The furrows and convolutions of the brain table. The furrows and convolutions of the brain - meaning and functions. Anatomy of the human brain. Medial surface of the brain

The brain is the most advanced, and therefore one of the most difficult to study, part of the human body. And its most highly organized component is the cerebral cortex. More details about the anatomy of this formation, the structure of the grooves and convolutions of the brain later in the article.

Parts of the brain

During intrauterine development, a complex brain was formed from an ordinary neural tube. This happened due to the bulging of five brain vesicles, which gave rise to the corresponding parts of the brain:

telencephalon, or forebrain, from which the cerebral cortex, basal ganglia, and anterior part of the hypothalamus were formed;
diencephalon, or diencephalon, which gave rise to the thalamus, epithalamus, and posterior part of the hypothalamus;
mesencephalon, or midbrain, from which the quadrigeminal peduncle and cerebral peduncles subsequently formed;
the metencephalon, or hindbrain, which gave rise to the cerebellum and pons;
myelencephalon, or medulla oblongata.

Structure of the cortex

Thanks to the presence of the cortex, a person is able to experience emotions, navigate himself and the surrounding space. What is noteworthy is that the structure of the bark is unique. The grooves and convolutions of the cerebral cortex of one person have a different shape and size than that of another. But overall plan buildings one.

What is the difference between the sulci and convolutions of the brain? Fissures are depressions in the cerebral cortex that look like slits. They are the ones who divide the bark into shares. There are four lobes of the cerebral hemispheres:

frontal;
parietal;
temporal;
occipital

Gyri are convex areas of the cortex that are located between the furrows.

Formation of the cortex in embryogenesis

Embryogenesis is the intrauterine development of the fetus from conception to birth. First, uneven depressions form on the cerebral cortex, which give rise to furrows. The primary grooves are formed first. This occurs around the 10th week of intrauterine development. After this, secondary and tertiary depressions are formed.

The deepest groove is the lateral one; it is one of the first to form. It is followed in depth by the central one, which separates the motor (motor) and sensory (sensitive) zones of the cerebral cortex.

Most of the cortical relief develops from 24 to 38 weeks of gestation, and some of it continues to develop after the baby is born.

Types of furrows

The grooves are classified according to the function they perform. The following types are distinguished:

primary formed - the deepest in the brain, they divide the cortex into separate lobes;
secondary - more superficial, they perform the function of forming convolutions of the cerebral cortex;
additional, or tertiary - the most superficial of all types, their function is to provide an individual relief of the bark, increasing its surface.

Main grooves

Although the shape and size of some of the sulci and convolutions of the cerebral hemispheres differ from individual to individual, their number is normally unchanged. Every person, regardless of age and gender, has the following grooves:

Sylvian fissure - separates the frontal lobe from the temporal lobe;
lateral sulcus - separates the temporal, parietal and frontal lobes, and is also one of the deepest in the brain;
Roland's fissure - separates the frontal lobe of the brain from the parietal lobe;
parieto-occipital sulcus - separates the occipital region from the parietal;
cingulate sulcus - located on the medial surface of the brain;
circular - is the boundary for the insular part on the basal surface of the cerebral hemispheres;
The hippocampal sulcus is a continuation of the cingulate sulcus.

Main convolutions

The relief of the cerebral cortex is very complex. It consists of numerous convolutions different forms and sizes. But we can highlight the most important of them, which perform the most important functions. The main convolutions of the brain are presented below:

angular gyrus - located in the parietal lobe, involved in recognizing objects through vision and hearing;
Broca's center - rear end the inferior frontal gyrus on the left (for right-handers) or on the right (for left-handers), which is necessary for correct speech reproduction;
Wernicke's center - located in the posterior part of the superior temporal gyrus on the left or right (similar to Broca's area), is involved in the understanding of oral and written speech;
cingulate gyrus - located on the medial part of the brain, takes part in the formation of emotions;
hippocampal gyrus - located in the temporal region of the brain, on its inner surface, necessary for normal memorization;
fusiform gyrus - located in the temporal and occipital regions of the cerebral cortex, is involved in face recognition;
lingual gyrus - located in the occipital lobe, plays an important role in processing information coming from the retina;
precentral gyrus - located in the frontal lobe in front of the central sulcus, necessary for processing sensitive information entering the brain;
postcentral gyrus - located in the parietal lobe behind the central sulcus, necessary for voluntary movements.

Outside surface

The anatomy of the cerebral convolutions and sulci is best studied in sections. Let's start with the outer surface. It is on the outer surface of the brain that the deepest groove is located - the lateral one. It begins in the basal (lower) part of the cerebral hemispheres and moves to the outer surface. Here it branches into three more recesses: the ascending and anterior horizontal, which are shorter, and the posterior horizontal, which is much longer. The last branch has an upward direction. It is further divided into two parts: descending and ascending.

