Midbrain peduncles - anatomy and functions. Midbrain tegmentum Consequences of damage to the human cerebral peduncles

I – roof of the midbrain; II – midbrain tegmentum; III – base of the midbrain; 1 – superior colliculi; 2 – nucleus of the superior colliculus; 3 – gray matter of the midbrain; 4 – midbrain nucleus (V); 5 - water supply; 6 – oculomotor nucleus; 7 – Yakubovich core; 8 – Perley nucleus; 9 – corticopontine tract; 10,11 – corticospinal tracts; 12 – cortico-pontine pathway; 13 – substantia nigra; 14 – dorsal chiasm of Meynert; 15 – ventral decussation of Trout; 16 – red core; 17 – reticular formation; 18 – medial loop; 19 – side loop; 20 – nucleus of the inferior colliculus

The cerebral peduncles look like thick white ridges that emerge from the pons and go to the corresponding hemispheres of the brain. Lateral to the cerebral peduncles lie the roots of the trochlear nerve, medial to the oculomotor nerve.

In a transverse section, the cerebral peduncles are divided into the base and tegmentum of the midbrain. The boundary between them is the black substance. The base of the legs is represented by white matter; descending nerve pathways pass here. The tegmentum of the midbrain is located between the roof and the base of the legs. It contains the nerve nuclei, reticular formation, medial and lateral lemniscus, and ascending and descending nerve pathways.

One of the most important structures of the midbrain is the red nucleus. From it begins the most important path of extrapyramidal systems - the red nuclear-spinal tract, which forms a cross when leaving the nucleus and goes to the lateral cords of the spinal cord. The red nucleus regulates skeletal muscle tone. The destruction of these nuclei leads to an increase in muscle tone with a predominance of extensors.

Traditionally, the red nucleus is considered as an efferent link through which the higher parts of the extrapyramidal system exert their influence on the motor nuclei of the spinal cord and the lower part of the medulla oblongata. At the same time, one of its functions can be considered to be the conduction of nerve impulses from the cerebellum to the cerebral cortex through the thalamus.

An equally important structure of the midbrain is the substantia nigra. Its cells contain a large amount of melanin, which causes the black color. The cells of the substantia nigra produce the neurotransmitter dopamine. Damage to the substantia nigra causes disruption of fine coordinated movements (drawing, playing the violin, etc.) - the so-called “sympathetic” rigidity of the entire musculature.

Functions of the midbrain:

1. The subcortical centers of vision and hearing are located here, from which the nerve pathway departs to the spinal cord and to which the nerve pathway arrives from the spinal cord.

2. The main structures of the extrapyramidal system are located here: the red nucleus, the red nucleus-spinal cord, the substantia nigra and the reticular formation.

Parasympathetic nuclei of the oculomotor and trochlear nerves, regulating coordinated eye movements, the tone of the ciliary muscle and the tone of the muscle that constricts the pupil.

Diencephalon. Thalamus

The diencephalon is a derivative of the forebrain. It consists of: the thalamic brain - the center of afferent pathways and the hypothalamus (subthalamus region) - the highest vegetative center. The cavity of the diencephalon is the third ventricle.

The thalamic brain consists of three sections: the thalamus (thalamic thalamus), the suprathalamic region (epithalamus) and the postthalamic region (metathalamus).

Thalamus is a paired ovoid formation, the anterior part of which represents the centers of the afferent olfactory pathways, and the posterior part (cushion) – the subcortical centers of vision. The medial surfaces of both thalami are connected to each other by an interthalamic commissure, which has a cellular structure.

Thalamic nuclei are divided into groups: anterior, posterior, medial, lateral and intermediate zone nuclei.

These thalamic nuclei are divided into 3 groups:

1. Relay nuclei - nerve pathways coming from skin receptors (tactile, temperature and pain sensitivity), muscles, tendons and joints (muscular-articular sense), vision and hearing receptors are switched to them. From these nuclei, nerve fibers go to the corresponding projection areas of the cerebral cortex (cortical, central sections of the analyzers).

