal grooves - upper And inferior temporal separates three temporal gyri: upper, middle And bottom. The insular lobe in the depth of the lateral sulcus is separated by a deep circular groove of the insula from neighboring parts of the hemisphere,

Medial surface of the cerebral hemisphere.

All of its lobes take part in the formation of the medial surface of the cerebral hemisphere, except the temporal and insular. Long arched sulcus of the corpus callosum separates him from cingulate gyrus. Passes over the cingulate gyrus cingulate groove, which begins anteriorly and inferiorly from the beak of the corpus callosum, rises upward, turns backward along the groove of the corpus callosum. Posteriorly and inferiorly, the cingulate gyrus becomes parahippocampal gyrus, which goes down and ends in front crochet, superiorly the parahippocampal gyrus is bounded by the hippocampal sulcus. The cingulate gyrus, its isthmus and parahippocampal gyrus are combined under the name vaulted gyrus. Located deep in the hippocampal sulcus dentate gyrus. Above on the medial surface of the occipital lobe is visible parieto-occipital sulcus, separating the parietal lobe from the occipital lobe. From the posterior pole of the hemisphere to the isthmus of the vaulted gyrus passes calcarine groove. Between the parieto-occipital sulcus in front and the calcarine sulcus below is located wedge, facing at an acute angle anteriorly.

Inferior surface of the cerebral hemisphere

It has the most difficult terrain. In front is the lower surface of the frontal lobe, behind it is the temporal (anterior) pole and the lower surface of the temporal and occipital lobes, between which there is no clear boundary. On the lower surface of the frontal lobe runs parallel to the longitudinal fissure olfactory groove, to which it is adjacent below olfactory bulb And olfactory tract, continuing posteriorly in olfactory triangle. Between the longitudinal fissure and the olfactory groove is located straight gyrus. Lateral to the olfactory sulcus lie orbital gyri. On the inferior surface of the temporal lobe collateral groove separates medial occipitotemporal gyrus from parahippocampal. Occipitotemporal sulcus separates lateral occipitotemporal gyrus from the medial gyrus of the same name.

On the medial and lower surfaces there are a number of formations related to limbic system. These are the olfactory bulb, olfactory tract, olfactory triangle, anterior perforated substance, located on the lower surface of the frontal lobe and also related to the peripheral part of the olfactory brain, cingulate, parahippocampal (together with the hook) and dentate gyrus.