Anatomy of human brain. Middle part of the brain. Cerebrovascular disorders

The human brain is a multi-level system, which is the highest level of vegetative control and ensures the regulation of life support processes and the functions of all internal organs.

The brain consists of (Fig. 9):
two hemispheres connected to each other by the corpus callosum - corpus collosum;
diencephalon(visual tubercles and subtubercular region);
midbrain (plates of the roof of the quadrigeminal and peduncles of the greater brain);
hindbrain (pons, cerebellum and half of the hindbrain - the pons, part of the brainstem system);
medulla oblongata.

Rice. 9. Structure of the human brain

The brain has 12 pairs of cranial nerves that provide various functions(vision, hearing, taste, smell, control of facial muscles, etc.) (Fig. 10):
- I pair - olfactory nerve;
- II pair - the optic nerve, forming an incomplete crossover called chiasma opticum;
- III pair - oculomotor nerve;
- IV pair - trochlear nerve;
- V pair - trigeminal nerve;
- VI pair - abducens nerve;
- VII pair - facial nerve;
- VIII pair - vestibulocochlear (auditory) nerve;
- IX pair - glossopharyngeal nerve;
- X pair - vagus nerve;
- XI pair - accessory nerve;
- XII pair - hypoglossal nerve.


Fig. 10. Cranial nerves at the base of the brain.

The structure of the cerebral hemispheres
The cerebral cortex (cortex hemispheria cerebri), pallium, or mantle, a layer of gray matter (1-5 mm) covering the cerebral hemispheres. This part of the brain, which developed in the later stages of evolution, plays an extremely important role in the implementation of higher nervous activity and is involved in the regulation and coordination of all body functions. In humans, the cortex makes up approximately 44% of the volume of the entire hemisphere, its surface is on average 1468-1670 cm2.
In humans, due to the uneven growth of individual structures of the gray matter, the surface of the cortex becomes folded, covered with grooves and convolutions. Furrows and convolutions increase the surface of the cortex without increasing the volume of the skull. So, a person has approx. 2/3 of the surface of the entire cortex is located deep in the grooves. The structure of the cortex is characterized by orderliness with a horizontal-vertical distribution of neurons in layers and columns. The structural and functional unit of the cortex is a module (union, block), consists of special, pyramidal, stellate and spindle-shaped cells, as well as fibers and vessels and has a diameter of about 100-150 microns. Many different influences (exciting and inhibitory) converge on the modules. As a result of their combination (integration) through the spatiotemporal summation of local electrical potentials, synchronous impulse volleys are formed on the cell membrane. Such elementary modules are included in larger associations of neurons (columns) with a diameter of up to 1 mm.
Differences in the structure of individual sections of the cortex (location density, size of neurons, their organization into layers and columns) determine the architecture of the cortex, or its cytoarchitectonics. The cortex has close connections with underlying brain structures, which direct their nerve fibers and are themselves under the control of certain cortical zones, receiving regulatory influences from them along nerve pathways. The cortex is divided into projection (primary and secondary sensory), associative (tertiary multisensory) and integrative-triggering (motor, etc.) fields, which is associated with the complex nature of information processing and the formation of a program of goal-directed behavior (Fig. 11, 12).

1. Prefrontal cortex.
2. Tactile analysis.
3. Auditory cortex (left ear).
4. Spatial visual analysis.
5. Visual cortex (left visual fields).
6. Visual cortex (right visual fields).
7. General center of interpretation (speech and mathematical operations).
8. Auditory areas of the cortex ( right ear).
9. Writing (for right-handers).
10. Speech center.

Rice. 11. Zones of the cerebral cortex.

1. Associative motor area.
2. Primary motor area.
3. Primary somatosensory area.
4. Parietal lobe of the cerebral hemispheres.
5. Associative somatosensory area.
6. Associative visual area.
7. Occipital lobe of the cerebral hemispheres.
8. Primary visual area. 9. Associative auditory zone.
10. Primary auditory zone.
11. Temporal lobe of the cerebral hemispheres.
12. Olfactory cortex.
13. Gustatory bark.
14. Prefrontal association zone.
15. Frontal lobe of the cerebral hemispheres.

The hemispheres are separated by a longitudinal fissure, in the depth of which lies the plate white matter, consisting of fibers connecting the two hemispheres - 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.

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 (Fig. 12).

Anatomy of the medulla oblongata

The part of the brain closest to and associated with spinal cord is called the medulla oblongata (Fig. 13). The border between the spinal cord and the medulla oblongata is the place where the roots of the first cervical nerves emerge. spinal nerves.

At the top it passes into the medullary pons, its lateral sections continue into the lower cerebellar peduncles. On its front (ventral) surface two longitudinal elevations are visible - pyramids and olives lying outward from them.

In the medulla oblongata there are nuclei of the IX-XII pairs of cranial (cranial) nerves, which emerge on its lower surface behind the olive and between the olive and the pyramid. The reticular (reticular) formation of the medulla oblongata consists of an interweaving of nerve fibers and nerve cells lying between them, forming the nuclei of the reticular formation.
The white matter is formed by long systems of fibers passing here from the spinal cord or heading into the spinal cord, and short ones connecting the nuclei of the brain stem.

Anatomy of the hindbrain
The hindbrain includes the medullary pons and cerebellum.
The pons borders the medulla oblongata from below, passes into the cerebral peduncles from above, its lateral sections form the middle cerebellar peduncles

In the anterior (ventral) part of the pons there are clusters of gray matter - the own nuclei of the pons; in the posterior (dorsal) part there are the nuclei of the V - VIII pairs of cranial nerves. These nerves emerge from the base of the brain lateral to and behind the pons at the border with the cerebellum and medulla oblongata.
Cerebellum
The cerebellum is located dorsal to the pons and medulla oblongata (Fig. 15). It has two hemispheres and a middle part - the worm. The surface of the cerebellum is covered with a layer of gray matter (cerebellar cortex) and forms narrow convolutions separated by grooves. With their help, the surface of the cerebellum is divided into lobules. The central part of the cerebellum consists of white matter, which contains accumulations of gray matter - the cerebellar nuclei. The largest of them is the dentate nucleus. The cerebellum is connected to the brain stem by three pairs of peduncles: the upper ones connect it to the midbrain, the middle ones to the pons, and the lower ones to the medulla oblongata. They carry bundles of fibers connecting the cerebellum with various parts of the brain and spinal cord.

During development, the isthmus of the rhombencephalon forms the boundary between the hindbrain and midbrain. From it develop the superior cerebellar peduncles, the superior (anterior) medullary velum located between them, and the triangles of the loop, which lie outward from the superior cerebellar peduncles.