The bottom of the lateral groove is called the insula. It then continues as the transverse gyrus. The insula is divided into anterior and posterior lobes. These two formations are separated from each other by a central groove.

Parietal lobe

The boundaries of this part of the brain are outlined by the following grooves:

central;
parieto-occipital;
transverse occipital;
central.

Behind the central sulcus is the postcentral gyrus of the brain. At the back it is bounded by a groove with the corresponding name - postcentral. In some literary publications, the latter is further divided into two parts: upper and lower.

The parietal lobe, using the interparietal sulcus, is divided into two regions, or lobules: superior and inferior. The latter contains the supramarginal and angular gyri of the cerebral hemispheres.

In the postcentral, or posterior central, gyrus there are centers that receive sensory (sensitive) information. It is worth noting that the projection different parts the body in the posterior central gyrus is located unevenly. So, most This formation is occupied by the face and hand - the lower and middle third, respectively. The last third is occupied by projections of the torso and legs.

Praxis centers are located in the lower part of the parietal lobe. It implies the development of automatic movements throughout life. This includes, for example, walking, writing, tying shoelaces, etc.

Frontal lobe

The frontal part of the cerebral hemispheres is located in front of all other structures of the brain. Posteriorly, this area is limited from the parietal lobe by the central sulcus, and laterally, by the lateral sulcus - from the temporal region.

In front of the central sulcus is the precentral gyrus of the brain. The latter, in turn, is limited from other formations of the frontal lobe cortex by means of the precentral recess.

The precentral gyrus, together with the adjacent posterior parts of the frontal lobe, plays an important role. These structures are necessary for the implementation of voluntary movements, that is, those that are under the control of consciousness. In the fifth layer of the cortex of the precentral gyrus there are giant motor neurons, which are called pyramidal cells, or Betz cells. These neurons are very long shoot(axon), the endings of which reach the corresponding segment of the spinal cord. This pathway is called the corticospinal pathway.

The relief of the frontal region of the brain is formed by three large convolutions:

superior frontal;
average;
bottom.

These formations are delimited from one another by the superior and inferior frontal grooves.

In the posterior part of the superior frontal gyrus there is an extrapyramidal center, which is also involved in movements. This system is historically more ancient than the pyramidal one. It is necessary for accuracy and smoothness of movements, for automatic correction of motor acts that are already normal for humans.

In the posterior part of the inferior frontal gyrus there is Broca's motor center, which was already mentioned earlier in the article.

Occipital lobe

The boundaries of the occipital region of the brain are outlined by the following formations: it is separated from the parietal lobe by the parieto-occipital recess, below occipital part smoothly flows into the basal surface of the brain.

It is in this area of the brain that the most unstable structures are located. But the posterior occipital gyrus of the brain is present in almost all individuals. Moving closer to the parietal region, transitional gyri are formed from it.

On the inner surface of this area there is a calcarine groove. It separates three convolutions from each other:

wedge;
lingular gyrus;
occipitotemporal gyrus.

There are also polar grooves that have a vertical direction.

The function of the most posterior lobe of the brain is the perception and processing of visual information. It is noteworthy that the projection of the upper half of the retina of the eyeball is in the wedge, but it perceives the lower part of the visual field. And the lower half of the retina, which receives light from the upper visual field, is projected in the region of the lingual gyrus.

Temporal lobe

This structure of the brain is limited by the following grooves: the lateral one from above, a conventional line between the lateral and posterior occipital grooves at the back.

The temporal lobe, by analogy with the frontal lobe, consists of three large convolutions:

superior temporal;
average;
lower

The name of the depressions corresponds to the convolutions.

On the lower surface of the temporal region of the brain, the hippocampal gyrus and the lateral occipitotemporal gyrus are also distinguished.

Wernicke's speech center is located in the temporal lobe, which was already mentioned earlier in the article. In addition, this area of the brain performs the functions of perception of taste and olfactory sensations. It provides hearing, memory, and synthesis of sounds. Specifically, the superior temporal gyrus, as well as the inner surface of the temporal region, is responsible for hearing.

Thus, the lobes and convolutions of the brain are a complex and multifaceted topic to understand. In addition to the parts discussed in the article, there is also the limbic cortex with its own relief, a structure called the insula. There is a cerebellum, which also has a cortex with its own characteristics. But the anatomy of the brain should be studied gradually, so this article provides only basic information.

The surface of the cerebral cortex consists of folds - convolutions. They are separated by grooves; the shallow ones are called cerebral sulci, the deep ones are called cerebral fissures.

The main surface of the cloak lobes consists of grooves and convolutions. The grooves (sulci) are deep folds of the mantle containing stratified bodies of neurons - the cortex (gray matter of the mantle) and cell processes (white matter of the mantle). Between these grooves there are rollers of the cloak, which are usually called convolutions (gyri). They contain the same components as the grooves. Each section has its own permanent grooves and convolutions.

