Medial longitudinal bundle. Midbrain Development
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midbrain(mesencephalon) develops from the middle brain bladder and is part of the brain stem. On the ventral side, the posterior surface of the mastoid bodies adjoins it in front and the anterior edge of the bridge behind (). On the dorsal surface, the anterior border of the midbrain is the level of the posterior commissure and the base of the pineal gland (pineal gland), and the posterior border is the anterior margin of the medullary velum. The structure of the midbrain includes the legs of the brain and the roof of the midbrain (Fig. 3.27; Atl.). The cavity of this part of the brain stem is plumbing of the brain a narrow canal that communicates with the fourth ventricle from below, and from above with the third (Fig. 3.27). In the midbrain there are subcortical visual and auditory centers and pathways connecting the cerebral cortex with other brain formations, as well as pathways passing through the midbrain and their own pathways.
1 - the third ventricle;
2 - epiphysis (pulled);
3 - pillow of the thalamus;
4 - lateral geniculate body;
5 - handle of the upper colliculus (6);
7 - leash;
8 - leg of the brain;
9 - medial geniculate body;
10 - lower colliculus and
11 - his handle;
12 - bridge;
13 - upper medullary sail;
14 - superior cerebellar peduncle;
15 - the fourth ventricle;
16 - lower legs of the cerebellum;
17 - middle cerebellar peduncle;
IV - cranial nerve root
The quadrigemina, or the roof of the midbrain
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four hills, or midbrain roof (tectum mesencephali)(Fig. 3.27) is divided by grooves perpendicular to each other into upper and lower hillocks. They are covered by the ridge of the corpus callosum and the cerebral hemispheres. On the surface of the mounds is a layer of white matter. Below it in the upper colliculus lie layers of gray matter, and in the lower Gray matter forms nuclei. On neurons, gray matter ends and some pathways begin from them. The right and left hillocks in each colliculus are connected by commissures. Laterally depart from each mound knoll handles, which reach the geniculate bodies of the diencephalon.
Superior colliculus
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Superior colliculus contains centers of orienting reflexes to visual stimuli. The fibers of the optic tract reach the lateral geniculate bodies, and then some of them along handles of the superior colliculus continues into the superior tubercles of the quadrigemina, the rest of the fibers go to the thalamus.
inferior colliculus
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inferior colliculus serves as the center of orienting reflexes to auditory stimuli. From the mounds go forward and outward handles, ending at the medial geniculate bodies. Hillocks take part of the fibers lateral loop, the rest of its fibers go as part of the handles of the lower colliculus to the medial geniculate body.
Tectospinal pathway
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Originates from the roof of the midbrain tectospinal path. Its fibers after cross in the tegmentum of the midbrain they go to the motor nuclei of the brain and to the cells of the anterior horns of the spinal cord. The path conducts efferent impulses in response to visual and auditory stimuli.
Preopercular nuclei
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On the border of the midbrain and diencephalon lie preopercular(pretectal) core, having connections with the superior colliculus and parasympathetic nuclei of the oculomotor nerve. The function of these nuclei is the synchronous reaction of both pupils when the retina of one eye is illuminated.
Legs of the brain
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Brain peduncles (pedunculi cerebri) occupy the anterior part of the midbrain and are located above the bridge. Between them, the roots of the oculomotor nerve (III pair) appear on the surface. The legs consist of a base and a tire, which are separated by highly pigmented cells of the substantia nigra (see Atl.).
V base of legs passes the pyramidal path, consisting of corticospinal, heading across the pons to the spinal cord, and cortical-nuclear, the fibers of which reach the neurons of the motor nuclei of the cranial nerves located in the region of the fourth ventricle and the aqueduct, as well as cortical-bridge path, ending on the cells of the base of the bridge. Since the base of the legs consists of descending pathways from the cerebral cortex, this part of the midbrain is the same phylogenetically new formation as the base of the pons or pyramid of the medulla oblongata.
black substance
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black substance separates the base and cover of the legs of the brain. Its cells contain the pigment melanin. This pigment exists only in humans and appears at the age of 3-4 years. The substantia nigra receives impulses from the cerebral cortex, striatum, and cerebellum and transmits them to the neurons of the superior colliculus and brainstem nuclei, and then to the motor neurons of the spinal cord. The substantia nigra plays an essential role in the integration of all movements and in the regulation of the plastic tone of the muscular system. Violation of the structure and function of these cells causes parkinsonism.
Leg cover
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Leg cover continues the tegmentum of the pons and medulla oblongata and consists of phylogenetically ancient structures. Its upper surface serves as the bottom of the aqueduct of the brain. The cores are located in the tire bloc(iv) and oculomotor(III) nerves. These nuclei develop in embryogenesis from the main plate, which lies under the borderline groove, consist of motor neurons and are homologous to the anterior horns of the spinal cord. Lateral to the aqueduct along the entire midbrain stretches nucleus of the mesencephalic tract trigeminal nerve. It receives proprioceptive sensitivity from the muscles of mastication and the muscles of the eyeball.
Medial longitudinal bundle
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Beneath the gray matter surrounding the plumbing, from neurons intermediate nucleus the phylogenetically old way begins - medial longitudinal bundle. It contains fibers that connect the nuclei of the oculomotor, trochlear and abducens nerves. Fibers also join the bundle, starting from the nucleus of the nerve of the vestibule (VIII) and carrying impulses to the nuclei of the III, IV, VI and XI cranial nerves, as well as descending to the motor neurons of the spinal cord. The bundle passes into the bridge and the medulla oblongata, where it lies under the bottom of the fourth ventricle near the midline, and then into the anterior column of the spinal cord. Due to such connections, when the balance apparatus is stimulated, the eyes, head and limbs are set in motion.
red core
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In the region of the nuclei of the third pair of nerves lies the parasympathetic nucleus; it develops at the site of the border furrow and consists of intercalary neurons of the autonomic nervous system. In the upper part of the tegmentum of the midbrain, a dorsal longitudinal bundle passes, connecting the thalamus and hypothalamus with the nuclei of the brainstem.
At the level of the inferior colliculus, cross fibers of the superior cerebellar peduncle. Most of them end in massive cell clusters lying in front - red nuclei (nucleus ruber), and a smaller part passes through the red nucleus and continues to the thalamus, forming dentate-thalamic pathway.
In the red nucleus, fibers from the cerebral hemispheres also terminate. From its neurons there are ascending paths, in particular, to the thalamus. The main downward path of the red nuclei is rubro-spinal (red-nuclear-spinal). Its fibers, which immediately cross out of the nucleus, are directed along the tires of the brain stem and the lateral funiculus of the spinal cord to the motor neurons of the anterior horns of the spinal cord. In lower mammals, this path transmits to them, and then to the musculature of the body, impulses switched in the red nucleus, mainly from the cerebellum. In higher mammals, the red nuclei function under the control of the cerebral cortex. They are an important part of the extrapyramidal system that regulates muscle tone and has an inhibitory effect on the structures of the medulla oblongata.
The red nucleus consists of large and small cells. The large cell part is developed to a large extent in lower mammals, while the small cell part is developed in higher mammals and in humans. The progressive development of the small cell part proceeds in parallel with the development of the forebrain. This part of the nucleus is, as it were, an intermediate node between the cerebellum and the forebrain. The large cell part in humans is gradually reduced.
Lateral to the red nucleus in the tire is located medial loop. Between it and the gray matter surrounding the plumbing lie nerve cells and fibers. reticular formation(continuation of the reticular formation of the bridge and the medulla oblongata) and pass the ascending and descending paths.
Midbrain Development
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The midbrain develops in the process of evolution under the influence of visual afferentation. In lower vertebrates, in which the cerebral cortex is almost absent, the midbrain is highly developed. It reaches a considerable size and, together with the basal ganglia, performs the functions of a higher integrative center. However, only the superior colliculus is developed in it.
In mammals, in connection with the development of hearing, in addition to the upper ones, the lower tubercles also develop. In higher mammals, and especially in humans, in connection with the development of the cerebral cortex, the higher centers of visual and auditory functions pass into the cortex. In this case, the corresponding centers of the midbrain are in a subordinate position.
The medial (posterior) longitudinal bundle (fasciculis longitudinalis medialis) is a paired formation, complex in composition and function, starting from the nucleus of Darkshevich and the intermediate nucleus of Cajal at the level of the metathalamus. The medial longitudinal bundle passes through the entire brainstem near the midline, ventral to the central periaqueductal gray matter, and under the floor of the IV ventricle of the brain penetrates into the anterior cords of the spinal cord, ending at the cells of its anterior horns at the cervical level. It is a collection of nerve fibers belonging to various systems. It consists of descending and ascending pathways that connect paired cellular formations of the brain stem, in particular, nuclei III, IV and VI of the cranial nerves that innervate the muscles that provide eye movements, as well as the vestibular nuclei and cellular structures that make up the reticular formation, and anterior horns of the cervical spinal cord. Due to the associative function of the medial longitudinal fascicle, normal movements of the eyeballs are always friendly, combined. Involvement of the medial longitudinal fascicle in the pathological process leads to the emergence of various oculovestibular disorders, the nature of which depends on the localization and prevalence of the pathological focus. The defeat of the medial longitudinal beam can cause various forms of gaze disorder, strabismus and nystagmus. Damage to the medial bundle often occurs with severe traumatic brain injury, with impaired blood circulation in the brain stem, with its compression as a result of wedging of the structures of the mediobasal parts of the temporal lobe into the Bish fissure (the gap between the edge of the notch of the cerebellum and the brain stem), with compression of the brain stem by a tumor subtentorial localization, etc. (Fig. 11.5). With damage to the medial longitudinal beam, the following syndromes are possible. Gaze paresis - a consequence of a violation of the functions of the medial beam - the impossibility or limitation of friendly rotation of the eyeballs in one direction or another horizontally or vertically. To assess the mobility of the patient's gaze, they are asked to follow an object moving horizontally and vertically. Normally, when turning the eyeballs to the sides, the lateral and medial edges of the cornea should touch the outer and inner commissures of the eyelids, respectively, or approach them at a distance of no more than 1-2 mm. Rotation of the eyeballs down is normally possible by 45°, up - by 45-20°, depending on the age of the patient. Gaze paresis in the vertical plane is usually the result of damage to the midbrain tegmentum and metathalamus at the level of the posterior commissure of the brain and the part of the medial longitudinal bundle located at this level. Rice. 11.5. Innervation of the eye muscles and medial longitudinal bundles, providing their connections with each other and with other brain structures. I - the nucleus of the oculomotor nerve; 2 - accessory nucleus of the oculomotor nerve (Yakubovich-Edinger-Westphal nucleus); 3 - posterior central nucleus of the oculomotor nerve (Perlia's nucleus), 4 - ciliary node; 5 — a kernel of a block nerve; 6 - the core of the efferent nerve; 7 - own nucleus of the medial longitudinal bundle (Darkshevich's nucleus); 8 - medial longitudinal bundle; 9 - adversive center of the premotor zone of the cerebral cortex; 10 - lateral vestibular nucleus. Damage syndromes 1a and 16 - large cell nucleus of the oculomotor (111) nerve, II - accessory nucleus of the oculomotor nerve; III - nuclei of the IV nerve; IV - nuclei of the VI non-moat; V and VI - damage to the right adversive field or the left bridge center of gaze Paths that provide friendly eye movements are marked in red. Gaze paresis in the horizontal plane develops when the covering of the bridge is damaged at the level of the nucleus of the VI cranial nerve, the so-called pontine center of gaze (gaze paresis towards the pathological process). Paresis of the gaze in the horizontal plane also occurs when the cortical center of the gaze, located in the posterior part of the middle frontal gyrus, is damaged. In this case, the eyeballs are turned towards the pathological focus (the patient "looks" at the focus). Irritation of the cortical center of gaze may be accompanied by a combined turn of the eyeballs in the direction opposite to the pathological focus (the patient "turns away" from the focus), as is sometimes the case, for example, during an epileptic seizure. The symptom of floating eyes is that in patients in a coma in the absence of paresis of the eye muscles due to dysfunction