2. Associative nuclei - receive information from various receptors and transmit it to the associative zones of the cortex.

3. Nonspecific nuclei - are a continuation of the reticular formation, have an activating effect on the cerebral cortex.

It should be borne in mind that the thalamus performs not only relay functions, but its nuclei also take part in the primary processing of incoming information. In addition, the nuclei of the thalamus, together with other brain structures, take part in assessing the significance of incoming information and in creating the emotional coloring of sensations. It has been shown, for example, that when the functions of the thalamic nuclei are impaired, even a slight touch can be perceived as a painful irritation.

The metathalamus forms the lateral and medial geniculate bodies. The lateral lemniscus ends in the medial bodies, so they are subcortical hearing centers. Most of the fibers of the optic tract end in the lateral bodies (the other part ends in the thalamic pad), so the subcortical centers of vision are located here. The geniculate bodies are connected to the cortical centers of the corresponding analyzers.

The main part of the epithalamus is pineal gland– endocrine gland. It plays an important role in the regulation of human biological rhythms, in the regulation of puberty (inhibits the synthesis of sex hormones) and indirectly affects water-salt metabolism.

The thalamic brain contains:

1. Subcortical centers of vision and hearing.

2. Subcortical centers of smell.

3. The epiphysis is one of the endocrine glands.

4. The thalamus is the highest subcortical center of all types of sensitivity. It is responsible for the distribution of all types of sensitivity, the accuracy of localization of irritations, the accuracy of perception of the degree of irritation, and the formation of memory.

Diencephalon. Hypothalamus.

The hypothalamus forms the lower parts of the diencephalon. It includes the optic tract, optic chiasm, gray tubercle, infundibulum, mammillary bodies and the subthalamic region, which is a direct continuation of the cerebral peduncles.

Optic chiasm. It includes the optic nerves, which carry out an incomplete decussation here. The optic tracts emerge from the chiasm posteriorly. Each optic tract goes around the cerebral peduncles and ends, partly, in the pillow and in the lateral geniculate bodies, and partly in the superior colliculus.

Gray tubercle located between and slightly behind the optic tracts. Downwards it passes into the funnel, through which the hypothalamus is connected to the pituitary gland. The gray tubercle is the highest vegetative center that regulates heat exchange.

Mastoid (mamillary) bodies associated with the function of the subcortical center of smell.

In the hypothalamus, there are four main areas of accumulation of nerve cells, in which about 30 nuclei are located. These nuclei are highly differentiated, they participate in the regulation of the autonomic functions of the body and carry out the coordination and integrative activity of the sympathetic and parasympathetic parts of the nervous system. In this regard, the hypothalamus is considered the highest autonomic center.

The following are considered particularly important nuclei of the hypothalamus: supraoptic, paraventricular, inferior and superomedial nuclei, dorsal nucleus, infundibulum nucleus, medial and lateral nuclei of the mastoid body.

Biologically active compounds are produced in the neurosecretory neurons of the supraoptic and paraventricular nuclei of the hypothalamus. These include neurohormones - vasopressin (antidiuretic hormone) and oxytocin, as well as releasing factors and statins, which stimulate or inhibit the production of hormones by the pituitary gland, respectively. These compounds are transported along the processes of neurons to the pituitary gland. Neuronal processes form the pituitary stalk. Thus, the hypothalamus is connected to one of the most important endocrine glands - the pituitary gland. They are often combined into a single hypothalamic-pituitary system, which plays an important role in the regulation of the endocrine glands.

second higher education in psychology in MBA format

subject: Anatomy and evolution of the human nervous system.
Manual "Anatomy of the central nervous system"

8.1. Roof of the midbrain
8.2. Brain stems
The midbrain is a short section of the brain stem, forming the cerebral peduncles on its ventral surface and the quadrigeminal on the dorsal surface. On a cross section, the following parts are distinguished: the roof of the midbrain and the cerebral peduncles, which are divided by a black substance into the roof and the base (Fig. 8.1).