The grooves of the telencephalon are divided into three main categories, which reflect their depth, occurrence and stability of outline.

Constant (main) grooves (first order grooves). A person has 10 of them. These are the deepest folds on the surface of the brain, which change least in different people. First order furrows appear during early development and are characteristic of each animal species and humans.

Non-permanent grooves (furrows of the second order). These folds, located on the surface of the telencephalon hemispheres, have a characteristic location and direction in which they are oriented. These grooves can individually vary within very wide limits or even be absent. The depth of these grooves is quite large, but significantly less than that of the first-order grooves.

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

The shape of the grooves and convolutions has great individual variability and is a visual criterion (comparable to a fingerprint pattern) that distinguishes one person from another.

The central sulcus, sulcus centralis (Rolando), separates the frontal lobe from the parietal lobe. Anterior to it is the precentral gyrus - gyrus precentralis (gyrus centralis anterior - BNA).

Behind the central sulcus lies the posterior central gyrus - gyrus postcentralis (gyrus centralis posterior - BNA).

The lateral groove (or fissure) of the brain, sulcus (fissura - BNA) lateralis cerebri (Sylvii), separates the frontal and parietal lobes from the temporal lobe. If you separate the edges of the lateral fissure, a fossa (fossa lateralis cerebri) is revealed, at the bottom of which there is an island (insula).

The parieto-occipital sulcus (sulcus parietooccipitalis) separates the parietal lobe from the occipital lobe.

The projections of the sulci of the brain onto the integument of the skull are determined according to the scheme of cranial topography.

The core of the motor analyzer is concentrated in the precentral gyrus, and to the muscles lower limb The most highly located parts of the anterior central gyrus are related to the muscles of the oral cavity, pharynx and larynx - the most low located ones. The right-sided gyrus is connected with the motor apparatus of the left half of the body, the left-sided - with the right half (due to the intersection of the pyramidal tracts in the medulla oblongata or spinal cord).

The nucleus of the skin analyzer is concentrated in the retrocentral gyrus. The postcentral gyrus, like the precentral gyrus, is connected to the opposite half of the body.

The blood supply to the brain is carried out by systems of four arteries - internal carotid and vertebral (Fig. 5). Both vertebral arteries at the base of the skull they merge to form the basilar artery (a.basilaris), which runs in a groove on the lower surface of the medullary pons. Two aa.cerebri posteriores depart from a.basilaris, and from each a.carotis interna – a.cerebri media, a.cerebri anterior and a.communicans posterior. The latter connects a.carotis interna with a.cerebri posterior. In addition, there is an anastomosis between the anterior arteries (aa.cerebri anteriores) (a.communicans anterior). Thus, the arterial circle of Willis appears - circulus arteriosus cerebri (Willissii), which is located in the subarachnoid space of the base of the brain and extends from the anterior edge of the chiasm optic nerves to the front edge of the bridge. At the base of the skull, the arterial circle surrounds the sella turcica and at the base of the brain – the papillary bodies, the gray tubercle and the optic chiasm.

The branches that make up the arterial circle form two main vascular systems:

1) arteries of the cerebral cortex;

2) arteries of the subcortical nodes.

Of the cerebral arteries, the largest and in practical terms the most important is the middle one - a.cerebri media (otherwise - the artery of the lateral fissure of the brain). In the area of its branches, hemorrhages and embolisms are observed more often than in other areas, which was noted by N.I. Pirogov.

The veins of the brain do not usually accompany the arteries. There are two systems of them: the system of superficial veins and the system of deep veins. The former are located on the surface of the cerebral convolutions, the latter - in the depths of the brain. Both of them flow into the venous sinuses of the dura mater, and the deep ones, merging, form the large vein of the brain (v.cerebri magna) (Galeni), which flows into the sinus rectus. The great vein of the brain is a short trunk (about 7 mm), located between the thickening of the corpus callosum and the quadrigeminal.

In the system of superficial veins there are two practically important anastomoses: one connects the sinus sagittalis superior with the sinus cavernosus (Trolard vein); the other usually connects the sinus transversus to the previous anastomosis (vein of Labbé).

Rice. 5. Arteries of the brain at the base of the skull; view from above:

1 – anterior communicating artery, a.communicans anterior;

2 – anterior cerebral artery, a.cerebri anterior;

3 – ophthalmic artery, a.ophtalmica;

4 – internal carotid artery, a.carotis interna;

5 – middle cerebral artery, a.cerebri media;

6 – superior pituitary artery, a.hypophysialis superior;

7 – posterior communicating artery, a.communicans posterior;

8 – superior cerebellar artery, a.superior cerebelli;

9 – basilar artery, a.basillaris;

10 – canal of the carotid artery, canalis caroticus;

11 – anterior inferior cerebellar artery, a.inferior anterior cerebelli;

12 – posterior inferior cerebellar artery, a.inferior posterior cerebelli;

13 – anterior spinal artery, a.spinalis posterior;

14 – posterior cerebral artery, a.cerebri posterior

Scheme of cranial topography

On the integument of the skull, the position of the middle artery of the dura mater and its branches is determined by the scheme of craniocerebral (craniocerebral) topography proposed by Krenlein (Fig. 6). The same scheme makes it possible to project the most important grooves of the cerebral hemispheres onto the integument of the skull. The scheme is constructed as follows.