of the medial fascicles, the eyes spontaneously make floating movements. They are slow in pace, non-rhythmic, chaotic, can be both friendly and asynchronous, appear more often in the horizontal direction, however, individual movements of the eyes in the vertical direction and diagonally are also possible. With floating movements of the eyeballs, the oculocephalic reflex is usually preserved. These eye movements are the result of gaze disorganization and cannot be reproduced arbitrarily, always indicating the presence of a pronounced organic brain pathology. With severe inhibition of stem functions, floating eye movements disappear. The Hertwig-Magendie symptom is a special form of acquired strabismus, in which the eyeball on the side of the lesion is turned downward and inward, and the other upward and outward. This dissociated position of the eyes persists even with changes in the position of the gaze. The symptom is caused by a lesion of the medial longitudinal bundle in the midbrain tegmentum. It often occurs as a result of circulatory disorders in the brain stem, it is possible with tumors of subtentorial localization or traumatic brain injury. Described in 1826 by the German physiologist K.N. Hertwig (1798-1887) and in 1839 the French physiologist F. Magendie (1783-1855). Internuclear ophthalmoplegia is a consequence of unilateral damage to the medial longitudinal fasciculus in the tegmentum of the brain stem in the area between the middle part of the bridge and the nuclei of the oculomotor nerve and the resulting deefferentation of these nuclei. Leads to impaired gaze (friendly movements of the eyeballs) due to a disorder of the innervation of the ipsilateral internal (medial) rectus muscle of the eye. As a result, paralysis of this muscle occurs and the inability to turn the eyeball in the medial direction beyond the midline or moderate (subclinical) paresis, leading to a decrease in the speed of adduction of the eye (to its adduction delay), while on the opposite side of the affected medial longitudinal bundle side usually there is a monocular abduction nystagmus. The convergence of the eyeballs is preserved. With unilateral internuclear ophthalmoplegia, the eyeballs may diverge in the vertical plane, in such cases the eye is located higher on the side of the lesion of the medial longitudinal fasciculus. Bilateral internuclear ophthalmoplegia is characterized by paresis of the muscle that adducts the eyeball on both sides, a violation of friendly eye movements in the vertical plane and turns of the gaze when checking the oculocephalic reflex. Damage to the medial longitudinal fascicle in the anterior part of the midbrain can also lead to a violation of the convergence of the eyeballs. The cause of internuclear ophthalmoplegia can be multiple sclerosis, circulatory disorders in the brainstem, metabolic intoxications (in particular, with paraneoplastic syndrome), etc. Lutz syndrome is a variant of internuclear ophthalmoplegia, characterized by supranuclear abduction paralysis, in which voluntary movements are disturbed eyes outward, but reflexively, with caloric stimulation of the vestibular apparatus, its complete abduction is possible. Described by the French doctor N. Lutz. Semimountain syndrome is a combination of bridging gaze paresis in one direction and manifestations of internuclear ophthalmoplegia when looking in the other direction. The anatomical basis of the one-and-a-half syndrome is a combined lesion of the ipsilateral medial longitudinal fasciculus and the pontine center of gaze or the pontine paramedian reticular formation. The clinical picture is based on impaired eye movements in the horizontal plane with preserved vertical excursion and convergence. The only possible movement in the horizontal plane is the abduction of the eye opposite to the pathological focus, with the occurrence of its mononuclear abduction nystagmus with the complete immobility of the eye, ipsilateral to the pathological focus. The name "one and a half" has the following origin: if the usual friendly movement in one direction is taken as 1 point, then the gaze movements in both directions are 2 points. With one and a half syndrome, the patient retains the ability to avert only one eye, which corresponds to 0.5 points from the normal range of eye movements in the horizontal plane. Consequently, 1.5 points are lost. Described in 1967 by the American neurologist S. Fisher. The oculocephalic reflex (the "doll's head and eyes" phenomenon, the "doll's eyes" test, Cantelli's symptom) is a reflex deviation of the eyeballs in the opposite direction when the patient's head turns in the horizontal and vertical planes, which are carried out by the examiner first slowly, and then quickly (do not check if you suspect damage to the cervical spine!). After each turn, the patient's head should be held in the extreme position for some time. These gaze movements are carried out with the participation of stem mechanisms, and the sources of impulses going to them are the labyrinth, vestibular nuclei and cervical proprioceptors. In patients in a coma, the test is considered positive if the eyes, when checking it, move in the direction opposite to the turn of the head, maintaining their position in relation to external objects. A negative test (lack of eye movements or their discoordination) indicates damage to the pons or midbrain or barbiturate poisoning. Normally, reflex gaze movements when checking the oculocephalic reflex in an awake person are suppressed. With intact consciousness or its slight suppression, the vestibular reflex, which causes the phenomenon, is completely or partially suppressed, and the integrity of the structures responsible for its development is checked by inviting the patient to fix his gaze on a certain object, while passively turning his head. In the case of a drowsy state of the patient in the process of checking the oculocephalic reflex, during the first two or three turns of the head, friendly turns of the gaze in the opposite direction occur, but then disappear, since the test leads to the awakening of the patient. Described Cantelli's disease. convergent nystagmus. It is characterized by spontaneous slow divergent movements of the drift type, interrupted by fast convergent shocks. Occurs when the midbrain tegmentum and its connections are damaged, may alternate with retraction nystagmus. Described in 1979 by Ochs et al. Vestibulo-ocular reflex - reflex coordinated movements of the eyeballs, ensuring that the fixation point is kept in the zone of the best vision in cases of changes in head position, as well as changes in gravity and acceleration. Carried out with the participation of the vestibular system and cranial nerves that innervate the muscles that provide gaze movements
11.1. MIDBRAIN
midbrain (mesencephalon) can be seen as a continuation of the bridge and the upper headsail. It has a length of 1.5 cm, consists of the legs of the brain (pedunculi cerebri) and roofs (tectum mesencephali), or plates of the quadrigemina. The conditional boundary between the roof and the underlying tegmentum of the midbrain runs at the level of the aqueduct of the brain (Sylvian aqueduct), which is the cavity of the midbrain and connects the III and IV ventricles of the brain.
The cerebral peduncles are clearly visible on the ventral side of the brainstem. They are two thick strands that come out of the substance of the bridge and, gradually diverging to the sides, enter the cerebral hemispheres. In the place where the legs of the brain move away from each other, between them is the 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 legs of the brain. Unlike the base of the bridge, there are no transversely located nerve fibers and cell clusters. The base of the midbrain is made up only of longitudinal efferent pathways 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 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 leg of the brain is made up of pyramidal and cortical-nuclear pathways; more medially from them are the fibers of the frontal-bridge path of Arnold; laterally - fibers going to the nuclei of the bridge from the parietal, temporal and occipital lobes of the cerebral hemispheres - the path of the Turk.
Above these bundles of efferent pathways are structures of the midbrain tegmentum containing the nuclei of the IV and III cranial nerves, paired formations related to the extrapyramidal system (black substance and red nuclei), as well as structures of the reticular formation, fragments of medial longitudinal bundles, as well as numerous conductive paths of various directions.
Between the tire 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 aqueduct of the brain.
The midbrain has its own roof - the plate of the quadrigemina (lamina quadrigemini), which consists of two lower and two upper mounds. The posterior colliculi belong to the auditory system, the anterior colliculi to the visual system.
Consider the composition of two transverse sections of the midbrain taken at the level of the anterior and posterior colliculi.
Cut at the level of the posterior colliculus. On the border between the base and the tegmentum of the midbrain, in its caudal sections, there is a medial (sensitive) loop, which soon, rising up, diverges to the sides, giving way to the medial parts of the anterior parts of the tegmentum red nuclei (nucleus ruber), and the border with the base of the midbrain - black substance (substancia nigra). The lateral loop, consisting of conductors of the auditory pathway, in the caudal part of the tegmentum of the midbrain is displaced inwards and part of it ends in the posterior tubercles of the quadrigemina plate.
The black substance has the form of a strip - wide in the middle part, tapering along the edges. It consists of cells rich in myelin pigment, and myelin fibers, in the loops of which, as in the pale ball, there are rare large cells. The substantia nigra has connections with the hypothalamic part of the brain, as well as with the formations of the extrapyramidal system, including the striatum (nigrostriatal pathways), the Lewis subthalamic nucleus and the red nucleus.
Above the black substance and medially from the medial loop, there are cerebellar-red nuclear pathways penetrating here in the composition of the upper cerebellar peduncles (decussatio peduncularum cerebellarum superiorum), which, passing to the opposite side of the brain stem (Wernecking's cross), end at the cells of the red nuclei.
Above the cerebellar-red nuclear pathways is the reticular formation of the midbrain. Between the reticular formation and the central gray matter lining the aqueduct, there are medial longitudinal bundles. These bundles begin at the level of the metathalamic part of the diencephalon, where they have connections with the nuclei of Darkshevich located here and the intermediate nuclei of Cajal. 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 IV 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 synchronism of eye movements, as well as with the vestibular and parasympathetic nuclei of the trunk, with the reticular formation. Near the posterior longitudinal bundle passes the tectospinal tract (tractus tectospinalis), starting from the cells of the anterior and posterior colliculi of the quadrigemina. Upon exiting them, the fibers of this path go around the gray matter surrounding the water supply and form the Meinert cross. (decussatio tractus tigmenti), after which the operculospinal tract descends through the underlying sections of the trunk into the spinal cord, where it ends in its anterior horns at peripheral motor neurons. Above the medial longitudinal bundle, partly as if pressed into it, is the nucleus of the IV cranial nerve (nucleus trochlearis), innervates the superior oblique muscle of the eye.
The posterior colliculi of the quadrigemina are the center of complex unconditioned auditory reflexes, they are interconnected by commissural fibers. Each of them contains four nuclei, consisting of different sizes
Rice. 11.1.Section of the midbrain at the level of the cerebral peduncles and anterior colliculus. 1 - core III (oculomotor) nerve; 2 - medial loop; 3 - occipital-temporal-bridge path; 4 - black substance; 5 - cortico-spinal (pyramidal) path; 6 - frontal bridge path; 7 - red core; 8 - medial longitudinal bundle.
and cell shape. From the fibers of the part of the lateral loop included here, capsules are formed around these nuclei.
Cut at the level of the anterior colliculus (fig.11.1). At this level, the base of the midbrain is wider than in the previous section. The intersection of the cerebellar pathways has already been completed, and red nuclei dominate on both sides of the median suture in the central part of the tegmentum. (nuclei rubri), in which the efferent pathways of the cerebellum mainly end, passing through the superior cerebellar peduncle (cerebellar red nuclear pathways). The fibers coming from the pale ball are also suitable here. (fibre pallidorubralis), from the thalamus (tractus thalamorubralis) and from the cerebral cortex, mainly from their frontal lobes (tractus frontorubralis). Monakov's red nuclear-spinal tract originates from large cells of the red nucleus. (tractus rubrospinalis), which, leaving the red core, immediately passes to the other side, forming a cross (dicussatio fasciculi rubrospinalis) or Trout cross. The red nuclear-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 in peripheral motor neurons. In addition, bundles of fibers depart from the red nucleus to the lower olive of the medulla oblongata, to the thalamus, to the cerebral cortex.
In the central gray matter under the bottom of the aqueduct, there are the caudal sections of the Darkshevich nuclei and the intermediate Cajal nuclei, from which the medial longitudinal bundles begin. The posterior commissure fibers related to the diencephalon also originate from the Darkshevich nuclei. Above the medial longitudinal bundle at the level of the superior tubercles of the quadrigemina in the tegmentum of the midbrain are the nuclei of the III cranial nerve. As on
In the previous section, on the section made through the superior colliculus, the same descending and ascending pathways pass, which occupy a similar position here.
The anterior (superior) colliculi of the quadrigemina have a complex structure. They consist of seven fibrous cell layers alternating with each other. There are commissural links between them. They are connected with other parts of the brain. They end part of the fibers of the optic tract. The anterior colliculus is involved in the formation of unconditioned visual and pupillary reflexes. Fibers also depart from them, which are included in the cerebrospinal tracts related to the extrapyramidal system.