Rice. 8.1. Midbrain formations

8.1. Roof of the midbrain
The roof of the midbrain is located dorsal to the aqueduct, its plate is represented by the quadrigeminal. The hills are flat and have alternating white and gray matter. The superior colliculus is the center of vision. From it there are pathways to the lateral geniculate bodies. Due to the evolutionary transfer of vision centers to the forebrain, the centers of the superior colliculus perform only reflex functions. The inferior colliculi serve as subcortical hearing centers and are connected by the medial geniculate bodies. From the spinal cord to the quadrigeminal region there is an ascending pathway, and downwards there are pathways that provide two-way communication between the visual and auditory subcortical centers with the motor centers of the medulla oblongata and spinal cord. The motor pathways are called the tegnospinal tract and the tegnobulbar tract. Thanks to these pathways, unconscious reflex movements are possible in response to sound and auditory stimuli. It is in the buffs of the quadrigeminal that the orienting reflexes are closed, which I. P. Pavlov called the “What is this?” reflexes. These reflexes play an important role in the implementation of the mechanisms of involuntary attention. In addition, two more important reflexes are closed in the upper tubercles. This is a pupillary reflex, which ensures optimal illumination of the retina, and a reflex associated with adjusting the lens for clear vision of objects located at different distances from a person (accommodation).

8.2. Brain stems
The cerebral peduncles look like two rollers, which, diverging upward from the pons, plunge into the thickness of the cerebral hemispheres.
The tegmentum of the midbrain is located between the substantia nigra and the aqueduct of Sylvius and is a continuation of the tegmentum of the pons. It is in it that there is a group of nuclei belonging to the extrapyramidal system. These nuclei serve as intermediate links between the cerebrum on the one hand, and on the other hand, with the cerebellum, medulla oblongata and spinal cord. Their main function is to ensure coordination and automaticity of movements (Fig. 8.2).

Rice. 8.2. Transverse section of the midbrain:

1 - roof of the midbrain; 2 - water supply; 3 - central gray matter; 5 - tegmentum; 6 - red nucleus; 7 - black substance

In the tegmentum of the midbrain, the largest are the elongated red nuclei. They stretch from the subthalamic region to the pons. The red nuclei reach their greatest development in higher mammals, in connection with the development of the cerebral cortex and cerebellum. The red nuclei receive impulses from the nuclei of the cerebellum and the globus pallidus, and the axons of the neurons of the red nuclei are sent to the motor centers of the spinal cord, forming the rubrospial tract.

In the gray matter surrounding the midbrain aqueduct, there are the nuclei of the III and IV cranial nerves, innervating the oculomotor muscles. In addition, groups of vegetative nuclei are also distinguished: the accessory nucleus and the unpaired median nucleus. These nuclei belong to the parasympathetic division of the autonomic nervous system. The medial longitudinal fascicle unites the nuclei of the III, IV, VI, XI cranial nerves, which ensures combined eye movements when deviated in one direction or another and their combination with head movements caused by irritation of the vestibular apparatus.

Under the tegmentum of the midbrain is the locus coeruleus - the nucleus of the reticular formation and one of the sleep centers. Laterally from the locus coeruleus there is a group of neurons that influence the release of releasing factors (liberins and statins) of the hypothalamus.

At the border of the tegmentum with the basal part lies the substantia nigra; the cells of this substance are rich in the dark pigment melanin (where the name comes from). The substantia nigra has connections with the cortex of the frontal lobe of the cerebral hemispheres, with the nuclei of the subthalamus and reticular formation. Damage to the substantia nigra leads to disruption of fine coordinated movements associated with plastic muscle tone. The substantia nigra is a collection of neuron bodies that secrete the neurotransmitter dopamine. Among other things, dopamine appears to contribute to some pleasurable feelings. It is known to be involved in creating the euphoria for which drug addicts use cocaine or amphetamines. In patients suffering from Parkinsonism, neurons in the substantia nigra degenerate, which leads to a lack of dopamine.