Rice. 6. Scheme of cranial topography (according to Krenlein-Bryusova).

ас – lower horizontal; df – average horizontal; gi – upper horizontal; ag – front vertical; bh – middle vertical; сг – back vertical.

A lower horizontal line is drawn from the lower edge of the orbit along the zygomatic arch and the upper edge of the external auditory canal. An upper horizontal line is drawn parallel to it from the upper edge of the orbit. Three vertical lines are drawn perpendicular to the horizontal ones: the anterior one from the middle of the zygomatic arch, the middle one from the joint of the lower jaw and the posterior one from the posterior point of the base of the mastoid process. These vertical lines continue to the sagittal line, which is drawn from the base of the nose to the external occipital protuberance.

The position of the central sulcus of the brain (Rolandic sulcus), between the frontal and parietal lobes, is determined by a line connecting the point of intersection; the posterior vertical with the sagittal line and the point of intersection of the anterior vertical with the upper horizontal; The central groove is located between the middle and posterior vertical.

The trunk of a.meningea media is determined at the level of the intersection of the anterior vertical and lower horizontal, in other words, immediately above the middle of the zygomatic arch. The anterior branch of the artery can be found at the level of intersection of the anterior vertical with the upper horizontal, and the posterior branch - at the level of intersection of the same; horizontal with back vertical. The position of the anterior branch can be determined differently: lay 4 cm upward from the zygomatic arch and draw a horizontal line at this level; then 2.5 cm is set back from the frontal process of the zygomatic bone and a vertical line is drawn. The angle formed by these lines corresponds to the position of the anterior branch a. meningea media.

To determine the projection of the lateral fissure of the brain (Sylvian fissure), separating the frontal and parietal lobes from the temporal lobe, the angle formed by the projection line of the central sulcus and the upper horizontal is divided by a bisector. The gap is between the front and rear vertical.

To determine the projection of the parieto-occipital sulcus, the projection line of the lateral fissure of the brain and the upper horizontal line are brought to the intersection with the sagittal line. The segment of the sagittal line enclosed between the two indicated lines is divided into three parts. The position of the groove corresponds to the boundary between the upper and middle third.

Stereotactic encephalography method (from the Greek. sterios volumetric, spatial and taxis - location) is a set of techniques and calculations that make it possible to insert a cannula (electrode) into a predetermined, deeply located structure of the brain with great accuracy. To do this, it is necessary to have a stereotactic device that compares the conventional coordinate points (systems) of the brain with the coordinate system of the apparatus, an accurate anatomical determination of intracerebral landmarks and stereotactic atlases of the brain.

The stereotaxic apparatus has opened up new prospects for studying the most inaccessible (subcortical and stem) brain structures to study their function or for devitalization in certain diseases, for example, destruction of the ventrolateral nucleus of the thalamus opticum in parkinsonism. The device consists of three parts - a basal ring, a guide arc with an electrode holder and a phantom ring with a coordinate system. First, the surgeon determines superficial (bone) landmarks, then performs a pneumoencephalogram or ventriculogram in two main projections. Using these data, in comparison with the coordinate system of the apparatus, the exact localization of intracerebral structures is determined.

On the internal base of the skull there are three stepped cranial fossae: anterior, middle and posterior (fossa cranii anterior, media, posterior). The anterior fossa is delimited from the middle fossa by the edges of the small wings of the sphenoid bone and the bone ridge (limbus sphenoidalis), lying anterior to the sulcus chiasmatis; the middle fossa is separated from the posterior dorsum of the sella turcica and the upper edges of the pyramids of both temporal bones.

The anterior cranial fossa (fossa cranii anterior) is located above the nasal cavity and both orbits. The most anterior section of this fossa, at the transition to the cranial vault, borders the frontal sinuses.

The frontal lobes of the brain are located within the fossa. On the sides of the crista galli lie the olfactory bulbs (bulbi olfactorii); the olfactory tracts begin from the latter.

Of the openings present in the anterior cranial fossa, the foramen caecum is located most anteriorly. This includes a process of the dura mater with a non-permanent emissary connecting the veins of the nasal cavity with the sagittal sinus. Posterior to this opening and to the sides of the crista galli are the openings of the perforated plate (lamina cribrosa) of the ethmoid bone, allowing passage of the nn.olfactorii and a.ethmoidalis anterior from the a.ophthalmica, accompanied by the vein and nerve of the same name (from the first branch of the trigeminal).