11.2. CRANIAL NERVES OF THE MIDBRAIN
11.2.1. Block (IV) nerve (n. trochlearis)
Block nerve (n. trochlearis, IV cranial nerve) is motor. It innervates only one striated muscle - the superior oblique muscle of the eye. (m. obliquus superior), turning the eyeball down and slightly outward. Its nucleus is located in the tegmentum of the midbrain at the level of the posterior colliculus. The axons of cells located in this nucleus make up the nerve roots that pass through the central gray matter of the midbrain and the anterior cerebral velum, where, unlike other cranial nerves of the brainstem, they make a partial decussation, and then exit the upper surface of the brainstem near the frenulum of the anterior cerebral velum. sail. Having rounded the lateral surface of the brain stem, the trochlear nerve passes to the base of the skull; here it enters the outer wall of the cavernous sinus, and then through the superior orbital fissure enters the orbital cavity and reaches the eye muscle innervated by it. Since the IV cranial nerve in the anterior medullary velum makes a partial decussation, there are no alternating syndromes involving this nerve. Unilateral damage to the trunk of the IV cranial nerve leads to paralysis or paresis of the superior oblique muscle of the eye, manifested by strabismus and diplopia, especially significant when turning the gaze down and inward, for example, when descending stairs. With damage to the IV cranial nerve, a slight tilt of the head to the side opposite to the affected eye is also characteristic (compensatory posture due to diplopia).
11.2.2. Oculomotor (III) nerve (n. oculomotorius)
oculomotor nerve, n. oculomotorius(III cranial nerve) is mixed. It consists of motor and autonomic (parasympathetic) structures. In the tegmentum of the midbrain at the level of the superior colliculus, a group of heterogeneous nuclei is represented (Fig. 11.2). Motor paired large cell nuclei, which provide innervation to most of the external striated muscles of the eye, occupy a lateral position. They consist of cell groups, each of which is related to the innervation of a particular muscle. In front of these nuclei is a group of cells whose axons provide innervation to the muscle that lifts the upper eyelid.
Rice. 11.2.The location of the nuclei of the oculomotor (III) nerve [According to L.O. Darkshevich]. 1 - the core for the muscle that lifts the upper eyelid (m. levator palpebrae); 2 - core for the upper rectus muscle (m. rectus superior); 3 - core for the lower rectus muscle (m. rectus inferior); 4 - core for the lower oblique muscle (m. obliquus inferior); 5 - core for the medial rectus muscle of the eye (m. rectus medialis); 6 - the core for the muscle that narrows the pupil (m. sphincter pupillae, Yakubovich-Edinger-Westphal kernel); 7 - accommodation core (Perlia core).
(m. levator palpebrae superioris), followed by cell groups for the muscles that turn the eyeball up (m. rectus superior), up and out (m. obliquus inferior), inside (m. rectus medialis) and down (m. rectus inferior).
Medial to the paired large-cell nuclei are paired small-cell parasympathetic nuclei of Yakubovich-Edinger-Westphal. Impulses coming from here pass through the ciliary vegetative node (ganglion ciliare) and reach two smooth muscles - the internal muscles of the eye - the muscle that narrows the pupil, and the ciliary muscle (m. sphincter pupillae et m. ciliaris). The first of them provides constriction of the pupil, the second - the accommodation of the lens. In the midline between the nuclei of Yakubovich-Edinger-Westphal, there is an unpaired nucleus of Perlia, which, apparently, is related to the convergence of the eyeballs.
The defeat of individual cell groups related to the system of nuclei of the III cranial nerve leads to a violation of only those functions that they have a direct effect on. In this regard, with damage to the midbrain tegmentum, the function of the III cranial nerve may be partial.
The axons of the cells of the nuclei of the oculomotor nerve go down, while those that start from the cells laid down in the caudal cell groups of the lateral large cell nucleus partially pass to the other side. Thus formed, the third cranial nerve root crosses the red nucleus and leaves the midbrain, leaving the base of the skull from the medial sulcus of the brain stem at the edge of the posterior perforated substance. In the future, the trunk of the III cranial nerve goes forward and outward and enters the upper, and then moves into the outer wall of the cavernous sinus, where it is located next to the IV and VI cranial nerves and with the first branch of the V cranial nerve. Coming out of the wall of the sinus, the III nerve again, together with the IV and VI nerves and with the first branch of the V nerve through the superior orbital fissure, enters the cavity of the orbit, where it divides into branches leading to the indicated external striated muscles of the eye, and the parasympathetic portion of the III nerve ends in the ciliary node, from which they depart to the internal smooth muscles of the eye (m. sphincter pupillae et m. ciliaris) parasympathetic postganglionic fibers. If damage to the nuclear apparatus of the III cranial nerve can manifest itself as a selective disorder of the functions of individual muscles innervated by it, then pathological changes in the trunk of this nerve usually lead to a breakdown in the functions of all muscles, the innervation of which it
Rice. 11.3.Muscles that provide movement of the eyeballs, and their innervation (III, IV, VI cranial nerves). The directions of displacement of the eyeballs during the contraction of these muscles. R. ext. - external rectus muscle (it is innervated by the VI cranial nerve); O. inf. - inferior oblique muscle (III nerve); R. sup. - superior rectus muscle (III nerve); R. med. - medial rectus muscle (III nerve); R. inf. - lower rectus muscle (III nerve); O. sup. (III nerve) - superior oblique muscle (IV nerve).
should provide. Concomitant neurological disorders depend on the level of damage to the III cranial nerve and on the nature of the pathological process (Fig. 11.3).
Damage to the oculomotor nerve can cause drooping (ptosis) of the upper eyelid and divergent strabismus, which occurs due to the predominant influence on the position of the eyeball innervated by the VI cranial nerve of the rectus extrinsic muscle of the eye (Fig. 11.4). There is double vision (diplopia), there are no or sharply limited movements of the eyeball in all directions, except for the outer one. No convergence
Rice. 11.4.Damage to the right oculomotor (III) nerve:
a - ptosis of the upper eyelid; b - divergent strabismus and anisocoria detected with passive lifting of the upper eyelid.
eyeball (noted normally when approaching the bridge of the nose moving in the sagittal plane of the object). Due to paralysis of the muscle that constricts the pupil, it is dilated and does not respond to light, while both the direct and friendly reaction of the pupil to light is disturbed (see chapters 13, 30).
11.3. MEDIAL LONGITUDINAL BEAM AND SIGNS OF ITS DEFEAT
Medial (posterior) longitudinal bundle (fasciculis longitudinalis medialis)- a paired formation, complex in composition and function, starting from the nucleus of Darkshevich and the intermediate nucleus of Cajal at the level of the metathalamus. The medial longitudinal bundle passes through the entire brainstem near the midline, ventral to the central periaqueductal gray matter, and under the floor of the IV ventricle of the brain penetrates into the anterior cords of the spinal cord, ending at the cells of its anterior horns at the cervical level. It is a collection of nerve fibers belonging to various systems. It consists of descending and ascending pathways that connect paired cellular formations of the brain stem, in particular, nuclei III, IV and VI of the cranial nerves that innervate the muscles that provide eye movements, as well as the vestibular nuclei and cellular structures that make up the reticular formation, and anterior horns of the cervical spinal cord.
Due to the associative function of the medial longitudinal fasciculus, normal movements of the eyeballs are always friendly, combined. Involvement in the pathological process of the medial longitudinal bundle leads to the emergence of various oculovestibular disorders, the nature of which depends on the localization and prevalence of the pathological focus. The defeat of the medial longitudinal beam can cause various forms of gaze disorder, strabismus and nystagmus. Damage to the medial bundle often occurs in severe traumatic brain injury, in violation of blood circulation in the brainstem, with its ea8 compression as a result of wedging of the structures of the mediobasal parts of the temporal lobe into Bisha's fissure (the gap between the edge of the notch of the cerebellum and the brain stem), with compression of the brainstem a tumor of subtentorial localization, etc. (Fig. 11.5).
With damage to the medial longitudinal beam, the following syndromes are possible.
Gaze paresis- a consequence of a dysfunction of the medial bundle - the impossibility or limitation of friendly rotation of the eyeballs in one direction or another horizontally or vertically.
To assess the mobility of the patient's gaze, they are asked to follow an object moving horizontally and vertically. Normally, when turning the eyeballs to the sides, the lateral and medial edges of the cornea should touch the outer and inner commissures of the eyelids, respectively, or approach them at a distance of no more than 1-2 mm. Turning the eyeballs down is normally possible by 45?, up - by 45-20? depending on the age of the patient.
Paresis of gaze in the vertical plane - usually is a consequence of damage to the tegmentum of the midbrain and metathalamus at the level of the posterior commissure of the brain and the part of the medial longitudinal bundle located at this level.
Rice. 11.5.Innervation of the eye muscles and medial longitudinal bundles, providing their connections with each other and with other brain structures.
1 - the nucleus of the oculomotor nerve; 2 - accessory nucleus of the oculomotor nerve (nucleus of Yakubovich-Edinger-Westphal); 3 - posterior central nucleus of the oculomotor nerve (Perlia's nucleus), 4 - ciliary node; 5 - the nucleus of the trochlear nerve; 6 - the core of the abducens nerve; 7 - own nucleus of the medial longitudinal bundle (Darkshevich's nucleus); 8 - medial longitudinal bundle; 9 - adversive center of the premotor zone of the cerebral cortex; 10 - lateral vestibular nucleus.
Syndromes of lesions 1a and 1b - large cell nucleus of the oculomotor (III) nerve,
II - accessory nucleus of the oculomotor nerve; III - nuclei of the IV nerve; IV - nuclei of the VI nerve; V and VI - lesion of the right adversive field or the left pontine center of gaze Pathways providing friendly eye movements are marked in red.
Paresis of gaze in the horizontal plane develops when the pontine tire is damaged at the level of the nucleus of the VI cranial nerve, the so-called pontine gaze center (paresis of the gaze towards the pathological process).
Paresis of the gaze in the horizontal plane also occurs when the cortical center of the gaze, located in the posterior part of the middle frontal gyrus, is damaged. In this case, the eyeballs are turned towards the pathological focus (the patient "looks" at the focus). Irritation of the cortical center of gaze may be accompanied by a combined turn of the eyeballs in the direction opposite to the pathological focus (the patient "turns away" from the focus), as is sometimes the case, for example, during an epileptic seizure.
floating eyes symptom lies in the fact that in patients in a coma in the absence of paresis of the eye muscles due to dysfunction of the medial tufts, the eyes spontaneously make floating movements. They are slow in pace, non-rhythmic, chaotic, can be both friendly and asynchronous, appear more often in the horizontal direction, however, individual movements of the eyes in the vertical direction and diagonally are also possible. With floating movements of the eyeballs, the oculocephalic reflex is usually preserved. These eye movements are the result of gaze disorganization and cannot be reproduced arbitrarily, always indicating the presence of a pronounced organic brain pathology. With severe inhibition of stem functions, floating eye movements disappear.
Hertwig-Magendie sign - a special form of acquired strabismus, in which the eyeball on the side of the lesion is turned downward and inwards, and the other - upward and outward. This dissociated position of the eyes persists even with changes in the position of the gaze. The symptom is caused by a lesion of the medial longitudinal bundle in the midbrain tegmentum. It often occurs as a result of circulatory disorders in the brain stem, it is possible with a tumor of subtentorial localization or traumatic brain injury. Described in 1826 by the German physiologist K.H. Hertwig (1798-1887) and in 1839 the French physiologist F. Magendie (1783-1855).