Anatomy of the midbrain
Midbrain, is the smallest and most simply structured part of the brain in humans; it has two main parts: the roof, where the subcortical centers of hearing and vision are located, and the cerebral peduncles, where the pathways predominantly pass.
1. Dorsal part, roof of the midbrain, tectum mesencephali.
It is hidden under the posterior end of the corpus callosum and is divided by two criss-crossing grooves - longitudinal and transverse - into four hillocks, arranged in pairs.
The upper two hillocks, colliculi superiores, are subcortical centers of vision, the two lower ones, colliculi inferiores, are subcortical centers of hearing. The pineal body (Epiphysis) lies in a flat groove between the superior tubercles.
2. The ventral part, the cerebral peduncles, pedunculi cerebri, contains all the pathways to the forebrain.
The cerebral peduncles look like two thick semi-cylindrical white cords that diverge from the edge of the pons at an angle and plunge into the thickness of the cerebral hemispheres.
3. The midbrain cavity, which is a remnant of the primary cavity of the midbrain bladder, has the appearance of a narrow canal and is called the cerebral aqueduct, aqueductus cerebri. It is a narrow, ependymal-lined canal 1.5-2.0 cm long, connecting the IV ventricle with the III. Dorsally, the aqueduct is limited by the roof of the midbrain, ventrally by the tegmentum of the cerebral peduncles.
According to the development of the midbrain under the influence visual receptor it contains various nuclei related to the innervation of the eye.

The brain (cerebrum) with its surrounding membranes is located in the cavity of the brain skull. The convex surface of the brain corresponds in shape to the inner concave surface of the cranial vault.

The lower surface - the base of the brain - has a complex topography corresponding to the cranial fossae of the inner base of the brain.

The mass of the adult human brain ranges from 1100 to 2000. From 20 to 60 years, the mass and volume remain constant, and after 60 years they decrease slightly. When examining the brain, the cerebral hemispheres, cerebellum and brain stem are distinguished.

The hemispheres of the cerebrum are separated from each other by a deep longitudinal fissure of the cerebrum, reaching the corpus callosum. In the posterior sections, the longitudinal fissure flows into the transverse fissure of the cerebrum, which separates the hemispheres from the cerebellum. There are deep and shallow grooves on all surfaces of the cerebral hemispheres. Deep grooves divide each of the hemispheres into lobes of the cerebrum. Small grooves separate the convolutions of the cerebrum from each other. The lower surface of the brain is formed by the ventral surfaces of the cerebral hemispheres, the cerebellum and the ventral sections of the brain stem (Fig. 61).

Rice. 61. Brain, sagittal section:

1 - corpus callosum; 2 - vault; 3 - thalamus; 4 - roof of the midbrain; 5 - midbrain aqueduct; 6 - cerebral peduncle; 7 - IV ventricle; 8 - bridge; 9 - cerebellum; 10 - medulla oblongata; 11 - mastoid body; 12 - pituitary gland; 13 - visual chiasm. Cerebral hemisphere: a - parietal lobe; b - occipital lobe; c - temporal lobe; g - frontal lobe

At the base of the brain, in the anterior sections, olfactory bulbs are found, which look like small thickenings, from which a large nerve cord stretches back - the olfactory tract,

passing into the olfactory triangle. Adjacent to the latter is the anterior perforated substance, formed by arteries penetrating deep into the brain. More medially is the optic chiasm, formed by the fibers of the optic nerve, which, partially crossing, emerge from the chiasm as part of the optic tracts. A gray tubercle is adjacent to the posterior surface of the optic chiasm, lower sections which is elongated in the shape of a funnel. At the lower end of the funnel there is a rounded formation - the pituitary gland. Adjacent to the gray tubercle are two white spherical elevations - the mastoid bodies.

Behind the optic tracts, two longitudinal white ridges are visible - the cerebral peduncles, and a depression - the interpeduncular fossa, the bottom of which is formed by the posterior perforated substance. Next is a wide transverse ridge - the bridge, the lateral sections of which continue into the cerebellum, forming its middle cerebellar peduncles.

Caudal to the pons, the sections of the medulla oblongata are represented by medially located pyramids, separated from each other by the anterior median fissure, and laterally by olives.

The extensive medial surface of the cerebral hemispheres hangs over the much smaller cerebellum and brain stem. On the medial surface of the hemispheres, as on other surfaces, grooves are visible that separate the gyri from each other.

Areas of the frontal, parietal and occipital lobes are separated from the corpus callosum by the groove of the same name.

The middle part of the corpus callosum is called the trunk, the anterior sections of which, bending downwards, form the knee of the corpus callosum. Below, the corpus callosum becomes thinner and passes into the beak of the corpus callosum, the posterior sections of the corpus callosum noticeably thicken and end in the form of a ridge. In the middle part of the corpus callosum, a thin white plate called the body of the fornix separates. Separating from the corpus callosum and forming an arched bend forward and downward, the body of the vault passes into the column of the vault, which ends with the mastoid body, and at the back it passes into the crura of the vault.

Between the columns of the fornix, a bundle of nerve fibers runs transversely, visible on the cut in the form of a white oval - the anterior commissure of the brain.

The columns of the fornix surround a thin plate of medulla - the transparent septum.

All of the listed brain formations belong to the telencephalon.

The structures located below belong to the brain stem (intermediate, middle, posterior parts of the brain and medulla oblongata) (Fig. 62).

Rice. 62. Brain, base:

1 - frontal lobe of the cerebral hemisphere; 2 - temporal lobe of the cerebral hemisphere; 3 - bridge; 4 - pyramid of the medulla oblongata; 5 - cerebellum; 6 - olfactory bulb; 7 - olfactory tract; 8 - optic nerve; 9 - visual chiasm; 10 - pituitary gland; 11 - visual tract; 12 - mastoid body; 13 - oculomotor nerve; 14 - trochlear nerve; 15 - trigeminal nerve; 16 - abducens nerve; 17 - facial nerve; 18 - vestibulocochlear nerve; 19 - glossopharyngeal nerve; 20 - vagus nerve; 21 - accessory nerve; 22 - hypoglossal nerve

The most anterior parts of the brain stem are formed by the optic sulci, which are located inferior to the body of the fornix and the corpus callosum and behind the trunks of the fornix.

On a midline section of the brain, only the medial surface of the posterior thalamus is visible, which limits the slit-like, vertically located cavity of the third ventricle.

Between the anterior end of the visual thalamus and the anterior leg of the fornix there is an interventricular foramen that connects the lateral ventricles of the cerebral hemispheres with the cavity of the third ventricle; the optic chiasm, gray tubercle, infundibulum, pituitary gland and mastoid bodies take part in the formation of the bottom of the latter.

In the back upper section On the visual hillocks there is a pineal body, the anterior-inferior parts of which are connected by a thin transversely running cord - an elastic commissure. Below it is the beginning of the midbrain aqueduct.

The visual tuberosities and the formations located next to them belong to the diencephalon. To the back surface of the optic

The tuberosities are adjacent to formations related to the midbrain. Caudal to the pineal gland is the roof of the midbrain, consisting of the superior and inferior colliculi (in a midline section). Ventral to the plate is the cerebral peduncle, separated from the plate by the cerebral aqueduct. The cavities of the third and fourth ventricles communicate through the midbrain aqueduct. Even further away are the pons and cerebellum, which belong to the hindbrain, and the medulla oblongata. The cavity of these parts of the brain makes up the IV ventricle. The floor of the ventricle is formed by the dorsal surfaces of the pons and medulla oblongata, constituting the rhomboid fossa.