For most fractures in the anterior cranial fossa, the most characteristic sign is bleeding from the nose and nasopharynx, as well as vomiting of swallowed blood. Bleeding can be moderate when the vasa ethmoidalia is ruptured and severe when the cavernous sinus is damaged. Equally common are hemorrhages under the conjunctiva of the eye and eyelid and under the skin of the eyelid (a consequence of damage to the frontal or ethmoid bone). With excessive hemorrhage into the tissue of the orbit, protrusion of the eyeball (exophthalmus) is observed. The leakage of cerebrospinal fluid from the nose indicates a rupture of the processes of the meninges accompanying the olfactory nerves. If the frontal lobe of the brain is also destroyed, then particles of brain matter can escape through the nose.

If the walls are damaged frontal sinus and cells of the ethmoidal labyrinth, air may be released into subcutaneous tissue(subcutaneous emphysema) or into the cranial cavity, extra or intradurally (pneumocephalus).

Damage nn. olfactorii causes disorders of smell (anosmia) of varying degrees. Dysfunction of the III, IV, VI nerves and the first branch of the V nerve depends on the accumulation of blood in the tissue of the orbit (strabismus, pupillary changes, anesthesia of the forehead skin). As for the II nerve, it can be damaged by a fracture of the processus clinoideus anterior (at the border with the middle cranial fossa); More often there is hemorrhage in the nerve sheath.

Purulent inflammatory processes affecting the contents of the cranial fossae are often a consequence of the transition of the purulent process from the cavities adjacent to the base of the skull (orbit, nasal cavity and paranasal sinuses, inner and middle ear). In these cases, the process can spread in several ways: contact, hematogenous, lymphogenous. In particular, the transition purulent infection on the contents of the anterior cranial fossa is sometimes observed as a result of empyema of the frontal sinus and bone destruction: in this case, meningitis, epi- and subdural abscess, and abscess of the frontal lobe of the brain can develop. Such an abscess develops as a result of the spread of purulent infection from the nasal cavity along the nn.olfactorii and tractus olfactorius, and the presence of connections between the sinus sagittalis superior and the veins of the nasal cavity makes it possible for the infection to spread to the sagittal sinus.

The central part of the middle cranial fossa (fossa cranii media) is formed by the body of the sphenoid bone. It contains the sphenoid (otherwise the main) sinus, and on the surface facing the cranial cavity it has a depression - the fossa sella, in which the cerebral appendage (pituitary gland) is located. Spreading over the fossa of the sella turcica, the dura mater forms the sella diaphragm (diaphragma sellae). In the center of the latter there is a hole through which the funnel (infundibulum) connects the pituitary gland with the base of the brain. Anterior to the sella turcica, in the sulcus chiasmatis, is the optic chiasm.

In the lateral sections of the middle cranial fossa, formed by the large wings of the sphenoid bones and the anterior surfaces of the pyramids of the temporal bones, there are the temporal lobes of the brain. In addition, on the front surface of the pyramid temporal bone(on each side) at its apex (in the impressio trigemini) there is a semilunar ganglion trigeminal nerve. The cavity in which the node is placed (cavum Meckeli) is formed by a bifurcation of the dura mater. Part of the anterior surface of the pyramid forms the upper wall of the tympanic cavity (tegmen tympani).

Within the middle cranial fossa, on the sides of the sella turcica, lies one of the most important sinuses of the dura mater in practical terms - the cavernous sinus (sinus cavernosus), into which the superior and inferior ophthalmic veins flow.

Of the openings of the middle cranial fossa, the canalis opticus (foramen opticum - BNA) lies most anteriorly, through which the n.opticus (II nerve) and a.ophathlmica pass into the orbit. Between the small and large wings of the sphenoid bone, a fissura orbitalis superior is formed, through which vv.ophthalmicae (superior et inferior) pass, flowing into the sinus cavernosus, and the nerves: n.oculomotorius (III nerve), n.trochlearis (IV nerve), n. ophthalmicus (first branch of the trigeminal nerve), n.abducens (VI nerve). Immediately posterior to the superior orbital fissure lies the foramen rotundum, which passes the n.maxillaris (second branch of the trigeminal nerve), and posterior and somewhat lateral to the foramen rotundum lies the foramen ovale, through which the n.mandibularis (third branch of the trigeminal nerve) and the veins connecting the plexus pass venosus pterygoideus with sinus cavernosus. Posterior and outward from the oval foramen is the foramen spinosus, which allows the a.meningei media (a.maxillaris) to pass through. Between the apex of the pyramid and the body of the sphenoid bone there is a foramen lacerum, made of cartilage, through which the n.petrosus major (from the n.facialis) passes and often an emissary connecting the plexus pterygoideus with the sinus cavernosus. The canal of the internal carotid artery opens here.