Internuclear ophthalmoplegia - a consequence of unilateral damage to the medial longitudinal bundle in the tegmentum of the brain stem in the area between the middle part of the bridge and the nuclei of the oculomotor nerve and the resulting deefferentation of these nuclei. Leads to impaired gaze (friendly movements of the eyeballs) due to a disorder of the innervation of the ipsilateral internal (medial) rectus muscle of the eye. As a result, paralysis of this muscle occurs and the inability to turn the eyeball in the medial direction beyond the midline, or moderate (subclinical) paresis, leading to a decrease in the speed of adduction of the eye (to its adductive delay), while on the opposite side of the affected medial longitudinal fascicle, monocular abduction nystagmus. The convergence of the eyeballs is preserved. With unilateral internuclear ophthalmoplegia, the divergence of the eyeballs in the vertical plane is possible, in such cases the eye is located higher on the side of the lesion of the medial longitudinal fasciculus. Bilateral internuclear ophthalmoplegia is characterized by paresis of the adductor eyeball muscle on both sides, a violation of friendly eye movements in the vertical plane and gaze turns when checking the oculocephalic reflex. Damage to the medial longitudinal fasciculus in the anterior part of the midbrain can also lead to a violation of the convergence of the eyeballs. The reason for the internuclear
ophthalmoplegia can be multiple sclerosis, circulatory disorders in the brain stem, metabolic intoxication (in particular, with paraneoplastic syndrome), etc.
Lutz syndrome- a variant of internuclear ophthalmoplegia, characterized by supranuclear paralysis of abduction, in which voluntary movements of the eye outward are disturbed, however, reflexively, with caloric stimulation of the vestibular apparatus, its complete abduction is possible. Described by the French doctor H. Lutz.
One and a half syndrome - a combination of bridging gaze paresis in one direction and manifestations of internuclear ophthalmoplegia when looking in the other direction. The anatomical basis of the one-and-a-half syndrome is a combined lesion of the ipsilateral medial longitudinal fasciculus and the pontine center of gaze or the pontine paramedian reticular formation. The clinical picture is based on impaired eye movements in the horizontal plane with preserved vertical excursion and convergence. The only possible movement in the horizontal plane is the abduction of the eye opposite to the pathological focus, with the occurrence of its mononuclear abduction nystagmus with the complete immobility of the eye, ipsilateral to the pathological focus. The name "one and a half" has the following origin: if the usual friendly movement in one direction is taken as 1 point, then the gaze movements in both directions are 2 points. With one and a half syndrome, the patient retains the ability to avert only one eye, which corresponds to 0.5 points from the normal range of eye movements in the horizontal plane. Therefore, 1.5 points are lost. Described in 1967 by the American neurologist C. Fisher.
Oculocephalic reflex (doll head and eye phenomenon, doll eye test, Cantelli symptom) - reflex deviation of the eyeballs in the opposite direction when the patient's head turns in the horizontal and vertical planes, which are carried out by the examiner first slowly and then quickly (do not check if damage to the cervical spine is suspected!). After each turn, the patient's head should be held in the extreme position for a while. These gaze movements are carried out with the participation of stem mechanisms, and the sources of impulses going to them are the labyrinth, vestibular nuclei and cervical proprioceptors. In patients in a coma, the test is considered positive if the eyes, when checking it, move in the direction opposite to the turn of the head, maintaining their position in relation to external objects. A negative test (lack of eye movements or eye movements) indicates damage to the pons or midbrain or barbiturate poisoning. Normally, reflex gaze movements when checking the oculocephalic reflex in an awake person are suppressed. With intact consciousness or its slight suppression, the vestibular reflex, which causes the phenomenon, is completely or partially suppressed, and the integrity of the structures responsible for its development is checked by inviting the patient to fix his gaze on a certain object, while passively turning his head. In the case of a drowsy state of the patient in the process of checking the oculocephalic reflex, during the first two or three turns of the head, friendly turns of the gaze in the opposite direction occur, but then disappear, since the test leads to the awakening of the patient. Described Cantelli's disease.
convergent nystagmus. It is characterized by spontaneous slow divergent movements of the drift type, interrupted by fast convergent shocks. Occurs when the midbrain tegmentum and its connections are damaged, may alternate with retraction nystagmus. Described in 1979 by Ochs et al.
Vestibulo-ocular reflex - reflex coordinated movements of the eyeballs, ensuring the retention of the fixation point in the zone of best vision in cases of changes in head position, as well as changes in gravity and acceleration. They are carried out with the participation of the vestibular system and cranial nerves that innervate the muscles that provide gaze movements.
11.4. CENTRAL SYMPATHY PATH
The central sympathetic pathway presumably originates in the nuclei of the posterior hypothalamus and in the reticular formation of the anterior brainstem. At the level of the midbrain and pons, it passes under the aqueduct of the brain and under the lateral parts of the floor of the IV ventricle of the brain near the spinothalamic pathway. The autonomic sympathetic fibers that make up the central sympathetic pathway end at the sympathetic cells of the lateral horns of the spinal cord, in particular, at the cells of the ciliospinal sympathetic center. The defeat of the central sympathetic pathway and the specified center, located in the segments of the spinal cord C VIII -Th I, is manifested primarily by Horner's syndrome (Claude Bernard-Horner) (see Chapter 13).
11.5. SOME SYNDROMES OF DAMAGE TO THE MIDDLE BRAIN AND ITS CRANIAL NERVES
Quadruple syndrome. When the midbrain is damaged on both sides, there is a violation of the upward rotation of the gaze, combined with a weakening or absence of a direct and friendly reaction to light on both sides and with a violation of the convergence of the eyeballs.
With the localization of the pathological focus in one half of the midbrain, the following syndromes may occur.
Knapp syndrome- dilation of the pupil (paralytic mydriasis) on the side of the pathological process in combination with central hemiparesis on the opposite side, manifests itself with damage to the autonomic portion of the III cranial nerve or the parasympathetic nucleus of the midbrain, as well as the pyramidal tract, in particular, in the syndrome of herniation of the mediobasal regions temporal lobe into Bish's fissure (see chapter 21). Refers to alternating syndromes. Described by the German ophthalmologist H.J. Knapp (1832-1911).
Weber Syndrome (Weber-Gübler-Gendre Syndrome) - an alternating syndrome that occurs when the base of the brain stem is damaged in the area where it is crossed by the root of the oculomotor nerve. Manifested on the affected side by paresis or paralysis of the external and internal muscles of the eye (ptosis of the upper eyelid, ophthalmoparesis or ophthalmoplegia, mydriasis); on the opposite side, central hemiparesis is noted (Fig. 11.6). It often occurs in connection with a violation of blood circulation in the oral part of the brain stem. Opi-
Rice. 11.6.Schematic representation of the development of alternating syndromes of Weber (a) and Benedict (b).
1 - nuclei of the oculomotor nerve;
2 - medial longitudinal bundle;
3 - black substance; 4 - occipital-temporal-parietal tract; 5, 6 - frontal-bridge tract; 7 - red core, 8 - medial longitudinal bundle. The lesions are shaded.
Sali English physician H. Weber (1823-1918) and French physicians A. Gubler (1821-1879) and A. Gendrin (1796-1890).
Benedict syndrome - alternating syndrome in the localization of the pathological focus in the tegmentum of the midbrain, at the level of the nuclei of the oculomotor nerve, the red nucleus and the cerebellar-red nuclear connections. It manifests itself on the side of the lesion by pupil dilation in combination with paralysis of the striated muscles innervated by the oculomotor nerve, and on the opposite side by intentional trembling, sometimes hyperkinesia of the choreoathetosis type and hemihypesthesia. Described in 1889 by the Austrian neurologist M. Benedikt (1835-1920).
Upper red nucleus syndrome (Foy's syndrome) occurs if the pathological focus is located in the tegmentum of the midbrain in the area of the upper part of the red nucleus, and manifests itself on the opposite side with cerebellar hemitremor (intentional trembling), which can be combined with hemiataxia and choreoathetosis. The oculomotor nerves are not involved in the process. Described by the French neurologist Ch. Foix (1882-1927).
Lower red nucleus syndrome (Claude's syndrome) - an alternating syndrome caused by a lesion of the lower part of the red nucleus, through which the root of the III cranial nerve passes. On the side of the pathological process, there are signs of damage to the oculomotor nerve (ptosis of the upper eyelid, dilated pupil, divergent strabismus), and on the opposite
side cerebellar disorders (intentional trembling, hemiataxia, muscle hypotension). Described in 1912 by the French neurologist N. Claude (1869-1946).
Notnagel syndrome - a combination of signs of damage to the nuclear apparatus of the oculomotor nerve with hearing loss and cerebellar ataxia, which can be observed on both sides and at the same time be unevenly expressed. It occurs when the roof and tegmentum of the midbrain are damaged or compressed, as well as the upper cerebellar peduncles and structures of the metathalamus, primarily the internal geniculate bodies. It is more often manifested in tumors of the anterior trunk or pineal gland. Described in 1879 by the Austrian neurologist K. Nothnagel (1841-1905).
Cerebral aqueduct syndrome (Korber-Salus-Elschnig syndrome) - eyelid retraction and trembling, anisocoria, convergence spasm, vertical gaze paresis, nystagmus - a manifestation of damage to the gray matter surrounding the cerebral aqueduct, signs of occlusive hydrocephalus. Described by the German ophthalmologist R. Koerber and the Austrian ophthalmologists R. Salus (born in 1877) and A. Elschnig (1863-1939).
11.6. SYNDROMES OF DAMAGE TO THE BRAIN STEM AND CRANIAL NERVES AT DIFFERENT LEVELS
Oculofacial Congenital Paralysis (Mobius Syndrome) - Agnesia (aplasia) or atrophy of the motor nuclei, underdevelopment of roots and trunks III, VI, VII, less often - V, XI and XII cranial nerves, and sometimes the muscles innervated by them. It is characterized by lagophthalmos, manifestations of Bell's symptom, congenital, persistent, bilateral (rarely unilateral) paralysis or paresis of facial muscles, which is manifested, in particular, by difficulty in sucking, inexpressiveness or lack of facial reactions, lowered corners of the mouth, from which saliva flows. In addition, various forms of strabismus, drooping of the lower jaw, atrophy and immobility of the tongue are possible, which leads to impaired food intake, and in the future - articulation, etc. It can be combined with other malformations (microophthalmia, underdevelopment of the cochleovestibular system, hypoplasia of the lower jaw, aplasia of the pectoralis major muscle, syndactyly, clubfoot), oligophrenia. There are both hereditary and sporadic cases. The etiology is unknown. Described in 1888-1892. German neuropathologist P. Moebius (1853-1907).
Paralytic strabismus - strabismus that occurs with acquired paralysis or paresis of the muscles that provide movement of the eyeballs (a consequence of damage to the III, IV or VI cranial nerve system), usually combined with double vision (diplopia).
Non-paralytic strabismus - congenital strabismus (strabismus). It is characterized by the absence of diplopia, since in such cases the perception of one of the images is compensatory suppressed. Reduced vision in the non-imaging eye is called amblyopia without anopia.
Synkinesia Hun (by Markus Hun) - a type of pathological synkinesis with some lesions of the brain stem, accompanied by ptosis. Due to the preservation of embryonic connections between the motor nuclei of the trigeminal and oculomotor nerves, combined movements of the eyes and lower
her jaw., while involuntary lifting of the lowered eyelid when opening the mouth or when chewing is characteristic. Described by an English ophthalmologist
R.M. Gunn (1850-1909).
Superior orbital fissure syndrome (sphenoidal fissure syndrome) - combined violation of the functions of the oculomotor, block, abductor, and ophthalmic branch trigeminal nerves passing from the cavity of the middle cranial fossa into the orbit through the superior orbital (sphenoidal) fissure, characterized by ptosis of the upper eyelid, diplopia, ophthalmoparesis or ophthalmoplegia in combination with signs of irritation (trigeminal pain) or decreased function (hypalgesia) of the optic nerve . Depending on the nature of the underlying process, there may be various accompanying manifestations: exophthalmos, hyperemia, swelling in the orbit, etc. It is a possible sign of a tumor or inflammatory process in the area of the medial part of the lesser wing of the sphenoid bone.
Orbital apex syndrome (Rollet's syndrome) - a combination of signs of the syndrome of the superior orbital fissure and damage to the optic nerve, as well as exophthalmos, vasomotor and trophic disorders in the orbit area. Described by the French neurologist J. Rollet (1824-1894).