Medulla

The medulla oblongata (medulla oblongata) is a direct continuation of the spinal cord and has the appearance of a bulb, the upper extended end of which borders the pons. On the anterior surface, the anterior median fissure runs along the midline. On its sides there are two longitudinal strands - pyramids, lateral to them - olives; on the posterior surface the posterior cords are visible - a continuation of the cords of the spinal cord. Toward the top, the posterior cords diverge to the sides and go to the cerebellum, forming the lower cerebellar peduncles or rope bodies bordering the rhomboid fossa. The lower legs contain the Flexig bundle and part of the fibers arising in the nuclei of the posterior funiculi. The ascending fibers of the dorsal roots of the spinal cord are located in the posterior cords - the gentle fascicle of Gaulle and the wedge-shaped fascicle of Burdach. On the lateral surfaces of the medulla oblongata, behind the olive, the IX, X and XI pairs of cranial nerves emerge. The medulla oblongata contains Bottom part rhomboid fossa.

The medulla oblongata contains the dentate olive nucleus, which is connected to the cerebellar nucleus of the same name; reticular formation, consisting of nerve fibers that are connected to the reticular formation of the spinal cord; nuclei of cephalic nerves IX-XII; centers of respiration, blood circulation, digestion.

The white matter of the medulla oblongata contains long and short fibers. The long fibers include the descending pyramidal tracts that transiently pass into the anterior cords of the spinal cord.

In addition, from the nuclei of the posterior funiculi, the second neurons of the ascending sensory pathways begin, going from the medulla oblongata to the visual thalamus. The fibers of this bundle form a medial loop, which forms a decussation in the medulla oblongata. To short

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

Pons

The pons, or pons, is a thick white shaft that lies between the medulla oblongata and midbrain. The middle cerebellar peduncles approach the pons. On the cross-section of the bridge, you can see that it consists of dorsal and basal parts, the boundary between them is a layer of transverse fibers that form a trapezoidal body, in the lateral part of which a large core, the superior olive, lies above it. The trapezoid body and superior olive belong to the auditory pathway, ventral to these tracts longitudinal fibers are visible, which belong to pyramidal paths and are connected with their own brain nuclei. This entire system of pathways connects the cerebral cortex with the cerebellar cortex. In the dorsal part there is a reticular formation, and on top of the reticular formation there is the bottom of the rhomboid fossa, with the nuclei of the cranial nerves of the V-VIII pairs lying in it.

Cerebellum

The cerebellum (cerebellum) is a derivative of the hindbrain, occupies the posterior cranial fossa, located under the occipital lobes of the cerebral hemispheres (Fig. 63). It distinguishes between hemispheres that are connected by a worm. The surface of the cerebellum is covered with a layer of gray matter that makes up the cerebellar cortex, and forms narrow convolutions separated from each other by grooves. The horizontal fissure separates the superior surface of the cerebellar hemispheres from the inferior. With the help of grooves, the surface of the cerebellum is divided into lobules.

In the thickness of the cerebellum there are paired nuclei of gray matter, located in each half of the cerebellum (Fig. 64). The most medial nucleus is

Rice. 63. Cerebellum (top view):

1 - cerebellar vermis; 2 - gyri of the cerebellum; 3 - right hemisphere; 4 - left hemisphere; 5 - cerebellar cortex

the tent core (connected with the vestibular apparatus), the spherical and cortical nuclei are located laterally (they regulate the work of the trunk muscles). In the center of the hemispheres is the dentate nucleus (regulates the functioning of the muscles of the limbs).

The white matter of the cerebellum in a section looks like small leaves of a plant; towards the center, small leaves unite into larger ones. The white matter of the cerebellum resembles a tree.

Rice. 64. Cerebellar nuclei (cross section):

1 - fourth ventricle; 2 - superior cerebellar peduncles; 3 - tent core; 4 - spherical nucleus; 5 - corky core; 6 - dentate core; 7 - cerebellar cortex

Some nerve fibers of the white matter of the cerebellum connect the gyri and lobules, others go from the cortex to the cerebellar nuclei, and others, which are part of three pairs of cerebellar peduncles, connect the cerebellum with other parts of the brain. The inferior cerebellar peduncles connect to the medulla oblongata. Fibers from the nuclei passing here vestibular apparatus end in the tent core, receiving impulses from the vestibular apparatus and proprioceptive field. The middle cerebellar peduncles connect to the pons and contain nerve fibers passing from the pons nuclei to the cerebellar cortex. These pathways also connect the cerebral cortex with the cerebellar cortex.

The superior cerebellar peduncles connect to the midbrain and consist of nerve fibers running in two directions: to the cerebellum and from the dentate nucleus of the cerebellum to the roof of the quadrigeminal, and after decussation they pass through the red nucleus and the optic thalamus. Along the first path, the cerebellum sends impulses to the extrapyramidal system, through which it influences the spinal cord. The cerebellum is directly related

to coordination of movements and mechanisms for overcoming the basic properties of body mass - gravity and inertia. It is one of the higher centers of the autonomic nervous system.

Midbrain

The midbrain (mesencephalon) is formed by the cerebral legs, the roof of the brain and the cavity - the Sylvian aqueduct (Fig. 65).

The cerebral peduncles look like two thick semi-cylindrical white cords. They go from the upper edge of the bridge upward, where they diverge and plunge into the thickness of the cerebral hemispheres. At the entrance to the hemisphere, the optic tracts spread through the legs (Fig. 66).

Rice. 66. Cross section of the midbrain: 1 - nucleus of the superior colliculus; 2 - midbrain aqueduct; 3 - central gray matter; 4 - medial loop; 5 - black substance; 6 - base of the cerebral peduncle; 7 - red core; 8 - oculomotor nerve

Rice. 65. Brain stem (front view): 1 - upper part of the thalamus; 2 - cavity of the third ventricle; 3 - pineal body; 4 - upper hills of the quadrigeminal; 5 - lower hills of the quadrigeminal; 6 - superior cerebellar peduncles; 7 - cavity of the rhomboid fossa; 8 - lateral bundle (Burdakha); 9 - medial bundle (Gaull)

The roof of the brain is hidden under the cerebral hemispheres above the posterior end of the corpus callosum and is represented by the quadrigeminal plate.

The cavity of the midbrain - the aqueduct of Sylvius - is a narrow canal 1.5-2.0 cm long, connecting the III and IV ventricles. Dorsally, the aqueduct is limited by the roof of the midbrain, and ventrally by the tegmentum of the cerebral peduncles. It is surrounded by central gray matter (provides

autonomic functions) and contains the nuclei of the oculomotor and trochlear nerves.

The quadrigeminal tubercles consist of superior and inferior colliculi. The superior colliculi contain the subcortical centers of vision, and the inferior colliculi contain the centers of hearing. In the midbrain there is the substantia nigra, which belongs to the extrapyramidal system (subcortical motor center). The cell bodies of this substance contain pigment.