The Sylvian aqueduct connects the III (diencephalon) and IV (pons and medulla oblongata) ventricles. The cerebrospinal fluid flow through it is carried out from the third to the fourth ventricle and is associated with the formation of cerebrospinal fluid in the ventricles of the hemispheres and diencephalon.
The basal part of the cerebral peduncle contains fibers of the descending pathways from the cerebral cortex to the underlying parts of the central nervous system.

The cerebral peduncle (CP) is one of two paired structures that make up the midbrain, which determines its functional purpose and importance.

Almost all chordates have a mesencephalon, which is responsible for performing vital functions that play an invaluable role in ensuring vitality, survival, pain regulation and the alternation of sleep and wakefulness.

It is also responsible for defense reflexes, protection, spatial-temporal orientation, and even for maintaining a constant body temperature, controlling movements and concentrating.

Definition of the term

The peduncles of the midbrain are located in the midbrain space, a small but significant formation, located between the posterior segment and the subcortex.

The mesencephalon, which includes several variable segments, may seem complex in structure, but in fact it is much simpler than other sections.

The difficulty in learning and remembering the device can be overcome by the old mnemonic method, in which the department is drawn in a section, in the form of an inverted head of a bear, where each base of the cerebral peduncle is bear ears, and the actual bodies of the legs in this picture are wide pieces of the muzzle of a schematically drawn animal:

Communication is achieved thanks to corticospinal fibers passing through the bases of the structure, heading to the PD cortex, and on the way back going to the spinal tract from the somato- and viscerosensory areas of the cortex.

The anatomical convention has several variations, including different concepts about the entry or separate separation of certain structural segmental formations, the presence of specific, unusual substances in them, or their independent position as the boundary between anatomical segments.

Structure	Definition 1	Definition 2
part of the cerebral peduncle located above	adjacent to the tire itself	the tire is not a separate segment, but part of the general concept of structure
Bottom and front parts of the NM	NM border the base and the cover are separate parts adjacent to the anatomical formations	the base and cover of the legs are structures separated in the first definition, and in the second they are considered an integral part
black specific substance	bordering formation between different parts of the midbrain	defined as part of the NM

If we take for granted the first distinction, in which the anatomical structure is present only as two striated ridges (smoothly emerging from under and then diverging towards different hemispheres (right and left), everything is extremely simple.

If we assume that the scientific concept includes the covering of the cerebral peduncles, the base and, which is turned with its convex side towards the base, then this is a complex structure. It is located in the mesencephalon, no less whimsical and intricate in terms of the presence of various functional devices, and is closely connected with the rest of the brain due to the specifics of its structure.

Anatomical structure and functions

The midbrain is a very small formation, contains several structures at once and is responsible for many functions, including reproduction. It would be a mistake to assume that the midbrain consists of the cerebral peduncles and the tegmentum. In addition to the base of the NM and the substantia nigra, it contains the quadrigeminal tract and the tegmentum. It is formed from a complex mesencephalic, ventral and dorsal part.

The main difficulty in considering the anatomical structure is the decision whether to include only the ridges from which the cerebral peduncles are formed, or whether to include in their composition the lid of the midbrain, the bottom and the specific substantia nigra:

1. A traditional examination will not show anything other than the body of the legs itself, with a fossa located between them (tarina or interpeduncular). It is part of the interpeduncular cistern, located at the base of the human skull, from where the midbrain receives the cerebrospinal fluid necessary for life.
2. In the interpeduncular area there is the exit of the nerve that moves the eyeball, eyelid and ensures the reaction of the pupil to a light stimulus, and on the outer surface there is the trochlear nerve, without which the movement of the oblique muscles and some characteristic turns of the eyes in the orbit are indispensable.
3. The black mass, in one interpretation – a demarcating structure, and in another – an integral part of the operating system, develops from the mesencephalon and regulates the coordination of movements. Its remarkable feature is that this is the only area of ​​the NCC in which the cells are stained with melanin.
4. The base of the NM (base of the brain) is nothing more than the lowest part located in front. There are discrepancies in determining the identity of this part not only in old anatomy textbooks, where these terms were considered equivalent or were simply not distinguished as a separate entity. Now the ONM is precisely the lower part, in which there are axons stained with myelin.
5. In contrast to the base, the tegmentum is located between the substantia nigra and the aqueduct of the brain, it forms both one and the other segments located nearby. Its structures include the red nucleus, its ventral and dorsal parts.
6. It also contains gray (periaqueductal) matter, which is anatomically classified as the tegmentum, although it is located next to the aqueduct of the brain. OSV is considered the main center of regulation of the pain symptom, going along the descending line. It is capable of projecting to the nuclei of the thalamus and spinal cord, as well as to the raphe nuclei and locus coeruleus.

The importance of anatomical formation, regardless of its composition in the first or second case, is undeniable. After all, it is precisely this that provides orientation based on the visual image and the received stimulus, ensures the maintenance of a certain body posture and the regulation of muscle tone at the reflex level.

The connection of an anatomical formation with other areas of the brain is carried out in the most variable ways - from the fibers of the corticospinal tract going to the most important analyzers (ascending and descending), to information transmitted by neurons of all adjacent formations of gray, white and black.

Consequences of damage to the peduncles of the human brain

Any damage in this area leads to the development of numerous syndromes described in the specialized literature and even named after the scientists who first recorded the phenomenon for science.

The nature of the manifestations depends on what exactly has undergone destructive changes:

• damage to the oculomotor nerve, depending on the dislocation, results in vertical nystagmus, incoordination or ophthalmoplegia of various kinds (internal total, external), Nothnagel syndrome;
• destruction of the base of the pedicle leads to paralysis of the oculomotor nerve and destruction of the pyramidal fasciculus;
• injury in this area results in cerebellar disorders, loss or impairment of the functionality of the organs of vision and hearing;
• atrophic changes in the cerebral peduncles can lead to loss of the ability to respond to external stimuli and can lead to loss of the ability to independently support life.

Being relatively small in size, the midbrain and the control and management structures located in it play a vital role in ensuring the normal functioning of the organs of hearing and vision. They are the control center for sleep and even cerebellar activity. Damage of any type - injury, appearance, failure of cerebral circulation, malignant and benign neoplasms will inevitably cause disruption of the systems for which they are responsible.

Strabismus and incoordination as a result of pathology of the oculomotor nerve are only a small part of the future complications, in which impulsive behavior and visual and tactile perceptual deceptions may appear.

Any manifestations of atrophy of brain structures are irreversible and can rarely be completely cured.