With injuries in the area of the middle cranial fossa, as with fractures in the area of the anterior cranial fossa, bleeding from the nose and nasopharynx is observed. They arise as a result of either fragmentation of the body of the sphenoid bone, or due to damage to the cavernous sinus. Damage to the internal carotid artery running inside the cavernous sinus usually leads to fatal bleeding. There are cases when such severe bleeding does not occur immediately, and then clinical manifestation Damage to the internal carotid artery inside the cavernous sinus causes pulsating bulging eyes. It depends on the fact that blood from the damaged carotid artery penetrates the ophthalmic vein system.

When the pyramid of the temporal bone is fractured and the eardrum is ruptured, bleeding from the ear appears, and when the spurs of the meninges are damaged, cerebrospinal fluid leaks from the ear. When the temporal lobe is crushed, particles of brain matter may be released from the ear.

With fractures in the area of the middle cranial fossa, the VI, VII and VIII nerves are often damaged, resulting in internal strabismus, paralysis of the facial muscles, loss of auditory function on the losing side.

As for the spread of the purulent process to the contents of the middle cranial fossa, it can be involved in the purulent process when the infection passes from the orbit, paranasal sinuses nose and middle ear walls. An important route for the spread of purulent infection is vv.ophthalmicae, the defeat of which leads to thrombosis of the cavernous sinus and disruption of the venous outflow from the orbit. The consequence of this is swelling of the upper and lower eyelids and protrusion of the eyeball. Thrombosis of the cavernous sinus is sometimes also reflected in the nerves passing through the sinus or in the thickness of its walls: III, IV, VI and the first branch of V, more often on the VI nerve.

Part of the anterior facet of the pyramid of the temporal bone forms the roof of the tympanic cavity - tegmen tympani. If the integrity of this plate is damaged as a result of chronic suppuration of the middle ear, an abscess can form: either epidural (between the dura mater and the bone) or subdural (under the dura mater). Sometimes it develops and spills purulent meningitis or abscess of the temporal lobe of the brain. A canal adjoins the inner wall of the tympanic cavity facial nerve. Often the wall of this canal is very thin, and then the inflammatory purulent process of the middle ear can cause paresis or paralysis of the facial nerve.

Contents of the posterior cranial fossa(fossa cratiii posterior) are the pons and medulla oblongata, located in the anterior part of the fossa, on the slope, and the cerebellum, which fills the rest of the fossa.

Of the dural sinuses located in the posterior cranial fossa, the most important are the transverse sinus, which passes into the sigmoid sinus, and the occipital sinus.

The openings of the posterior cranial fossa are located in a certain sequence. Most anteriorly, on the posterior edge of the pyramid of the temporal bone lies the internal auditory opening (porus acusticus internus). The a.labyrinthi (from the a.basilaris system) and nerves pass through it - facialis (VII), vestibulocochlearis (VIII), intermedius. Next in the posterior direction is the jugular foramen (foramen jugulare), through the anterior section of which the nerves pass - glossopharyngeus (IX), vagus (X) and accessorius Willisii (XI), through the posterior section - v.jugularis interna. The central part of the posterior cranial fossa is occupied by the large occipital foramen (foramen occipitale magnum), through which passes the medulla oblongata with its membranes, aa.vertebrales (and their branches - aa.spinales anteriores et posteriores), plexus venosi vertebrales interni and the spinal roots of the accessory nerve ( n.accessorius). On the side of the foramen magnum there is a foramen canalis hypoglossi, through which n.hypoglossus (XII) and 1-2 veins pass, connecting the plexus venosus vertebralis internus and v.jugularis interna. V is located in or near the sigmoid sulcus. emissaria mastoidea, connecting the occipital vein and the veins of the external base of the skull with the sigmoid sinus.

Fractures in the posterior cranial fossa can cause subcutaneous hemorrhages behind the ear associated with damage to the sutura mastoideooccipitalis. These fractures often do not cause external bleeding, because... eardrum remains intact. The leakage of cerebrospinal fluid and the release of particles of brain matter during closed fractures not observed (no channels opening outward).

Within the posterior cranial fossa, a purulent lesion of the S-shaped sinus (sinus phlebitis, sinus thrombosis) may be observed. More often it is involved in the purulent process by contact during inflammation of the cells of the mastoid part of the temporal bone (purulent mastoiditis), but there are also cases of the purulent process transferring to the sinus when affected inner ear(purulent labyrinthitis). A thrombus developing in the S-shaped sinus can reach the jugular foramen and move to the internal bulb jugular vein. In this case, sometimes there is involvement in the pathological process of the IX, X, and XI nerves passing in the vicinity of the bulb (impaired swallowing due to paralysis of the velum and pharyngeal muscles, hoarseness, difficulty breathing and slow pulse, spasms of the sternocleidomastoid and trapezius muscles) . Thrombosis of the S-shaped sinus can also spread to the transverse sinus, which is connected by anastomosis with the sagittal sinus and with the superficial veins of the hemisphere. Therefore, the formation of blood clots in the transverse sinus can lead to an abscess of the temporal or parietal lobe of the brain.