The red nucleus has an elongated shape, extends along the tegmentum of the cerebral peduncle from the subthalamic region of the diencephalon to the inferior colliculus, where the descending tract begins, connecting the red nucleus with the anterior horns of the spinal cord. Fibers come to it from the cerebellum. Thanks to these connections, the cerebellum and the extrapyramidal system, through the red nucleus, influence all skeletal muscles in the process of automatic movements (walking, running, swimming, etc.).

III pair - oculomotor nerve, innervates the muscles of the eye.

IV pair - trochlear nerve - motor, innervates the superior oblique muscle of the eyeball.

The reticular formation is located in the midbrain.

Diencephalon

The diencephalon (dien-cephalon) consists of the thalamus (visual thalamus), hypothalamus (sub-tuberculous region), epithalamus and metathalamus (Fig. 67).

Thalamus - ovoid in shape; The gray matter in the thalamus has the form of nuclei (about 40). Among them are the anterior nucleus, which is associated with the olfactory analyzer, and the posterior nucleus, associated with the visual analyzer. All sensory conductors pass through the lateral nucleus on their way to the cortex. The thalamus is the center of pain sensitivity.

Hypothalamus (hypothalamus) - it includes the gray tubercle - one of the vegetative centers of thermoregulation and metabolism, the pituitary gland,

Rice. 67. Brain stem (sagittal section): 1 - corpus callosum; 2 - vault; 3 - interthalamic fusion; 4 - thalamus; 5 - posterior commissure; 6 - pineal body; 7 - plate of the roof of the midbrain; 8 - midbrain aqueduct; 9 - mastoid body; 10 - cerebral peduncle; 11 - IV ventricle; 12 - bridge; 13 - medulla oblongata; 14 - cerebellum

optic chiasma (chiasm) of the second pair of cranial nerves, mammillary bodies as subcortical centers of smell. The hypothalamus contains nuclei that regulate autonomic and endocrine functions body.

The epithalamus has leashes and a pineal gland, attached by these leashes to the thalamus. The pineal body is an endocrine gland, one of whose functions is to synchronize the body’s biorhythms with the rhythms of the external environment.

Metathalamus (metathalamus) - the post-thalamic part, is represented by paired lateral and medial geniculate bodies. The lateral geniculate bodies, together with the superior colliculi of the midbrain, are the subcortical centers of vision, and the medial geniculate bodies are the subcortical centers of hearing.

Basal ganglia

In the thickness of the white matter of the cerebral hemispheres, in the region of their base, lateral and slightly downward from the lateral ventricles, there is gray matter, which forms clusters of various shapes, called gray nuclei (basal ganglia) or nodes of the base of the terminal brain (Fig. 68). The base of the brain nodes in each hemisphere include four nuclei: the caudate nucleus, the lenticular nucleus, the cerebral nucleus, and the amygdala. The caudate and lenticular nuclei are combined under the name striatum.

The caudate nucleus (nucleus caudatus) consists of Fig. 68. Brain (frontal section):

heads of the caudate nucleus,

1 - internal capsule; 2 - shell; 3 - fence;

4 - outer capsule; 5 - globus pallidus; 6 - lentil - forming a lateral shaped nucleus; 7 - cerebral cortex; 8 - thalamus; wall of the anterior horn bo-9 - caudate nucleus; 10 - white matter; 11 - cerebellar ventricle body leaf body

adjacent to the superolateral surface of the visual thalamus, and a tail descending into the temporal lobe, into the region of the lateral ventricle.

The lentiform nucleus (nucleus lentiformis) is located outside the caudate nucleus and has a lenticular shape. The lenticular nucleus is divided into three parts by small layers of white matter, the lateral nucleus is called the putamen, and the remaining nuclei are called the globus pallidus.

The claustrum is located lateral to the lenticular nucleus and is an elongated plate up to 2 mm thick.

The amygdala (corpus amygdaloideum) is located deep in the temporal lobe, in the region of the temporal pole, in front of the apex of the inferior horn.

These gray nuclei of the base of the telencephalon are separated from one another by layers of white matter - capsules, which are systems of brain pathways.

The layer of white matter located between the optic thalamus and the caudate nucleus is called the internal capsule, and the one located between the lenticular nucleus and the fence is called the external capsule.

Finite brain

The telencephalon consists of two hemispheres of the cerebrum, separated by a longitudinal fissure and connected

between themselves in the depths of this gap using a thick horizontal plate of the corpus callosum, anterior and posterior commissures, as well as a commissure of the fornix. Each hemisphere contains white matter (neuron processes) and gray matter (neuron cell bodies). Part of the gray matter is located in the thickness of the cerebral hemispheres closer to the base and is called the basal ganglia. Another part of the gray matter covers the white matter in the form of a cloak (cerebral cortex). The “cloak” appears to be crumpled or gathered into folds, due to which its surface has a complex pattern consisting of furrows alternating in different directions and ridges between them, called convolutions.

13 1211 10 ■ IV

Rice. 69. Cerebral hemisphere (left, superolateral surface):

I - frontal lobe; II - parietal lobe; III - occipital lobe; IV - temporal lobe; 1 - superior frontal gyrus; 2 - middle frontal gyrus; 3 - inferior frontal gyrus; 4 - precentral gyrus; 5 - central groove; 6 - postcentral gyrus; 7 - supramarginal gyrus; 8 - superior parietal lobule; 9 - angular gyrus; 10 - inferior temporal gyrus; 11 - middle temporal gyrus; 12 - superior temporal gyrus; 13 - lateral groove

The corpus callosum consists of nerve fibers running transversely from one hemisphere to the other. It is distinguished by a front end that curves downwards, or a knee, a middle part and a rear end - thickened, in the shape of a roller. The upper surface of the corpus callosum is covered with a thin layer of gray matter. The genu of the corpus callosum, bending downwards, becomes sharp and forms a beak, which turns into a thin plate. Under the corpus callosum there is a vault, which represents two arched white knives that form the columns of the vault in front, and the legs of the vault behind.

In each hemisphere, three surfaces are distinguished: dorsolateral, which repeats the relief of the cranial vault, medial, facing the same surface of the other hemisphere, and basal, which has a complex shape. The depression on the basal surface (Sylvian fossa) divides it into anterior and posterior sections.

The hemisphere has an anterior (frontal), posterior (occipital) and temporal end, corresponding to the protrusion of the basal surface.

Deep fissures divide each hemisphere into large areas called lobes - frontal, parietal, temporal, occipital, and a lobe hidden at the bottom of the Sylvian fissure (the so-called insula).

The dorsolateral surface is divided into lobes by three grooves - Sylvian, central (Rolandic) and top end parietal sulcus. The Sylvian fissure begins from the Sylvian fossa (basal surface) and passes to the lateral surface. Two small grooves extend from the Sylvian fissure in the anterior part and go to the frontal lobe. The central sulcus begins at the top of the hemisphere and runs forward and downward. This groove divides the hemisphere into the following lobes: frontal, parietal, temporal, occipital and insula.