The midbrain (mesencephalon) can be considered as a continuation of the pons and the upper anterior sail. It is 1.5 cm long and consists of the peduncles (pedunculi cerebri) and the roof (tectum mesencephali), or quadrigeminal plate. The conventional boundary between the roof and the underlying tegmentum of the midbrain passes at the level of the cerebral aqueduct (Aqueduct of Sylvius), which is the cavity of the midbrain and connects the third and fourth ventricles of the brain. The cerebral peduncles are clearly visible on the ventral side of the trunk. They are two thick cords that emerge from the pons and, gradually diverging to the sides, enter the cerebral hemispheres. In the place where the cerebral peduncles depart from each other, between them there is an interpeduncular fossa (fossa interpeduncularis), closed by the so-called posterior perforated substance (substancia perforata posterior). The base of the midbrain is formed by the ventral sections of the cerebral peduncles. Unlike the base of the bridge, there are no transversely located nerve fibers and cell clusters. The base of the midbrain consists only of longitudinal efferent pathways coming from the cerebral hemispheres through the midbrain to the lower parts of the brainstem and to the spinal cord. Only a small part of them, which is part of the cortical-nuclear pathway, ends in the tegmentum of the midbrain, in the nuclei of the III and IV cranial nerves located here. The fibers that make up the base of the midbrain are arranged in a certain order. The middle part (3/5) of the base of each cerebral peduncle is composed of pyramidal and corticonuclear pathways; medial to them are the fibers of the frontopontine tract of Arnold; more laterally - fibers going to the pontine nuclei from the parietal, temporal and occipital lobes of the cerebral hemispheres - the Turk's path. Above these bundles of efferent pathways are located the structures of the tegmentum of the midbrain, containing the nuclei of the IV and III cranial nerves, paired formations related to the extrapyramidal system (substantia nigra and red nuclei), as well as structures of the reticular formation, fragments of the medial longitudinal bundles, as well as numerous conducting paths of various directions. Between the tegmentum and the roof of the midbrain there is a narrow cavity, which has a sagittal orientation and provides communication between the III and IV cerebral ventricles, called the cerebral aqueduct. The midbrain has its “own” roof - the lamina quadrigemini, which includes two lower and two upper colliculi. The posterior colliculi belong to the auditory system, the anterior ones to the visual system. Let us consider the composition of two transverse sections of the midbrain, made at the level of the anterior and posterior colliculi. Section at the level of the posterior colliculus. On the border between the base and the tectum of the midbrain, in its caudal sections, there is a medial (sensitive) loop, which soon, rising upward, diverges to the sides, giving way to the medial parts of the anterior sections of the tectum to the red nuclei (nucleus ruber), and the border with the base of the midbrain is the substantia nigra (substantia nigra). The lateral loop, consisting of conductors of the auditory pathway, in the caudal part of the tegmentum of the midbrain is displaced medially and part of it ends in the posterior tubercles of the quadrigeminal plate. The black substance has the shape of a strip - wide in the middle part, tapering at the edges. It consists of cells rich in the pigment myelin and myelin fibers, in the loops of which, as in the globus pallidus, rare large cells are located. The substantia nigra has connections with the hypothalamic region of the brain, as well as with formations of the extrapyramidal system, including the striatum (nigrostriatal tracts), the subthalamic Lewis nucleus and the red nucleus. Above the substantia nigra and inward from the medial lemniscus there are cerebellar-red nuclear tracts penetrating here as part of the superior cerebellar peduncles (decussatio pcduncularum cerebellarum superiorum), which, passing to the opposite side of the brain stem (Wernecking's decussation), end at the cells of the red nuclei. Above the cerebellar-red nuclear tract is the reticular formation of the midbrain. Between the reticular formation and the central gray matter lining the aqueduct, medial longitudinal bundles pass. These bundles begin at the level of the metathalamic part of the diencephalon, where they have connections with the nuclei of Darkshevich and the intermediate nuclei of Cajal located here. Each of the medial bundles passes along its side through the entire brain stem near the midline under the aqueduct and the bottom of the fourth ventricle of the brain. These bundles anastomose with each other and have numerous connections with the nuclei of the cranial nerves, in particular with the nuclei of the oculomotor, trochlear and abducens nerves, which ensure synchronization of eye movements, as well as with the vestibular and parasympathetic nuclei of the trunk, with the reticular formation. Next to the posterior longitudinal fasciculus runs the tectospinal tract (tractus tectospinal), starting from the cells of the anterior and posterior colliculi. Upon leaving them, the fibers of this path bend around the gray matter surrounding the aqueduct and form the decussation of Meynert (decussatio tractus tigmenti), after which the tectospinal tract descends through the underlying parts of the trunk into the spinal cord, where they end in its anterior horns at peripheral motor neurons. Above the medial longitudinal fasciculus, partly as if pressing into it, is the nucleus of the IV cranial nerve (nucleus trochlears), which innervates the superior oblique muscle of the eye. The posterior colliculi of the quadrigeminal are the center of complex unconditioned auditory reflexes; they are interconnected by commissural fibers. Each of them contains four nuclei, consisting of cells of different sizes and shapes. From the fibers of the part of the lateral loop that enters here, capsules are formed around these nuclei. Section at the level of the anterior colliculus (Fig. 11.1). At this level, the base of the midbrain appears wider than in the previous section. The crossing of the cerebellar pathways has already been completed, and on both sides of the median suture in the central part of the tegmentum, the red nuclei (nuclei rubri) dominate, in which the efferent pathways of the cerebellum, passing through the superior cerebellar peduncle (cerebellar-rednuclear pathways), mainly end. Fibers coming from the globus pallidus (fibre pallidorubraiis), from the thalamus (tractus thalamorubralis) and from the cerebral cortex, mainly from their frontal lobes (tractus frontorubralis), also fit here. From the large cells of the red nucleus, the red nucleus-spinal tract of Monakov (tractus rubrospinalis) originates, which, emerging from the red nucleus, immediately passes to the other side, forming a decussation (dicussatio fasciculi rubrospinalis) or a cross of Trout. The red nucleus spinal tract descends as part of the tegmentum of the brain stem to the spinal cord and participates in the formation of its lateral cords; it ends in the anterior horns of the spinal cord at the peripheral motor neurons. In addition, bundles of fibers extend from the red nucleus to the inferior olive of the medulla oblongata, to the thalamus, and to the cerebral cortex. In the central gray matter, under the bottom of the aqueduct, there are caudal sections of the Darkshevich nuclei and intermediate nuclei of Cajal, from which the medial longitudinal fasciculi begin. The fibers of the posterior commissure, related to the diencephalon, also originate from the Darkshevich nuclei. Above the medial longitudinal fasciculus, at the level of the superior colliculus, in the tegmentum of the midbrain are located the nuclei of the third cranial nerve. As in the previous section, on the section made through the superior colliculus, the same descending and ascending pathways pass through, which occupy a similar position here. The anterior (upper) colliculi of the quadrigeminal have a complex structure. They consist of seven alternating fibrous cell layers. There are commissural connections between them. They are also connected with other parts of the brain. Some of the fibers of the optic tract end there. The anterior colliculi are involved in the formation of unconditioned visual and pupillary reflexes. Fibers also depart from them and are included in the tegnospinal tracts belonging to the extrapyramidal system. Rice. 11.1. Section of the midbrain at the level of the cerebral peduncles and the anterior tuberculum. 1 - nucleus of the III (oculomotor) nerve; 2 - medial loop; 3 - occipital-temporal-pontine tract; 4 - substantia nigra; 5 - corticospinal (pyramidal) tract; 6 - frontal-pontine tract; 7 - red core; 8 - medial longitudinal bundle.