Orbital floor syndrome (Dejan's syndrome) - manifested by ophthalmoplegia, diplopia, exophthalmos and hyperpathy in combination with pain in the area innervated by the ophthalmic and maxillary branches of the trigeminal nerve. This syndrome, which appears during pathological processes in the bottom of the orbit, was described by the French ophthalmologist Ch. Dejan (born in 1888).
Diabetic polyneuropathy of the cranial nerves - acutely or subacutely developing asymmetric reversible polyneuropathy of the cranial nerves (usually oculomotor, abducens, facial, trigeminal), sometimes occurring in patients with diabetes mellitus.
Koller syndrome (Kolle) - ophthalmoplegia in combination with pain in the area innervated by the optic nerve (the first branch of the trigeminal nerve) with periostitis in the region of the superior orbital fissure. It can develop after hypothermia and during the transition of the inflammatory process from the paranasal sinuses. It is characterized by relative short duration and reversibility. Described in 1921 by the American neurologist J. Collier (1870-1935).
Painful ophthalmoplegia syndrome (Tholosa-Hunt syndrome, steroid-sensitive ophthalmoplegia) - non-purulent inflammation (pachymeningitis) of the outer wall of the cavernous sinus, the superior orbital fissure or the apex of the orbit. The inflammatory process involves all or some of the cranial nerves that provide movement of the eyeballs (III, IV and VI nerves), the ophthalmic, less often the maxillary branch of the trigeminal nerve and the sympathetic plexus of the internal carotid artery due to its periarteritis, and sometimes the optic nerve. It manifests itself as a sharp constant "drilling" or "gnawing" pain in the orbital, retroorbital and frontal areas in combination with ophthalmoparesis or ophthalmoplegia, vision loss, Horner's syndrome, sometimes moderate exophthalmos, signs of venous congestion in the fundus are possible. Painful ophthalmoplegia syndrome persists for several days or several weeks, after which spontaneous remission usually occurs, sometimes with residual neurological deficit. After remission from several weeks to many years, there may be a recurrence of pain ophthalmoplegia syndrome. Outside the zone of the cavernous sinus, there are no morphological changes, there are no grounds for diagnosing systemic pathology. The infectious-allergic nature of the process is recognized. Characterized by a positive reaction
for corticosteroid treatment. Currently, it is considered as an autoimmune disease with clinical and morphological polymorphism, while the manifestation of benign granulomatosis in the structures of the skull base is characteristic. Similar clinical manifestations are possible with aneurysm of the vessels of the base of the skull, parasellar tumor, basal meningitis. Described in 1954 by the French neurologist F.J. Tolosa (1865-1947) and in more detail - in 1961 the American neurologist W.E. Hunt (1874-1937) et al.
Cavernous sinus lateral wall syndrome (Foy's syndrome) - paresis of the external rectus muscle, and then other external and internal muscles of the eye on the side of the pathological process, which leads to ophthalmoparesis or ophthalmoplegia and a disorder of pupillary reactions, while exophthalmos, pronounced swelling of the tissues of the eyeball due to venous stasis are possible. The causes of the syndrome may be thrombosis of the cavernous sinus, the development of an aneurysm of the carotid artery in it. Described in 1922 by the French doctor Ch. Foix (1882-1927).
Jefferson syndrome - aneurysm of the internal carotid artery in the anterior part of the cavernous sinus, manifested by a pulsating noise in the head in combination with signs characteristic of the cavernous sinus syndrome. Characterized by pain and swelling of the tissues of the fronto-orbital region, chymosis, ophthalmoplegia, mydriasis, pulsating exophthalmos, hypalgesia in the area of the optic nerve. In advanced cases, expansion and deformation of the superior orbital fissure and atrophy of the anterior sphenoid process detected on craniograms are possible. The diagnosis is confirmed by carotid angiography data. Described in 1937 by the English neurosurgeon G. Jefferson.
Syndrome of the supraorbital fissure (sphenoidal fissure syndrome, retrosphenoidal space syndrome, Jacot-Negri syndrome) - a combination of signs of damage to the optic, oculomotor, trochlear, trigeminal and abducens nerves on one side. It is observed in tumors of the nasopharynx, growing into the middle cranial fossa and cavernous sinus, manifested by the Jacot triad. Described by the modern French physician M. Jacod and the Italian pathologist A. Negri (1876-1912).
Triad Jaco.On the side of the lesion, blindness, ophthalmoplegia are noted, and due to the involvement of the trigeminal nerve in the process, intense constant, sometimes intensifying pain in the area innervated by it, as well as peripheral paresis of the masticatory muscles. Occurs with retrosphenoidal space syndrome. Described by the modern French doctor M. Jacco.
Glicka syndrome- alternating syndrome associated with damage to several levels of the brain stem. It is characterized by a combined lesion of the II, V, VII, X cranial nerves and the cortical-spinal tract. Manifested on the side of the pathological process by decreased vision or blindness, peripheral paresis of facial muscles, pain in the supraorbital region and difficulty swallowing, on the opposite side - spastic hemiparesis. Described by the domestic doctor V.G. Glicks (1847-1887).
Garcin's syndrome (hemicranial polyneuropathy) - damage to all or almost all cranial nerves on one side without signs of damage to the substance of the brain, changes in the composition of the cerebrospinal fluid and manifestations of the syndrome of intracranial hypertension. It usually occurs in connection with an extradural malignant neoplasm of craniobasal localization. More often it is a sarcoma of the base of the skull, emanating from the nasopharynx, sphenoid bone or pyramid of the temporal bone. Destruction of the bones of the base of the skull is characteristic. Described in 1927 by the French doctor R. Garsin (1875-1971).
The extrapyramidal system is represented by multilink descending pathways, through which the regulation of involuntary movements, automatic motor acts, muscle tone, as well as movements that express emotions (smile, laugh, cry, etc.) is carried out.
The neurons of the inner pyramidal layer of the frontal cortex (field 6) (I neuron) send cortical striatal fibers to a new part of the striatum represented by the caudate nucleus and putamen. Here, the second neuron of the extrapyramidal pathways is localized, the processes of which go to the ancient part of the striatum - the pale ball (striato-pallidar fibers). The nerve cells of the globus pallidus are the III neuron, their axons go as part of a lenticular loop (Ansa lenticularis) to various nuclei of the brain stem - the subthalamic nucleus, the substantia nigra, the nuclei of the superior hillocks, the red nucleus, the lateral vestibular nucleus, the olive nucleus, the reticular nuclei. In these nuclei, an IV neuron is laid, which gives rise to descending pathways that transmit signals to the motor nuclei of the cranial nerves and spinal cord: tectospinal (tractus tectospinalis), red nuclear-spinal(tractus rubrospinalis), vestibulospinal(tractus vestibulospinalis), olivo-spinal(tractus olivospinalis), reticular-spinal(fasciculi reticulospinalis). The motor cells of the nuclei of the cranial nerves and the anterior horns of the spinal cord form the V neuron of the extrapyramidal pathways, which sends impulses to the skeletal muscles.
The red nucleus is the main motor coordination center of the extrapyramidal system. It has numerous connections with the cerebral cortex, with the striopallidar system, with the thalamus, with the subthalamic region and with the cerebellum. From the structures of the diencephalon, neurons of the medial nuclei of the thalamus (subcortical sensory center of the extrapyramidal system), neurons of the pale ball (pallidar system) and neurons of the posterior nuclei of the hypothalamus are connected with the red nucleus. The axons of the cells of the nuclei of the diencephalon are collected in the thalamo-red nuclear bundle, fasciculus thalamorubralis, which ends on the cells of the red nucleus and the black substance. Neurons of the black matter also have connections with the red nucleus. Nerve impulses coming to the neurons of the red nucleus from the cerebellum carry out the so-called "corrective" activity. They ensure the performance of fine targeted movements and prevent inertial manifestations during movements.
Red nuclear-spinal tract (tractus rubrospinalis)(Monakov's bundle), ensures the performance of complex habitual movements (walking, running), contributes to the long-term maintenance of the body posture, as well as the tone of the skeletal muscles. It starts from large multipolar neurons of the red nucleus. The axons of these neurons immediately pass to the opposite side in the midbrain tegmentum and form a ventral decussation of the tegmentum. (decussatio tegmenti ventralis)(Forel cross). Further, the red nuclear-spinal tract descends into the lateral funiculus of the spinal cord, where it is located anterior to the lateral cortical-spinal tract. The axons end in segments on the motoneurons of the motor nuclei of the anterior horns of the spinal cord of their side. Axons of motor neurons leave the spinal cord as part of the anterior roots of the spinal nerves, and then, as part of the nerves themselves and their branches, are sent to the skeletal muscles.
Covering-spinal tract (tractus tectospinalis) performs unconditioned reflex motor reactions in response to sudden strong visual, auditory, tactile and olfactory stimuli. The path begins on the neurons of the upper colliculus of the midbrain, where information comes from the subcortical centers of vision and hearing (the nuclei of the upper and lower colliculi), from the subcortical center of smell, along the collaterals of the exteroceptive tracts. Axons of neurons go up, bypass the central gray matter of the midbrain and go to the opposite side. The intersection of the fibers of the tectospinal tract with the tract of the same name on the opposite side is called the dorsal decussation of the tegmentum. (decussatio tegmenti dorsalis), or fountain-shaped decussation (Meinert) - according to the nature of the course of nerve fibers. Further, the tract passes in the dorsal part of the bridge next to the medial longitudinal bundle. In the brainstem, part of the fibers ends on the motor neurons of the motor nuclei of the cranial nerves. (fasciculus tectonuclearis). They provide protective reactions involving the muscles of the head and neck. In the area of the medulla oblongata, the tectospinal tract approaches the dorsal surface of the pyramids and goes to the anterior funiculus of the spinal cord. In the spinal cord, it occupies the most medial part of the anterior funiculus, limiting the anterior median fissure. The tectospinal tract can be traced throughout the entire spinal cord. Gradually thinning, it gradually gives off branches to small alpha motor neurons of the motor nuclei of the anterior horns of the spinal cord of its side. Axons of motor neurons conduct nerve impulses to the muscles of the trunk and limbs. When the occlusal-spinal tract is damaged, starting reflexes, reflexes to sudden sound, auditory, olfactory and tactile irritations disappear.
Reticular-spinal tract (tractus reticulospinalis) designed to perform complex reflex acts (breathing, grasping movements, etc.), requiring the simultaneous participation of many groups of skeletal muscles. The reticular-spinal tract conducts nerve impulses that have an activating or, conversely, inhibitory effect on the motor neurons of the motor nuclei of the anterior horns of the spinal cord. In addition, this pathway transmits impulses to gamma motor neurons that provide skeletal muscle tone. The axons of neurons located in the reticular formation of the brain stem go in a downward direction. In the spinal cord, they form a bundle, which is located in the anterior funiculus. The bundle is well expressed only in the cervical and upper thoracic regions of the spinal cord. Segmentally, it becomes thinner, giving fibers to the gamma motor neurons of the motor nuclei of the anterior horns of the spinal cord. The axons of these neurons travel to the skeletal muscles.
Vestibulo-spinal tract (tractus vestibulospinalis) provides unconditioned reflex motor acts in violation of the balance of the body. The vestibulospinal tract is formed by the axons of the cells of the lateral and inferior vestibular nuclei (the nuclei of Deiters and Roller). In the medulla oblongata, it is located in the dorsal region. In the spinal cord, it passes at the border of the lateral and anterior cords, therefore it is penetrated by horizontally oriented fibers of the anterior roots of the spinal nerves. The fibers of the vestibulo-spinal tract end in segments on the alpha motor neurons of the motor nuclei of the anterior horns of the spinal cord. Axons of motor neurons in the composition of the anterior roots of the spinal nerves leave the spinal cord and go to the skeletal muscles.