The frontal lobe is divided by the precentral gyrus into one vertical and three horizontal gyri.

The vertical gyrus is located between the central and precentral sulci. The horizontal gyri of the frontal lobe are as follows: superior frontal, middle frontal and inferior frontal.

Parietal lobe - on it, parallel to the central sulcus, the postcentral sulcus is located. It is divided into three convolutions - one vertical and two horizontal. The postcentral gyrus is the center of touch, pain and temperature sensitivity. Close to the specified center in localization and function, the center of stereognosia (recognition of objects by touch) is located in the superior parietal lobule and is separated from the inferior parietal lobule by the intraparietal sulcus, perpendicular to the postcentral sulcus. Within

The inferior parietal lobule contains the supramarginal gyrus, into which the lateral sulcus (landmark of the gyrus) abuts. This is the center of praxia (synthesis of purposeful skills of a labor, sports nature, etc.). Below the supramarginal gyrus, the angular gyrus is visible - the reading center (visual analyzer of written speech). For right-handed people, the last two centers are located on the left.

The temporal lobe has five convolutions running parallel to the lateral sulcus and towards each other. Three gyri, separated by the superior and inferior temporal sulci, are visible on the superolateral surface, and two are visible on the inferior and medial surfaces of the hemispheres. In the posterior part of the superior temporal gyrus (on the left for right-handers) there is an auditory speech analyzer (sensory speech center). In the middle section of the superior temporal gyrus - on the surface facing the insula - the nucleus of the auditory analyzer is located. The most medial in the temporal lobe is the parahippocampal gyrus (next to it, in the thickness of the temporal lobe, the hippocampus lies). The anterior section of the gyrus is curved and is therefore called the hook. The centers of smell and taste are located here.

On the medial surface of the occipital lobe, a deep calcarine groove is clearly visible, above and below which are the cuneus and the lingual gyrus, respectively, which are the center of the visual analyzer.

The basal surface of the hemisphere, which lies in front of the Sylvian fossa, belongs to the frontal lobe. Here, parallel to the medial edge of the hemisphere, runs the optic sulcus, in which the optic tract lies. Between this groove and the medial edge of the hemisphere there is a straight gyrus, which is a continuation of the superior frontal gyrus. The posterior portion of the basal surface of the hemisphere represents the lower surface of the temporal and occipital lobes, which here do not have clear boundaries.

The medial surface of the hemisphere - on it, directly above the corpus callosum, there is a groove of the corpus callosum, which turns into a deep groove of the hippocampus. Above the groove of the corpus callosum there is a second arcuate groove - the cingulate groove, the direct continuation of which is the subparietal groove. On the medial surface of the occipital lobe there is a wedge bounded posteriorly by the calcarine groove. The cingulate sulcus and the sulcus of the corpus callosum limit the cingulate gyrus, the isthmus of which continues into the hippocampal gyrus. The anterior section of this gyrus forms a bend - a hook.

The surface of the hemisphere, or cloak (pallium), is formed by a uniform layer of gray matter 1.5-4.5 mm thick - the cerebral cortex.

The structure of the cerebral cortex (gray matter)

The nerve cells and fibers that form the cerebral cortex are located in six layers (Fig. 70):

1st layer - molecular, contains a few small cells and fibers located parallel to the surface;

2nd layer - outer granular, formed by densely located round cells - multipolar neurons, grouped in the form of very small pyramids;

The 3rd layer is the outer pyramidal layer, consisting of pyramidal cells, the sizes of which increase inward. They are arranged in columns;

4th layer - internal granular, formed by rounded stellate cells and a dense accumulation of myelin fibers;

5th layer - internal pyramidal, contains pyramidal cells, among which there are very large fibers lying radially and horizontally;

Layer 6 is multimorphic, characterized by strong variability in the density and distribution of both cells and fibers. The cells are arranged in columns.

Rice. 70. Structure of the cerebral cortex (diagram): I - molecular layer; II - outer granular layer; III - outer pyramidal layer; IV - internal granular layer; V - inner pyramidal layer; VI - multimorphic layer; VII - strip of molecular plate; VIII - strip of outer granular plate; IX - strip of internal granular plate; X - strip of the inner pyramidal plate

White matter of the cerebral hemispheres

The white matter, located under the cerebral cortex, above the corpus callosum forms a solid mass, which stands out in the form of a semi-oval in a horizontal section. Below, the white matter is interrupted by clusters of gray (basal ganglia) and is located between them in the form of layers or capsules surrounding them. The largest of them, the internal capsule, is a continuation of the base of the cerebral peduncles and consists of projection tracts, both ascending and descending.

The white matter consists of associative, commissural and projection fibers.

Association fibers connect various areas cortex of the same hemisphere. Short fibers pass at the bottom of the grooves and connect adjacent gyri, and long fibers connect the gyri of different lobes.

Commissural fibers connect the symmetrical parts of both hemispheres. The corpus callosum is the largest commissural system, connecting identical areas of the neocortex.

Projection fibers extend beyond the hemispheres; they provide bilateral communication between the cortex and the underlying parts of the central part of the nervous system, right up to the spinal cord.

Lateral ventricles

The lateral ventricle of the hemisphere consists of a middle part and horns extending from it.

The middle part in the form of a narrow horizontal slit is located at the level of the parietal lobe, above the optic thalamus, and contains the choroid plexus of the lateral ventricle.

The anterior horn, which has a triangular cross-section, is located in the frontal lobe. It is separated from the anterior horn of the other hemisphere by a transparent septum - a rudimentary wall of the brain bladder located between the corpus callosum and the column of the fornix.

The posterior horn, deepening into the occipital lobe, is small; on its inner wall there is a significant protrusion (bird spur), formed by the depression of a deep spur slot; the lower wall is also slightly elevated by the collateral fissure.

The inferior horn runs forward and downward through the temporal lobe. Its bottom is elevated by the collateral fissure; the medial wall is strongly pressed deep into the hippocampal fissure and forms Ammon's horn here.

The interventricular foramina, located between the middle part and the anterior horns, connect the cavities of the lateral ventricles with the cavity of the third ventricle. Through these openings the choroid plexuses of the third and both lateral ventricles pass into each other.

Third ventricle

The third ventricle (Ninus tertius) occupies a central position in the diencephalon. The ventricular cavity has the appearance of a sagittally located narrow slit, bounded by six walls: two lateral, upper, lower, anterior and posterior. The cerebral aqueduct connects the cavities of the third and fourth ventricles.

Fourth ventricle

The fourth ventricle (guartus) is formed by the pons, cerebellum and medulla oblongata. The cavity of these parts of the brain makes up the IV ventricle. The shape of the cavity of the IV ventricle resembles a tent, the bottom of which has the shape of a rhombus (diamond-shaped fossa) and is formed by the posterior surfaces of the medulla oblongata and the pons. With the help of the foramina of Luschka and Magendie, the cavity of the fourth ventricle is connected to the subarachnoid space of the brain.