The suppurative process in the inner ear can also cause diffuse inflammation of the meninges (purulent leptomeningitis) due to the presence of communication between the subarachnoid space of the brain and the perilymphatic space of the inner ear. When pus breaks out from the inner ear into the posterior cranial fossa through the destroyed posterior edge of the pyramid of the temporal bone, a cerebellar abscess may develop, which often occurs by contact and with purulent inflammation cells of the mastoid process. The nerves passing through the porus acusticus internus can also be conductors of infection from the inner ear.

PRINCIPLES OF OPERATIVE INTERVENTIONS IN THE CRANIAL CAVITY

Puncture of the greater occipital cistern (suboccipital puncture).

Indications. A suboccipital puncture is performed for diagnostic purposes to examine the cerebrospinal fluid at this level and to administer oxygen, air or contrast agents(lipiodol, etc.) into a large tank for the purpose of X-ray diagnostics (pneumoencephalography, myelography).

For therapeutic purposes, suboccipital puncture is used to administer various medications.

Preparation and position of the patient. The neck and lower scalp are shaved and the surgical field is prepared as usual. The patient's position is often lying on his side with a bolster under his head so that the occipital protuberance and the spinous processes of the cervical and thoracic vertebrae are on the same line. The head is tilted forward as much as possible. This increases the distance between the arch of the first cervical vertebra and the edge of the foramen magnum.

Operation technique. The surgeon feels the protuberantia occipitalis externa and the spinous process of the II cervical vertebra and in this area anesthetizes the soft tissues with 5-10 ml of a 2% novocaine solution. Exactly in the middle of the distance between the protuberantia occipitalis externa and the spinous process of the II cervical vertebra. Using a special needle with a mandrel, an injection is made along the midline in an oblique upward direction at an angle of 45-50° until the needle stops at the bottom occipital bone(depth 3.0-3.5 cm). When the tip of the needle has reached the occipital bone, it is slightly pulled back, the outer end is lifted and again pushed deep into the bone. Repeating this manipulation several times, gradually, sliding along the scales of the occipital bone, they reach its edge, move the needle anteriorly, and pierce the membrana atlantooccipitalis posterior.

The appearance of drops of cerebrospinal fluid after removing the mandrin from the needle indicates its passage through the dense atlanto-occipital membrane and entering the magna cistern. If cerebrospinal fluid containing blood comes from the needle, the puncture must be stopped. The depth to which the needle must be immersed depends on the age, gender, and constitution of the patient. On average, the puncture depth is 4-5 cm.

To protect against the risk of damage to the medulla oblongata, a special rubber attachment is put on the needle in accordance with the permissible depth of immersion of the needle (4-5 cm).

Cisternal puncture is contraindicated for tumors located in the posterior cranial fossa and in the upper cervical spinal cord.

Puncture of the ventricles of the brain (ventriculopuncture).

Indications. Ventricular puncture is performed for diagnostic and therapeutic purposes. Diagnostic puncture is used to obtain ventricular fluid for the purpose of its examination, to determine intraventricular pressure, to administer oxygen, air or contrast agents (lipiodol, etc.).

Therapeutic ventriculopuncture is indicated if urgent unloading of the cerebrospinal fluid system is necessary when it is blocked, to remove fluid from the ventricular system for a longer time, i.e. for long-term drainage of the liquor system, as well as for the administration of medications into the ventricles of the brain.

Puncture of the anterior horn lateral ventricle brain

For orientation, first draw a midline from the bridge of the nose to the occipital protuberance (corresponding to the sagittal suture) (Fig. 7A,B). Then mark the line of the coronal suture, located 10-11 cm above the brow ridge. From the intersection of these lines, 2 cm to the side and 2 cm anterior to the coronal suture, points for craniotomy are marked. A linear soft tissue incision 3-4 cm long is made parallel to the sagittal suture. The periosteum is peeled off with a raspatory and a hole is drilled in the frontal bone with a milling cutter at the intended point. Having cleaned the edges of the hole in the bone with a sharp spoon, a 2 mm long incision in the dura mater is made in the avascular area with a sharp scalpel. Through this incision, a special blunt cannula with holes on the sides is used to puncture the brain. The cannula is advanced strictly parallel to the large falciform process with an inclination in the direction of the biauricular line ( conditional line, connecting both ear canal) to a depth of 5-6 cm, which is taken into account on the scale marked on the surface of the cannula. When the required depth is reached, the surgeon firmly fixes the cannula with his fingers and removes the mandrel from it. The liquid is normally transparent and is released in rare drops. With dropsy of the brain, cerebrospinal fluid sometimes flows in a stream. Having removed the required amount of cerebrospinal fluid, the cannula is removed and the wound is sutured tightly.