Olivo-spinal tract (tractus olivospinalis) provides unconditioned reflex maintenance of the tone of the neck muscles and motor acts aimed at maintaining the balance of the body. The olivo-spinal tract starts from the neurons of the inferior olive nucleus of the medulla oblongata. Being a phylogenetically new formation, the lower olive nucleus has direct connections with the cortex of the hemispheres of the frontal lobe (cortical-olive pathway, tractus corticoolivaris) and with the cerebellar cortex (olivocerebellar pathway, tractus olivocerebellaris). The olivo-spinal tract passes through the anteromedial portion of the lateral funiculus and can be traced only at the level of the six upper cervical segments of the spinal cord. The fibers of the olivo-spinal tract terminate in segments on the alpha motor neurons of the motor nuclei of the anterior horns of the spinal cord. Axons of motor neurons as part of the roots of the spinal nerves leave the spinal cord and go to the muscles of the neck.
Medial longitudinal bundle (fasciculus longitudinalis medialis) is a combination of descending and ascending fibers that carry out combined movements of the eyeballs and head. The bundle is formed by the axons of the neurons of the intermediate nucleus ( nucleus interstitialis)(nucleus of Cajal), and nuclei of the posterior commissure (nucleus commissurae posterioris)(Kernel of Darkshevich). The medial longitudinal bundle passes under the central gray matter near the midline, then it continues in the dorsal part of the bridge and deviates ventrally in the medulla oblongata. In the spinal cord, it is located in the anterior funiculus, in the angle between the medial surface of the anterior horn and the anterior white commissure. The medial longitudinal fasciculus is traced only at the level of the upper six cervical segments. Within the midbrain, fibers from the posterior longitudinal bundle (Schutz), which unites the autonomic centers, enter the medial longitudinal bundle. This connection between the medial and posterior longitudinal bundles explains the emerging autonomic reactions during vestibular loads. From the medial longitudinal bundle, fibers are directed to the motor nucleus of the oculomotor nerve. Further, within the midbrain, from the composition of the medial longitudinal bundle, fibers are sent to the neurons of the motor nucleus of the trochlear nerve of the opposite side. This nucleus is responsible for the innervation of the superior oblique muscle of the eyeball. In the bridge, the axons of the Deiters nucleus (VIII pair - the vestibulocochlear nerve) also enter the medial longitudinal bundle, which go in an ascending direction to the neurons of the intermediate nucleus. Fibers depart from the medial longitudinal bundle to the neurons of the motor nucleus of the abducens nerve (VI pair), which is responsible for the innervation of the lateral rectus muscle of the eyeball. And, finally, within the medulla oblongata and spinal cord from the medial longitudinal bundle, the fibers are directed to the neurons of the motor nucleus of the accessory nerve (XI pair) and the motor nuclei of the anterior horns of the six upper cervical segments responsible for the work of the neck muscles.
In addition to the general coordination of the work of the muscles of the eyeball and the head, the medial longitudinal bundle plays an important integrative role in the activity of the muscles of the eye. By communicating with the cells of the nucleus of the oculomotor and abducens nerves, it ensures the coordinated function of the external and internal rectus muscles of the eye, which manifests itself in a combined turn of the eyes to the side. In this case, there is a simultaneous contraction of the external rectus muscle of one eye and the internal rectus muscle of the other eye. With damage to the intermediate nucleus or the medial longitudinal bundle, there is a violation of the coordinated work of the muscles of the eyeball. Often these disorders are supplemented by vestibular disorders (dizziness) and vegetative disorders (nausea, vomiting, etc.).
Posterior longitudinal beam (fasciculus longitudinalis dorsalis) is a combination of descending and ascending fibers that carry out connections between the autonomic centers of the brain stem and spinal cord. The posterior longitudinal bundle (Schütz's bundle) originates from the cells of the posterior nuclei of the hypothalamus. The axons of these cells unite into a bundle only at the border of the diencephalon and midbrain. Further, it passes in close proximity to the aqueduct of the midbrain. Already in the midbrain, part of the fibers of the posterior longitudinal bundle goes to the accessory nucleus of the oculomotor nerve. In the region of the bridge, fibers depart from it to the lacrimal and superior salivary nuclei of the facial nerve. In the medulla, fibers branch off to the inferior salivary nucleus of the glossopharyngeal nerve and the dorsal nucleus of the vagus nerve. In the spinal cord, the posterior longitudinal bundle is located in the form of a narrow ribbon in the lateral funiculus, next to the lateral cortical-spinal tract. The fibers of the Schutz bundle end in segments on the neurons of the lateral intermediate nucleus, which are the autonomic sympathetic centers of the spinal cord. Only a small part of the fibers of the dorsal longitudinal bundle separates at the level of the lumbar segments and is located near the central canal. This bundle is called the peri-ependymal (fasciculus paraependimalis). The fibers of this bundle end on the neurons of the sacral parasympathetic nuclei. The axons of the cells of the parasympathetic and sympathetic nuclei leave the brainstem or spinal cord as part of the cranial or spinal nerves and go to the internal organs, vessels and glands. Thus, the posterior longitudinal bundle plays a very important integrative role in the regulation of vital body functions.
The extrapyramidal pathways also include a system of fibers that connect the cerebral cortex with the cerebellum. The first neurons of the cortical-cerebellar pathway are located in the V layer of the cortex of the various lobes of the cortex of the cerebral hemispheres. Their axons end on the cells of their own nuclei of the bridge of their side. The set of axons of pyramidal neurons, heading to their own nuclei of the bridge, makes up the cortical-bridge path (tractus corticopontinus). There are two main tracts: frontal-pontine and occipital-temporal-pontine.
Lobno-bridge way(tractus frontopontinus) starts from the neurons of the cortex of the frontal lobe of the cerebral hemispheres. Participates in the formation of the radiant crown, then gathers into a bundle that passes through the anterior leg of the internal capsule. In the midbrain, it is located in the medial part of the base of the brain stem. The bridge ends on the neurons of the own nuclei of the bridge.
Occipital-temporal-bridge way (tractus occipitotemporopontinus) formed by the axons of the cells of the cortex of the occipital, temporal and parietal lobes of the cerebral hemispheres. In the form of a single compact bundle, it passes through the middle part of the posterior leg of the internal capsule, in the midbrain it is located in the lateral part of the base of the brain stem, in the substance of the bridge it connects to the fronto-bridge tract and synaptically ends on the own nuclei of the bridge.
The second neurons of the cortico-cerebellar pathway are the neurons of the own nuclei of the bridge (nuclei pontis). The axons of these cells go in a horizontal direction, go to the opposite side (I cross). On the opposite side of the bridge, they combine into one very large bundle, which makes up the middle cerebellar peduncle. This bundle is called the pontocerebellar tract. (tractus pontocerebellaris). It ends in the cerebellar cortex (new cerebellum). Pear-shaped cells of the cerebellar cortex are taken as the third neuron. The impulses sent by them enter the dentate nucleus (IV neuron). From here there is a transmission of impulses along the gear-red nuclear path (tractus dentatorubralis) through the superior cerebellar peduncles to the red nucleus (V neuron). II decussation occurs in the midbrain tegmentum (decussatio pedunculorum cerebellarium superiorum). From the red nucleus begins the red nuclear-spinal path (tractus rubrospinalis), which after the cross (decussatio ventralis tegmenti) goes to the nuclei of the anterior horns of the spinal cord and the motor nuclei of the cranial nerves (VI neuron). From here, as part of the spinal and cranial nerves, impulses enter the muscles.
Through the cortical-bridge and pontine-cerebellar pathways and the ascending efferent pathways of the cerebellum, a circular interaction is carried out between the cerebral cortex and the cerebellum, which is necessary for the regulation and coordination of various motor acts. The cerebellum receives from the cerebral cortex, as it were, copies of the commands sent along the pyramidal and extrapyramidal pathways, compares them with the signaling coming from the proprioceptors and the vestibular apparatus, and sends the processed information to the higher motor centers of the cortex.
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Introduction to human anatomy
Variants and anomalies in the development of the vertebrae.. knowledge of various forms of variability of the vertebrae is of great practical value.. splitting of the vertebrae as a result of non-fusion of their parts that develop from separate ossification points..
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The ureter is a tube for conducting urine 30-35 cm long. Its lumen is not the same everywhere (5-7 mm). Topographically, the ureter is divided into abdominal, pelvic and intraparietal parts. The first two hours
Bladder
The bladder is a reservoir for urine. Its shape and size depend on the filling. In newborns, the bladder is fusiform or pear-shaped, located above the entrance to the small pelvis, its
Anomalies in quantity and magnitude, or volume
1. Kidney agenesis (syn.: arenia) - the complete absence of a kidney. It can be one- or two-sided. In 93.1% of cases, the ureters are absent, in 42% - the bladder, in 10% - the urethra.
Position and orientation anomalies
1. Dystopia (ectopia) of the kidney (syn.: dystopic kidney) - an abnormal position of the kidney. There are several forms: A) Kidney dystopia cross (
Form anomalies
1. Lobular kidney (syn.: embryonic kidney) - preservation of the infantile lobulation of the kidney. The borders of the lobules are well defined. 2. Kidney fused - mo
Anomalies in the structure (differentiation) of the renal parenchyma
1. Kidney dysplasia is a group of the most common defects, characterized by impaired differentiation of nephrogenic tissue with persistence of embryonic structures. According to morphological
Anomalies in structure and shape
1. Hypoplasia of the ureter - segmental or total underdevelopment of the ureter. 2. Congenital strictures (stenosis and atresia) - arise due to
Anomalies of location and confluence
1. Retrocaval ureter - the location of the ureter, usually the right one, behind the inferior vena cava. 2. Retroileal ureter - the ureter is located
Malformations of the urethra
1. Agenesia (aplasia) of the urethra (syn.: urethraplasia) - the absence of the urethra, is rare and often combined with agenesis of the penis and bladder.
Sex organs
The reproductive organs, or genitalia, provide for the development and excretion of germ cells, fertilization, and in mammals, also protection and nutrition of the embryo in the mother's body. Male and female reproductive organs ra
Development of the sex organs
The sex organs develop from the mesoderm. A feature of their embryonic development is the presence of an indifferent stage, when the male and female genital organs are morphologically indistinguishable. Differential
Male reproductive organs
The testicle is a complex tubular gland, the parenchyma of which consists of convoluted and straight seminiferous tubules and the interstitium surrounding them. Sperm occurs in the convoluted tubules
Female reproductive organs
The ovary, like the testicles, is an organ for the formation of germ cells and the production of sex hormones; functionally, the ovary plays a leading role in the female reproductive system.
Anomalies in the development of the testicle
1. Agenesis (aplasia) of the testicles (syn.: testicular regression syndrome, familial anorchia) - the absence of testicles. May be associated with agenesis (aplasia) of the epididymis and vas deferens
Anomalies of the development of the prostate gland
1. Agenesia (aplasia) of the prostate gland - observed with agenesis and exstrophy of the bladder, sometimes combined with testicular agenesis and hypospadias. Occurs rarely. 2
Anomalies in the development of the penis
1. Afallia (agenesia, aplasia of the penis) is an extremely rare defect. In this case, the urethra opens into the rectum or the skin of the perineum. May be accompanied
Anomalies in the development of the uterus
1. Agenesia of the uterus - the complete absence of the uterus due to its failure to form, is rare. 2. Aplasia of the uterus - congenital absence of the uterus. The uterus usually has
Anomalies in the development of the vagina
1. Vaginal agenesis - the complete absence of the vagina due to its failure to form. Occurs rarely. 2. Aplasia of the vagina - congenital absence of the vagina, p
Anomalies in the development of the external female genital organs
1. Agenesia of the clitoris - the complete absence of the clitoris due to its failure to form. It is extremely rare. 2. Hypertrophy of the clitoris (syn.: cliteromegaly)
Intersex conditions
Hermaphroditism, or bisexuality, refers to violations of the development of the genital organs, when signs of both male and female are combined in their structure. The word "hermaphrodite" comes from the Greek mythol
Endocrine system
Endocrine glands, or endocrine glands, are specialized organs that produce and secrete biologically into the internal environment of the body. active substances, I am
Hypothalamus
The hypothalamus is the highest nervous center for the regulation of endocrine functions. It controls and integrates all visceral functions of the body and combines endocrine regulation mechanisms with nervous,
Pituitary
The pituitary gland is an oval or roller-shaped body located in the pituitary fossa of the Turkish saddle and connected to the hypothalamus through a funnel. About 20 biologically active
Thyroid
The thyroid gland is the largest of all purely endocrine glands. In its development, the thyroid gland is a derivative of the primary pharynx. The rudiment of the gland appears in the embryo at 3-4
Parathyroid glands
The superior and inferior parathyroid glands are paired organs adjacent to the thyroid gland. In embryogenesis, the buds of the glands are laid on the 6th week in the III and IV pharyngeal meshes.
adrenal glands
The adrenal gland is a paired organ located next to the kidney. The composition of the adrenal gland includes the cortex and medulla, which have a different origin and structure. bark over
Paraganglia
Chromaffin cells are widely distributed in the body outside the adrenal glands. They form clusters called paraganglia along the aorta and its major branches. Paraganglia are formed on the 2nd
Pancreas
The pancreas is an organ of mixed secretion, consisting of endocrine and exocrine parts. The exocrine portion is made up of glandular cells that produce digestive enzymes.