Localization of functions in the cerebral cortex

The cerebral cortex is the most highly organized matter with which higher nervous activity and regulation of the functions of all organs. The results of research and observations led to the conclusion that the cerebral cortex contains centers that regulate the performance of various functions. Such research began in 1874 by the Kyiv anatomist V.A. Betz created special maps of the cerebral hemispheres. I.P. Pavlov considered the cerebral cortex as a continuous perceptive surface, as a collection of cortical ends of analyzers. “Various analyzers are closely interconnected, therefore, analysis and synthesis are carried out in the cerebral cortex, and the development of responses that regulate any type of human activity. All this allows us to talk about the dynamic localization of functions in the cerebral cortex” (I.P. Pavlov).

Let us consider the position of some cortical ends of various analyzers (nuclei) in relation to the convolutions and lobes of the cerebral hemisphere in humans in accordance with the cytoarchitectonic map (Fig. 71).

1. The core of the cortical analyzer of general (temperature, pain, tactile) and proprioceptive sensitivity is formed by nerve cells located in the cortex of the postcentral gyrus (fields 1, 2, 3) and the superior parietal lobule (field 7) (Fig. 72).

Rice. 71. Cytoarchitectonic map of the left hemisphere of the cerebrum, superolateral surface. Explanation in the text

2. The core of the motor analyzer is located mainly in the so-called motor area of ​​the cortex, which includes the precentral gyrus (fields 4 and 6) and the paracentral lobule on the medial surface of the hemisphere. In the fifth layer of the cortex of the precentral gyrus, gigantopyramidal neurons (Betz cells) lie (Fig. 73).

3. The analyzer core, which provides the functions of combined rotation of the head and eyes in the opposite direction, is located in the posterior parts of the middle frontal gyrus, in the so-called premotor zone (field 8).

4. The nucleus of the motor analyzer is located in the region of the inferior parietal lobule, in the supramarginal gyrus (area 40).

5. The nucleus of the skin analyzer is located in the cortex of the superior parietal lobule (field 7).

6. The nucleus of the auditory analyzer is located deep in the lateral sulcus, on the surface of the middle part of the superior temporal gyrus facing the insula.

7. The nucleus of the visual analyzer is located on the medial surface of the occipital lobe of the cerebral hemisphere, on both sides of the calcarine sulcus (fields 18, 19).

8. Core olfactory analyzer located on the lower surface of the temporal lobe of the cerebral hemisphere, in the area of ​​the hook and partly in the area of ​​the hippocampus (field 10).

9. The nucleus of the motor analyzer of written speech (an analyzer of voluntary movements associated with writing letters and other characters) is located in the posterior part of the middle frontal gyrus (field 40).

Rice. 72. Cortical center general sensitivity.

Projections of parts of the human body onto the area of ​​the cortical end of the general sensitivity analyzer located in the cortex of the postcentral gyrus of the cerebrum are shown.

Rice. 73. Motor area of ​​the cerebrum.

Projections of parts of the human body in the cortex of the precentral gyrus of the cerebrum are shown.

1 - superolateral surface of the hemisphere (postcentral gyrus); 2 - temporal lobe; 3 - lateral groove; 4 - lateral ventricle; 5 - longitudinal fissure of the brain

If field 40 is damaged, agraphia occurs - loss of the ability to make precise, subtle movements when writing letters, signs and words.

10. The core of the motor analyzer of speech articulation (speech motor analyzer) is located in the posterior parts of the inferior frontal gyrus (area 44, or Broca’s center); damage to this field is accompanied by a loss of the ability to compose meaningful sentences from individual words- agramatism.

11. Auditory Analyzer Core oral speech is closely interconnected with the cortical center of the auditory analyzer and is located in the area of ​​the superior temporal gyrus (field 43), damage to the field causes loss of the ability to understand words, speech - sensory aphasia.

12. The nucleus of the visual analyzer of written speech is located in close proximity to the nucleus of the visual analyzer - in the angular gyrus of the inferior parietal lobule (field 39). Damage to this nucleus leads to loss of the ability to perceive written text, and alexia.

Questions for self-control

1. Describe the structure of nervous tissue.

2. What are the structure of neurons?

3. Characterize the receptors.

4. Describe the nerve fibers.

5. What is a reflex arc? Name its components.

6. Explain the classification of the nervous system.

7. Describe general structure spinal cord.

8. Describe the segments of the spinal cord.

9. Spinal cord pathways.

10. What is the structure of the gray and white matter of the spinal cord?

11. Name the membranes and describe the blood supply to the spinal cord.

12. Bring general characteristics structure of the brain (surface of the brain).

13. Describe the structure, topography of the white and gray matter of the medulla oblongata and the pons.

14. Name the nuclei and centers of the medulla oblongata.

15. What is the structure of the cerebellum, features of its cortex and white matter? Topography of nuclei.

16. Give the characteristics of the IV ventricle, its relationship with the subarachnoidal space and the cavity of the III ventricle.

17. What are the structural features, components, topography of the nuclei and white matter of the midbrain?

18. Name the main parts of the diencephalon and their nuclei. Tell us about the third ventricle.

19. Telencephalon, its basal ganglia.

20. Characterize the cerebral cortex.

21. Name the furrows and gyri, the localization of functions in the cortex.

22. Characterize the white matter of the brain.

23. Name the pathways of the brain.

24. Explain the course of the fibers that make up the main ascending sensory pathways.

25. Explain the course of the fibers that make up the main descending sensory pathways.

26. Name the membranes of the brain, describe their structural and functional features.

Brain, encephalon, is placed in the cranial cavity and has a shape in general outline corresponding to the internal contours of the cranial cavity. Its superolateral, or dorsal, surface, in accordance with the cranial vault, is convex, and the lower, or base of the brain, is more or less flattened and uneven.

Three large parts can be distinguished in the brain: cerebrum (cerebrum), cerebellum (cerebellum) and brain stem (truncus encephalicus).

The largest part of the entire brain is occupied by cerebral hemispheres, followed in size by the cerebellum, the remaining, relatively small, part is the brain stem. Superolateral surface of the cerebral hemispheres. Both hemispheres are separated from each other by a fissure, fissura longitudinalis cerebri, running in the sagittal direction. In the depths of the longitudinal fissure, the hemispheres are interconnected by a commissure - the corpus callosum, corpus callosum, and other underlying formations. In front of the corpus callosum, the longitudinal fissure is through, and behind it passes into the transverse fissure of the brain, fissura transversa cerebri, separating the posterior parts of the hemispheres from the underlying cerebellum.

The lower surface of the cerebral hemispheres. From the lower surface of the brain, facies inferior cerebri, not only is visible down side the cerebral hemispheres and cerebellum, but also the entire lower surface of the brain stem, as well as the nerves extending from the brain.