Rice. 7. Scheme of puncture of the anterior and posterior horns of the lateral ventricle of the brain.

A – location of the burr hole in relation to the coronal and sagittal sutures outside the projection of the sagittal sinus;

B – the needle is passed through the burr hole to a depth of 5-6 cm in the direction of the biauricular line;

C – location of the burr hole in relation to the midline and the level of the occipital protuberance (the direction of the needle stroke is indicated in the box);

D – the needle is passed through the burr hole into the posterior horn of the lateral ventricle. (From: Gloomy V.M., Vaskin I.S., Abrakov L.V. Operative neurosurgery. - L., 1959.)

Puncture of the posterior horn of the lateral ventricle of the brain

The operation is performed according to the same principle as puncturing the anterior horn of the lateral ventricle (Fig. 7 C,D). First, set a point located 3-4 cm above the occipital buff and 2.5-3.0 cm from the midline to the left or right. This depends on which ventricle is intended to be punctured (right or left).

Having made a trepanation hole at the indicated point, cut through a short distance of the hard meninges, after which a cannula is inserted and moved anteriorly 6-7 cm in the direction of an imaginary line running from the injection site to the upper outer edge of the orbit of the corresponding side.

Stopping bleeding from the venous sinuses.

With penetrating wounds of the skull, sometimes dangerous bleeding from the venous sinuses of the dura mater, most often from the superior sagittal sinus and less often from the transverse sinus. Depending on the nature of the sinus injury, various methods of stopping bleeding are used: tamponade, suturing and sinus ligation.

Tamponade of the superior sagittal sinus.

Primary surgical treatment of the wound is performed, and a sufficiently wide (5-7 cm) trepanation hole is made in the bone so that intact areas of the sinus are visible. If bleeding occurs, the hole in the sinus is pressed with a tampon. Then they take long gauze strips, which are methodically placed in folds over the bleeding area. Tampons are inserted on both sides of the sinus injury site, placing them between the inner plate of the skull bone and the dura mater. Tampons press the upper wall of the sinus to the lower, causing it to collapse and subsequently form a blood clot in this place. The tampons are removed after 12-14 days.

For small defects in the outer wall of the venous sinus, the wound can be closed with a piece of muscle (for example, temporalis) or a plate of galea aponeurotica, which is sutured with separate frequent or, better, continuous sutures to the dura mater. In some cases, it is possible to close the sinus wound with a flap cut from the outer layer of the dura mater according to Burdenko. Applying a vascular suture to the sinus is possible only with small linear breaks its upper wall.

If it is impossible to stop the bleeding using the above methods, both ends of the sinus are tied with strong silk ligatures on a large round needle.

Ligation of the superior sagittal sinus.

Temporarily holding back the bleeding by pressing with the index finger or a tampon, quickly expand the defect in the bone with pliers so that the upper longitudinal sinus is open to a sufficient extent. After this, departing from the midline by 1.5-2.0 cm, the dura mater is incised on both sides parallel to the sinus anterior and posterior to the site of injury. Through these incisions, two ligatures are inserted with a thick, sharply curved needle to a depth of 1.5 cm and the sinus is bandaged. Then all the veins flowing into the damaged area of the sinus are ligated.

Dressing a. meningea media.

Indications. Closed and open damage skull, accompanied by injury to the artery and the formation of an epidural or subdural hematoma.

The projection of the branches of the middle meningeal artery is determined based on the Krenlein diagram. By general rules craniotomy, a horseshoe-shaped skin-aponeurotic flap with a base on the zygomatic arch is cut out in the temporal region (on the damaged side) and it is scalped downwards. After this, the periosteum is dissected within the skin wound, several holes are drilled in the temporal bone with a milling cutter, a musculoskeletal flap is formed and broken at the base. Blood clots are removed with a swab and the bleeding vessel is found. Having found the site of damage, they grab the artery above and below the wound with two clamps and bandage it with two ligatures. If there is a subdural hematoma, the dura mater is dissected and carefully removed with a jet saline solution blood clots, drain the cavity and produce hemostasis. Sutures are placed on the dura mater. The flap is placed in place and the wound is sutured in layers.

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. On top, 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 has great value in the regulation of the body’s vital functions, in the implementation of complex forms of behavior and the formation 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. The premotor cortex contains motor centers associated with social functions human: the center of written speech in the posterior part of the middle frontal gyrus, the Broca motor speech center in the posterior part of the inferior frontal gyrus, providing speech, as well as the musical motor center, providing the tone of speech, 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, mechanical element of writing, various types labor activity(for example, the driver’s movements while driving, 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 gyrus). 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 tasteful.

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 unites into a single functional system- 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. Extended middle part 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.

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 - top 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 gyri.