Organs of the immune system
The immune system combines organs and tissues that protect the body from genetically alien cells or substances that come from outside or are formed in the body. immune system organs
Bone marrow
The bone marrow is both an organ of hematopoiesis and the immune system. Red bone marrow is isolated, which in an adult is located in the cells of the spongy substance, which are flat and short.
Thymus
The thymus gland is the central organ of the immune system. In it, stem cells that come here from the bone marrow with the blood flow, after passing through a series of intermediate stages, turn into a T-lymphocyte
Anomalies in the development of the thymus gland
1. Alimphoplasia (syn.: aplasia of the thymus) - congenital absence of the thymus, usually combined with hypoplasia of the entire lymphoid tissue. 2. Hipop
Spleen
The spleen is the organ where lymphatic tissue connects to the circulatory system. The position of the spleen in this system is similar to the position of the lymph nodes in the lymphatic system.
Anomalies in the development of the spleen
1. Alienia (syn.: asplenia) - congenital absence of the spleen. It occurs, as a rule, together with other anomalies, especially heart defects and vascular system. If one
The lymph nodes
Lymph nodes are the most numerous organs of the immune system. They lie on the paths of the lymphatic vessels from the organs and tissues to the lymphatic ducts and trunks.
tonsils
Tonsils: lingual, pharyngeal, palatine and tubal - located in the region of the root of the tongue, pharynx and nasal part of the pharynx. They are diffuse accumulations of lymphoid tissue containing small r
Accumulations of lymphoid tissue
Lymphoid nodules of the appendix during the period of their maximum development (after birth and up to 16-17 years) are located in the mucous membrane and in the submucosa throughout
General Anatomy of the Central Nervous System
According to I.P. Pavlov, an organism is not the sum of individual parts or organs, but a living integral system that is in continuous relationship with the external environment. The body in its continuous struggle with men
Evolution of the nervous system
All living things are characterized by the ability to perceive changes in the external environment as irritations, conduct these irritations and respond to them with adaptive reactions. Indeed, p
Embryogenesis of the nervous system
The nervous system develops from the ectoderm. Already at the stage of gastrula along the midline of the body on the dorsal side of the germinal shield in front of the primary streak and the primary tubercle of Hensen from cells of e
Age and individual variability of the CNS
Brain growth after birth occurs intensively in the first years of life, and then slows down more and more, lagging behind the general growth of the body. As a result, the ratio of brain mass to body mass in the period of growth
The structure of the spinal cord
The spinal cord is located in the spinal canal and is incorrectly cylindrical shape the body length in men is about 45 cm, in women - an average of 41-42 cm. The mass of the spinal cord of an adult
Age features of the spinal cord
Age features of the spinal cord relate to both its topography and structure. In the 2nd half of the intrauterine period, the growth of the spinal cord lags behind the growth of the spinal column, and in the newborn
Blood supply to the spinal cord
The blood supply to the spinal cord, its membranes and roots is carried out by numerous vessels that depart at the level of the neck of the vertebral, thyroid and subclavian arteries, at the level of the thoracic and lumbar
Anomalies in the development of the spinal cord
Anomalies in the development of the spinal cord are based on disorders in the development of the ectoderm and mesoderm and in most cases are combined with anomalies of the spinal column, as well as the brain and skull.
medulla oblongata and pons
These parts of the brain share many features and retain a certain resemblance to the spinal cord. At the same time, they differ significantly from the spinal cord. These differences are as follows. When transition
Cerebellum
The cerebellum develops from rhombic lips, which are laid in the dorsolateral part of the neural tube at the border with the roof of the hindbrain. It consists of an unpaired worm and paired hemispheres. Cerebellum character
midbrain
The midbrain is subdivided into the roof and legs of the cerebrum. The roof of the midbrain has superior and inferior colliculi. Part of the fibers of the lateral (auditory) loop approaches the nuclei of the inferior colliculus, and in
diencephalon
The diencephalon anatomically and functionally is the link between the cerebral hemispheres and the lower levels of the CNS. It is divided into thalamic and hypothalamic regions.
Reticular formation
For the first time, the reticular formation was described in 1865 by the German scientist O. Deiters, who proposed this term as well. This term denoted and continues to denote areas of the brain in which the
Hemispheres of the brain
The telencephalon is divided by a longitudinal fissure into two hemispheres, connected to each other through a system of adhesions. Cerebral hemispheres - the most progressively developing in vertebrates
The cortex of the hemispheres
The cerebral cortex is the most differentiated and complex nervous structure. The highest forms of reflection of the external world, all types of conscious human activity are associated with the cortex.
Basal nuclei
The basal ganglia are collections of gray matter in the lower hemispheres. They are phylogenetically old formations. They are isolated as a stem part of the telencephalon. TO
White matter of the hemispheres
The fibers of the white matter of the hemispheres can be divided into three groups: associative, commissural and projection. Association fibers connect different parts of the cortex within the same
Developmental anomalies as a result of non-closure of the neural tube
The defects of this group are called dysraphia of the cranial region. They are based on a violation of the development of the ectodermal and mesodermal sheets, as a result of which such defects are often accompanied by impaired
Developmental anomalies due to impaired migration and differentiation of nerve cells
This group of malformations is the most numerous. Here are just a few of the most common or most important clinically. 1. Agiriya (syn.: l
The membranes of the spinal cord and brain
In anatomy, physiology and especially in the pathology of the central nervous system great importance belongs to the connective tissue membranes of the spinal cord and brain. Development of the meninges
Meninges of the spinal cord
There are three membranes of the spinal cord: hard, arachnoid and soft. The hard shell is a cylindrical bag closed from below, repeating the shape of a vertebrate
Shells of the brain
The brain also has three shells - hard, arachnoid and soft. The hard shell of the brain is a fibrous plate adjacent to the inner surface of the black
Pathways of the central nervous system. afferent pathways
"The main thing in the organization of the nervous system is the organization of its connections." This exact formulation of the famous neuromorphologist B.I. Lavrentiev reveals the significance of the pathways of the central nervous system.
Associative Paths
Associative nerve fibers (neurofibrae associationes) connect areas of gray matter within one half of the brain, various functional centers. Allocate to
Commissural paths
Commissural nerve fibers (neurofibrae commissurales) connect the gray matter of the right and left hemispheres, similar centers of the right and left halves of the brain in order to
Pathway of pain and temperature sensitivity
Receptors for pain and temperature sensitivity are embedded in the skin and subcutaneous base of the trunk, limbs, as well as those parts of the neck of the head that receive innervation from the spinal nerves. imp
Pathway of tactile sensation, touch and pressure
Receptors for tactile sensitivity are embedded in the skin and subcutaneous tissue of the trunk, limbs, as well as those parts of the neck and head that receive innervation from the spinal nerves. Impulses before
Conducting pathways of proprioceptive sensitivity of the cortical direction
Receptors are embedded in the subcutaneous tissue (exteroceptors), muscles, tendons, articular surfaces, ligaments, fascia, periosteum (proprioceptors). Pulses are transmitted through sensitive fibers sp
Conducting pathways of proprioceptive sensitivity of the cerebellar direction
It has long been believed that the cerebellum is one of the centers of coordination and synergy of movements, regulation of muscle tone, and maintenance of balance. Academician L.A. Orbeli came to the conclusion that "the cerebellum
Some regularities in the structure of afferent projection pathways
1. The beginning of each path is represented by receptors embedded in the skin, subcutaneous tissue or deep parts of the body. 2. The first neuron in all afferent pathways is located outside the central nervous system.
Afferent pathways of the cranial nerves
1. The afferent path of the trigeminal nerve starts from exteroceptors located in the skin and mucous membranes of the head (areas of innervation of the trigeminal nerve), and mi proprioceptors
pyramid path
The pyramidal pathway (tractus pyramidalis) connects the neurons of the motor cortex directly with the motor nuclei of the spinal cord and cranial nerves. the beginning of the way I
sense organs
The sense organs carry out the perception of various stimuli acting on the human and animal organism, as well as the primary analysis of these stimuli. Academician I.P. Pavlov defined the sense organs as
Organ of vision
The organ of vision is located in the orbit, the walls of which are formed by the bones of the brain and facial skull. The organ of vision consists of the eyeball with the optic nerve and auxiliary organs of the eye. K sur
Development of the organ of vision
Different parts of the eye develop from different embryonic buds. The inner shell of the eyeball is a derivative of the neural tube. The lens is formed from the ectoderm. Fibrous and vascular
Anomalies in the development of the eyeball in general
1. Anophthalmia - the absence of eyeballs. A) True anophthalmia (syn.: primary anophthalmia) is an extremely rare defect due to the lack of
Anomalies in the development of the lens
1. Afakia - the absence of the lens, a rare defect. A) Primary aphakia (syn.: true aphakia) - a violation of the differentiation of the ectoderm into the lens, with e
Anomalies in the development of the eyelids
1. Ankyloblepharon (syn.: isolated cryptophthalmos) - complete or partial fusion of the edges of the eyelids, often on the temporal side, leading to the disappearance or narrowing of the palpebral fissure.
Anomalies in the development of the optic nerve
1. Aplasia of the optic nerve - the absence of fibers - axons of retinal ganglion cells. It is observed in severe malformations of the central nervous system. 2. Hypoplasia of the optic nerve
vestibulocochlear organ
The vestibulocochlear organ is an organ of hearing and balance. It is located in the temporal region of the head, and most of it is located in the stony part (pyramid) of the temporal bone, arr.
Development of the vestibulocochlear organ
The inner, middle and outer ear are formed from rudiments of various origins. A 3.5-week-old embryo develops an auditory placode in the form of a thickening of the ectoderm on both sides of the rhomboid brain
Anomalies in the development of the organ of hearing
1. Agenesia (aplasia) of the external auditory canal - congenital absence of the external auditory canal, the result of impaired development of the I and II gill arches. 2. Agenesia
Olfactory organ
The olfactory organ in its peripheral section is represented by a limited area of the mucous membrane of the nasal cavity - the olfactory region covering the upper and partly the middle turbinates and upper
organ of taste
The organ of taste is represented by a collection of so-called taste buds located in the stratified epithelium of the lateral walls of the grooved, leaf-shaped and caps of the mushroom papillae of the tongue. In children, and
The structure of the nerves
Peripheral nerves consist of fibers that have a different structure and are not the same in functional terms. Depending on the presence or absence of the myelin sheath, the fibers are myelinated.