The anterior section of the lower surface of the brain is represented by the frontal lobes of the hemispheres. On the lower surface of the frontal lobes, the olfactory bulbs, bulbi olfactorii, are noticeable, to which thin nerve filaments, fila olfactoria, approach from the nasal cavity through the openings of the lamina cribrosa of the ethmoid bone, which together form the first pair of cranial nerves - the olfactory nerves, nn. olfactorii. Usually, when removing the brain from the skull, these threads are torn off from the bulbus olfactorius. Olfactory bulbs continue posteriorly into the olfactory tracts, tractus olfactorii, each ending in two roots, between which there is an elevation called trigonum olfactorium. Directly behind the latter, on both sides, there is an anterior perforated substance, substantia perforata anterior, so named because of the presence of small holes here through which vessels pass into the medulla.

In the middle between both anterior perforated spaces lies the optic chiasma, chiasma opticum, shaped like the letter “X”. A thin plate extends from the upper surface of the chiasm gray, lamina terminalis, going deep into fissura longitudinalis cerebri. Behind the visual intersection is a gray tubercle, tuber cinereum; its apex is elongated into a narrow tube, the so-called funnel, infundibulum, to which the pituitary gland, hypophysis cerebri, located in the sella turcica, is suspended. Behind the gray mound there are two spherical, white elevations - the mastoid bodies, corpora mamillaria. Behind them lies a rather deep interpeduncular fossa, fossa interpeduncularis, bounded on the sides by two thick ridges converging posteriorly and called the cerebral peduncles, pedunculi cerebri. The bottom of the fossa is pierced by openings for blood vessels, and therefore is called the posterior perforated substance, substantia perforata posterior. Next to this substance, in the groove of the medial edge of the cerebral peduncle, on both sides the third paraoculomotor nerve, n. oculomotoris. On the side of the cerebral peduncles the thinnest of the cranial nerves is visible - the trochlear nerve, n. trochlearis - IV pair, which, however, does not arise from the base of the brain, but from its dorsal side, from the so-called superior medullary velum. Behind the cerebral peduncles there is a thick transverse shaft - the bridge, pons, which, tapering from the sides, plunges into the cerebellum. The lateral parts of the bridge closest to the cerebellum are called the middle cerebellar peduncles, pedunculi cerebellares medii; on the border between them and the bridge itself, the V pair emerges on both sides - the trigeminal nerve, n. trigeminus.

Behind the bridge lies the medulla oblongata, medulla oblongata; between it and the posterior edge of the bridge, on the sides of the midline, the beginning of the VI pair is visible - the abducens nerve, n.abducens; even further to the side, at the posterior edge of the middle cerebellar peduncles, two more nerves emerge side by side on both sides: VII - pair - facial nerve n. facialis, and VIII pair - n. vestibulocochlearis. Between the pyramid and the olive of the medulla oblongata, the roots of the XII pair emerge - the hypoglossal nerve, n. hypoglossus. Roots IX, X and XI pairs - n. glossopharyngeus, n. vagus and n. accessorius (upper part) - emerge from the groove behind the olive. The lower fibers of the XI pair already depart from the spinal cord in its cervical part.

“Human” signs of the structure of the brain, i.e., specific features of its structure that distinguish humans from animals.

1. Predominance of the brain over the spinal cord. Thus, in carnivores (for example, a cat) the brain is 4 times heavier than the spinal cord, in primates (for example, in macaques) it is 8 times heavier, and in humans it is 45 times heavier (the mass of the spinal cord is 30 g, the brain is 1500 g) The spinal cord makes up 22-48% of the brain mass in mammals, 5-6% in gorillas, and only 2% in humans.
2. Brain mass. In terms of absolute brain mass, a person does not take first place, since large animals have a brain heavier than a person’s (1500 g): a dolphin has 1800 g, an elephant has 5200 g, a whale has 7000 g. To reveal the true ratios of brain mass to body weight, use the so-called square brain index, i.e., the product of the absolute brain mass and the relative one. This index made it possible to distinguish man from the entire animal world. Thus, in rodents it is 0.19, in carnivores - 1.14, in cetaceans (dolphin) - 6.27, in apes - 7.35, in elephants - 9.82 and, finally, in humans - 32. 0.
3. The predominance of the cloak over the brain stem, i.e., the new brain (neencephalon) over the ancient one (paleencephalon).
4. The highest development of the frontal lobe of the cerebrum. The frontal lobes account for 8-12% of the total surface of the hemispheres in lower monkeys, 16% in anthropoid monkeys, and 30% in humans. 5. Predominance of the new cortex of the cerebral hemispheres over the old one.
5. The predominance of the cortex over the subcortex, which in humans reaches maximum figures: the cortex makes up 53.7% of the total brain volume, and the basal ganglia - only 3.7%.
6. The furrows and convolutions increase the area of ​​the gray matter cortex, so the more developed the cerebral cortex, the greater the folding of the brain. An increase in folding is achieved by the greater development of small grooves of the third category, the depth of the grooves and their asymmetrical arrangement. No animal has this at the same time large number grooves and convolutions, at the same time as deep and asymmetrical, like in humans.
7. The presence of a second signaling system, the anatomical substrate of which is the most superficial layers cerebral cortex.

To summarize, we can say that the specific features of the structure of the human brain, which distinguish it from the brain of the most highly developed animals, is the maximum predominance of the young parts of the central nervous system over the old: the brain over the spinal cord, the cloak over the trunk, the new cortex over the old, the superficial layers of the cerebral cortex over the deep ones.

The brain lies in the cranial cavity, topographic boundary with the spinal cord is the exit of the first pair of spinal nerves. His average weight up to 60 years old is 1400 g with individual variations from 1100 to 2000 g. The brain is divided into hemispheres, brainstem and cerebellum (small brain). TRUNK (truncus) includes the medulla oblongata, pons, midbrain and diencephalon. In accordance with development (the stage of three vesicles), the FOREBRAIN includes the hemispheres and diencephalon, the POSTERNUM includes the pons and cerebellum, and the RHOMBID brain includes the hindbrain and medulla oblongata. The cavities of the cerebral vesicles are transformed into the VENTRICLES of the brain (), in the left and right hemispheres the I and II ventricles are located, respectively, in the diencephalon - the III ventricle, in the rhombencephalon - the IV ventricle, the latter are connected by the Sylvian aqueduct, which is the cavity of the midbrain. The cavities of the brain are filled with cerebrospinal fluid (cerebrospinal fluid). They communicate with each other, as well as with the spinal canal and subarachnoid space. 12 pairs of cranial nerves (c/m) depart from the brain, innervating mainly the head, a number of muscles of the neck and back of the head, and also providing parasympathetic innervation of internal organs. The left and right hemispheres are separated by the longitudinal fissure (,), the bottom of which is the corpus callosum. They are separated from the cerebellum by a transverse fissure. The entire surface of the hemispheres is covered with grooves and convolutions, the largest of which is the lateral or Sylvian, it separates the frontal lobe of the hemispheres from the temporal.