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Midbrain tegmentum(lat. Tegmentum mesencephalicum) - the dorsal part of the cerebral peduncle, separated by the semilunar region of the substantia nigra from the base of the peduncle. The tegmentum contains red nuclei and contains neurons of the reticular formation. The tegmentum is separated from the roof of the midbrain by the aqueduct of Sylvius.

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An excerpt characterizing the tegmentum of the midbrain

- Yes, yes, exactly. Our left flank is now very, very strong.
Despite the fact that Kutuzov kicked out all unnecessary people from the headquarters, Boris, after the changes made by Kutuzov, managed to stay at the main apartment. Boris joined Count Bennigsen. Count Bennigsen, like all the people with whom Boris was, considered the young Prince Drubetskoy an unappreciated person.
There were two sharp, definite parties in command of the army: the party of Kutuzov and the party of Bennigsen, the chief of staff. Boris was present at this last game, and no one knew better than he, while paying servile respect to Kutuzov, to make one feel that the old man was bad and that the whole business was being conducted by Bennigsen. Now the decisive moment of the battle had come, which was either to destroy Kutuzov and transfer power to Bennigsen, or, even if Kutuzov had won the battle, to make it felt that everything had been done by Bennigsen. In any case, big rewards were to be given out tomorrow and new people were to be brought forward. And as a result of this, Boris was in irritated animation all that day.