AT THE BASE OF THE BRAIN () on the sides of the longitudinal fissure lie the bulbs of the olfactory nerve (1 h/m). From the bulb comes the olfactory tract, which expands into the olfactory triangle, located in the region of the anterior perforated substance (the place where it enters the brain large quantity small arteries from choroid). The longitudinal fissure on the lower surface of the hemispheres is closed in front by the terminal (end) plate, and behind it is the optic chiasm (II h/m). Behind the optic chiasm is the gray tubercle, the infundibulum with the pituitary gland, the mamillary bodies, the cerebral peduncles and the interpeduncular fossa. The bottom of the interpeduncular fossa is the posterior perforated substance. From the inside of the cerebral peduncle, the oculomotor nerve (III h/m) bends around, and from the outside - the trochlear (IV h/m) nerve. Below the cerebral peduncles, in the form of a cushion, there is a bridge that passes into the middle cerebellar peduncles, at the border with which the trigeminal nerve emerges (V h/m). In the center of the bridge, the groove of the main (basilar) artery is visible, and on the sides of it are pyramidal elevations.

Below the pons is the medulla oblongata. On its front surface there are pyramids separated by a central gap. On the sides of the pyramids there are olives, lateral to which are the lower cerebellar peduncles.

Rice. 1. External surface

IV-IV v-ventricles of the brain
1. Sylvian aqueduct
2. pinnomedullary canal
3. operculum gap
4. lateral groove
5. longitudinal slot
IA. olfactory bulb
IB. olfactory nerve
7. hug triangle
8. anterior perforated substance
II. optic chiasm
9. mamillary bodies, gray tuberosity
10A. pituitary
10V. funnel
S. gray tubercle
11. cerebral peduncles
12. interpeduncular fossa
F. frontal pole
T. temporal pole
O. occipital pole

Fig.2. Main surface

13. posterior perforated substance
III. oculomotor nerve
IV. trochlear nerve 14. bridge
15. middle cerebellar peduncle
V. trigeminal nerve
16. groove of the basilar artery
17. pyramidal elevations
18. pyramids
19. olives
20. inferior cerebellar peduncles
VI. abducens nerve
VII. facial h/m nerve
VIII. vestibulocochlear n.
IX. glossopharyngeal nerve
X. vagus nerve
X. accessory nerve
XII. hypoglossal nerve

At the border of the pons and the medulla oblongata, the abducens nerve (VI h/m), the facial nerve (VII h/m), and the vestibulocochlear nerve (VIII h/m) emerge successively from the central fissure. On the border between the olive and the inferior cerebellar peduncle are the roots of the glossopharyngeal nerve (IX h/m), vagus nerve(X h/m), accessory nerve (XI h/m), and between the pyramid and the olive the roots of the hypoglossal nerve emerge (XII h/m).

ON A SAGITTAL SECTION OF THE BRAIN (), the medial surface of the cerebral hemispheres, structures of the brain stem and cerebellum are visible. The cerebral cortex is separated by a groove from the corpus callosum. The corpus callosum is a large commissure of the brain, has a fibrous structure and has the following parts: splenium, trunk, genu, beak. The beak rests on the terminal plate; a bundle of fibers adjoins it behind, forming the anterior commissure of the brain. Under the corpus callosum there is a thin white stripe-arch, which, bending forward and downward, passes into the columns of the arch, and they, in turn, go to the mamillary bodies. Between the fornix and the corpus callosum there is a thin sagittally directed plate, a transparent septum, behind which the head of the caudate nucleus is visible.

Between the transparent septa of the two hemispheres is the fifth ventricle of the brain. All of the above formations are part of the hemispheres, and below are the structures of the trunk (). Immediately under the fornix lies the thalamus, separated by the hypothalamic sulcus from the gray tubercle, which passes downwards into the infundibulum with the pituitary gland. In front of the gray tuberosity is the optic chiasm, and behind are the mamillary bodies. The third ventricle is bounded laterally by the thalamus, below by the gray tubercle, in front by the lamina terminalis, above by the fornix, and behind by the epithalamic commissure and the epiphysis. The pineal gland lies in the epiphyseal fossa, which is limited in front by the posterior commissure of the brain.

Caudal to the thalamus are the structures of the midbrain: the quadrigeminal plate (roof), separated from the cerebral peduncles by the Sylvian aqueduct. Even lower are the sagittal sections of the bridge,

The brain is part of the central nervous system that is located inside the skull. The brain controls all functions of the body, including the rhythm of heart contractions, the ability to walk and run, and the emergence of our thoughts and emotions.

The brain consists of three main sections - posterior, middle and forebrain. The forebrain is divided into two halves - the left and right hemisphere brain

Cerebral hemispheres

Gray and white matter of the brain

The gray matter of the brain contains the bodies of nerve cells and forms the cerebral cortex, the cerebellar hemispheres and a group of subcortical nuclei.

The white matter consists of nerve fibers and is located under the cortex. Nerve fibers provide communication between the halves of the brain, as well as with the spinal cord and the entire body.

Furrows and convolutions

The calcarine sulcus marks the location of the primary visual cortex, where visual information is perceived. The primary auditory cortex is located posterior to the lateral sulcus.

On the inner surface of the temporal lobe is the primary olfactory cortex, where smell analysis occurs. Inward to the parahippocampal gyrus lies the hippocampus, which is part of the limbic system and is involved in memory formation. The areas responsible for speech are located in the dominant hemisphere (usually the left) of each individual. The motor speech center (Broca's area) is located in the posterior parts of the inferior frontal gyrus; it is necessary in the process of speech formation.

Inside the brain

Speech, thinking and motor activity

Diencephalon

These include: the thalamus, hypothalamus, as well as the epithalamus and subthalamus. The thalamus is the last way station for information from the brainstem and spinal cord before it reaches the cortex. The hypothalamus lies beneath the thalamus in the lower part of the diencephalon. It is responsible for various mechanisms of homeostasis (maintenance of life), and also controls the pituitary gland, which descends from the base of the hypothalamus. The anterior lobe of the pituitary gland secretes substances that regulate the activity of the thyroid gland, adrenal glands and ovaries and produces growth factors. The posterior lobe secretes hormones that increase blood pressure, decrease urine production, and cause uterine contractions.

The hypothalamus also influences the sympathetic and parasympathetic nervous systems and regulates body temperature, appetite, and sleep-wake patterns. The epithalamus is a relatively small part of the posterior part of the diencephalon, which includes the pineal gland (epiphysis), which synthesizes melatonin.

The subthalamus is located inferior to the thalamus next to the hypothalamus. Contains the subthalamic nucleus, which is involved in the regulation of movements.

Brain stem and cerebellum

Most of the reticular formation - the system of nerve pathways - lies in the midbrain and hindbrain. This system contains vital centers: respiratory, cardiac and vasomotor (vasomotor).

The cerebellum lies behind the hindbrain and is connected to it through three pairs of cerebral peduncles. Connections to the rest of the brain and spinal cord are made through these peduncles. The cerebellum functions at an unconscious level, coordinating movements initiated in other areas of the brain, and also provides balance, maintaining posture and muscle tone.

The human body. Outside and inside. №14 2008