Development of the spinal nerves
The development of the spinal nerves is associated both with the development of the spinal cord and the formation of those organs that innervate the spinal nerves. At the beginning of the 1st month of intrauterine development
Formation and branching of the spinal nerves
In the formed human nervous system, there are 31 pairs of segmentally located spinal nerves, including 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal. In some with
Patterns of the course and branching of nerves
In their course and branching, nerves have much in common with blood vessels. In the walls of the body, the nerves, like the vessels, are located segmentally (intercostal nerves and arteries). Large nerve trunks
cranial nerves
Twelve pairs of cranial nerves do not have a regular segmental arrangement and cannot be considered homologues of the spinal nerves. Unlike the spinal nerves, which are similar to
Olfactory nerves
Olfactory nerves, nn. olfactorii are viscerally sensitive. They begin in the mucous membrane of the nasal cavity, in its olfactory region, which captures the upper part of the nose.
optic nerve
The optic nerve, n. opticus, is composed of axons of multipolar neurons of the ganglionic layer of the retina. These neurons are laid in the embryo in the inner plate of the visual b
Vestibulocochlear nerve
Vestibulocochlear nerve, n. vestibulocochlearis, conducts irritation from the receptors of the inner ear. It distinguishes vestibular and cochlear roots. Vestibular root, radix v
oculomotor nerve
Oculomotor nerve, n. oculomotorius, innervates most of the muscles of the eyeball: inferior rectus, inferior oblique, medial rectus, superior rectus, and levator superior
Abducens nerve
Abducens nerve, n. abducens, innervates the lateral rectus muscle of the eyeball. The nerve nucleus is located in the pons and is projected in the upper part of the rhomboid fossa, respectively.
hypoglossal nerve
Hypoglossal nerve, n. hypoglossus, is the motor nerve of the tongue. Its nucleus lies in the medulla oblongata and is projected in the lower medial part of the rhomboid fossa, respectively
Trigeminal nerve
Trigeminal nerve, n. trigeminus, is the main sensory nerve of the head. The area of skin innervation of this nerve is limited by the parieto-auricular-chin line and deviates kper
facial nerve
Facial nerve, n. facialis, is predominantly motor. It innervates the entire muscles of the face and part of the muscles of the neck (subcutaneous, posterior belly of the digastric, stylohyoid). dvig
Glossopharyngeal nerve
Glossopharyngeal nerve, n. glossopharyngeus, contains sensory, motor and parasympathetic fibers. The motor fibers of the nerve begin in the double nucleus, nucleus ambiguus,
Nervus vagus
Vagus nerve, n. vagus, is the nerve of the IV and V gill arches. The nerve nuclei are located in the medulla oblongata and are projected onto the inferolateral part of the rhomboid fossa, where
accessory nerve
Accessory nerve, n. accessorius (Willisian nerve), consists of motor fibers originating, according to some authors, in the nucleus of this nerve, nucleus nervi accessorii, located
autonomic nervous system
The autonomous, or autonomic, part of the nervous system is distinguished on the basis of its morphological and functional features. It is characterized by universal distribution in the body, innervation
Centers and general plan of the structure of the autonomic nervous system
In functional terms, three levels of regulation of autonomic functions can be distinguished, the morphological basis of which are: 1) the cerebral cortex; 2) reticular formation, cerebellum and l
Vegetative plexus of the abdominal cavity
The abdominal aortic plexus is formed around the abdominal part of the aorta and continues on its branches, giving rise to secondary plexuses. Celiac or solar plexus
Development of the heart
The complex and peculiar structure of the heart, which corresponds to its role as a biological engine, develops in the embryonic period. In the embryo, the heart goes through stages when its structure is similar to two
Age features and variability of the heart
The weight of the heart of a newborn boy is on average 23 g, a newborn girl - 21 g, which is about 0.7% of body weight. It has thin, stretchable walls. Relative mass and relatively
Anomalies in the shape, size and structure of the heart
1. Acardia (syn.: lack of heart) - observed only in non-viable fetuses. Most often occurs in free asymmetric twins, when one fetus is developed correctly.
Anomalies in the position of the heart
1. Dextrocardia (syn.: mirror dextrocardia) - isolated dextrocardia with the opposite, in relation to the usual, location in the chest cavity of the atria and ventricles (
Anomalies in the development of the septa of the heart
1. Ventricular septal defect - in most cases it is an integral part of complex defects. The frequency of observation of ventricular septal defects ranges from 12.1%
Anomalies of the inlet and outlet openings and valves of the heart
1. Aneurysm of the sinuses of the aorta (syn.: aneurysm of the sinuses of Valsalva) - stretching and thinning of the aortic wall in its ascending section in the region of the semilunar valves, in the region
Anomalies of the origin of the main vessels
1. The exit of the aorta and the pulmonary trunk from the left ventricle is a much rarer congenital defect than the double exit of vessels from the right ventricle. The aorta can occupy any of the 3
Combined heart defects
1. Lutembashe syndrome (Lutembacher syndrome, synonym: Lutembashe defect, morbus Lutembacher) - a combination of a congenital atrial septal defect with acquired mitral valve
Anomalies in the development of the pericardium
1. Defect of the pericardium - with splitting of the sternum, it can be in the anterior section, with a large defect, it is accompanied by prolapse of the heart (thoracic ectopia of the heart). Less often there is a defect in the side
Vessels of the heart
The oxygen demand of the heart is higher than that of other organs, with the exception of the brain. From 5 to 10% of all blood ejected from the left ventricle into the aorta passes through the heart. The heart is supplied with blood
Nerves of the heart
The efferent nerves of the heart belong to the autonomic nervous system. The heart is innervated by both sympathetic and parasympathetic nerves. In addition, the heart has an afferent innervation
Development of the arterial system
The circulatory system is laid in the human embryo very early - on the 12th day of intrauterine life. The beginning of the development of the vascular system is evidenced by the appearance in the surrounding yolk
Anomalies in the development of arteries
Violation of embryonic development leads to various anomalies of the arteries. The most common is agenesis (aplasia) or hypoplasia of one or another vessel. Impaired differentiation of the primary
The structure of the arteries
The principle of functional adaptation is clearly expressed in the structure of the arteries. The walls of the arteries resist the pressure of the blood; when blood passes through them, longitudinal and circular pressures occur.
Patterns of the course and branching of arteries
In 1881, P.F. Lesgaft formulated the “general law of angiology”, which stated that “vascular trunks are located along the concave side of the body and limbs; they are divided according to the division of the base, supply
Microcirculatory bed
Having passed through the branches of the arterial system, the blood reaches the microcirculatory bloodstream. Microcirculation is understood as the process of directed movement of fluids in the tissues surrounding the blood.
Age features of the microvasculature
The main directions of morphological and functional transformations of the hemomicrocirculatory bed in the postnatal period of ontogenesis are that, through adequate structural changes, separate
Venous system. Collateral circulation
The anatomical features of the venous system are determined by its role in the body and the conditions of blood flow in it. In the arteries, the blood flow is carried out under the influence of contractions of the heart and almost without
Vein development
In the prenatal period of ontogenesis in the development of venous vessels, the following stages can be distinguished: I - primary angiogenesis, that is, the formation of primary blood vessels from the mesenchyme in the foci of vasculae
Anastomoses of the veins of the head
Characteristic of the veins of the head is that many of them run independently of the arteries. In the cerebral region of the head, intracranial and extracranial veins are distinguished. The former include cerebral, meningeal
Cava-caval anastomoses
The subsystems of the superior and inferior vena cava are connected by anastomoses, which make up the group of cava-caval anastomoses. These include the veins of the anterior and lateral walls of the chest and abdomen, unpaired and sex
Porto-caval anastomoses
The portal vein forms porto-caval anastomoses with subsystems of both vena cava. There are upper, lower, anterior and posterior anastomoses. The upper porto-caval anastomosis is located in the area
Collateral circulation
It has long been noticed that when the vascular line is turned off, the blood rushes along roundabout ways - collaterals, and the nutrition of the disconnected part of the body is restored. The main source of development
General Anatomy of the Lymphatic System
Along with the circulatory system, which provides blood circulation in the body, most vertebrates and humans have a second tubular system, the lymphatic, with which the formation
Development of the lymphatic system
The development of the lymphatic system in phylogeny occurred in parallel with the improvement of the entire cardiovascular system. The lower vertebrates (lancelet, cyclostomes) have a single hemolymphatic
Structural organization of the lymphatic system
The human lymphatic system consists of several links: lymphatic capillaries, lymphatic vessels, lymph nodes, lymphatic plexuses, lymphatic trunks and lymphatic organs.
Lymphatic vessels and nodes of the lower limb
On the lower limb, superficial and deep lymphatic vessels are isolated. Superficial vessels collect lymph from the skin and subcutaneous tissue, and among them there are medial, lateral and posterior groups.
Lymphatic vessels and nodes of the small pelvis and abdominal cavity
Parietal lymph nodes of the pelvis are common, external and internal iliac, gluteal, obturator and sacral. The gluteal nodes receive lymph from the soft tissues of the gluteal region.
Lymphatic vessels and nodes of the head and neck
Lymphatic vessels of the organs of the head and neck flow into several groups of lymph nodes that are located on the border of the head and neck and in the neck. Outflow of lymph from the skin and muscles of the occipital
Lymphatic vessels and nodes of the upper limb
The lymphatic system of the upper limb is built according to the same plan as that of the lower limb. In the course of the lymphatic vessels of the forearm and shoulder, there are intercalated lymphatic nodules.
Lymphatic vessels and nodes of the chest
Of great practical importance is the lymphatic system of the mammary gland. It includes the superficial lymphatic capillaries of the skin covering it, and the small lymphatic vessels of the skin of the nipple, especially
List of used and recommended literature
Abdominal Endoscopic Surgery: Electronic manual on CD. - M .: Media Cordis, 2000. Abolina A.E., Abramov M.L. Atlas of congenital and acquired diseases of the musculoskeletal system
There are no isolated movements of one eyeball. Eye movements are always simultaneous and combined, which requires joint movement several external muscles of the eye, innervated at the same time by different nerves. On fig. 37 shows that, for example, when looking up, four muscles innervated from four cell groups of the nuclei of III nerves contract simultaneously; when looking down - two muscles innervated by the III nerves and two - from the IV nerves; when looking to the side, there is a simultaneous contraction of m. recti externi (VI nerve) of one and m. recti interni (III nerve) of the other eye; with convergence of the eye axes, both mm are reduced. recti interni from nuclei nn. oculomotorium; finally, a number of other combined muscle contractions occur with "oblique" directions of gaze, for example, to the right and up, etc. If we also take into account that with the contraction of any oculomotor muscles, the tone of the corresponding antagonist muscles must simultaneously decrease, then the need for a very fine and precise innervation system that regulates eye movements becomes clear.
Both reflex and voluntary movements of the eyeballs are always associated and joint. All this is due to the presence of a special connecting innervation system, which provides both internuclear (III, IV, VI nerves of both sides) connections, and connections of the nuclei of the eye muscles with other parts of the nervous system. Such a system is the posterior longitudinal bundle (fasciculus longitudinalis posterior, or medialis). The beam nuclei or Darkshevich nuclei are located anterior to the nn nuclei. oculomotorii, near habenula and comissura posterior.
The fibers of both bundles are directed down the brain stem, located in the bottom of the Sylvian aqueduct and the rhomboid fossa dorsally, on the sides and close to the midline and give collaterals to the cells of the nuclei of the III, IV and VI pairs of nerves, which ensures the compatibility and simultaneity of the movements of the eye muscles in that or some other combination.
Other fibers that make up the posterior longitudinal bundle are fibers from the cells of the vestibular nucleus, which go to the bundle of both their own and the opposite side. They branch into ascending and descending branches: those going upwards contact the cells of the nuclei of the eye muscles; descending - descend into the spinal cord, pass in it as part of the anterior columns and end near the cells of the anterior horns - tractus vestibulo-spinalis.
The "arbitrary" innervation of the gaze is carried out from the so-called "center" of the voluntary rotation of the eyes and head in the opposite direction, located in the posterior section of the second frontal gyrus. Fibers from the bark, approaching the bridge in its anterior section, cross and end near the nucleus n. abducentis of the opposite, therefore, side. From the nucleus of the VI nerve, the impulse simultaneously propagates along the nerve to m. rectus externus and to the cell group III of the nerve, giving fibers to m. rectus internus of the other eye, which causes a combined rotation of the eyeballs towards this nucleus (“bridge center of gaze”), but in the opposite direction to the hemisphere where the impulse originated. Therefore, when the second frontal gyrus is damaged, gaze paralysis is observed in the opposite direction, and when the bridge is damaged distally from the intersection of the central fibers in it or the nucleus n itself. abducentis, gaze paralysis is observed in the direction where the lesion is located. In both cases, due to the predominance of unaffected antagonists, a combined deviation of the eyeballs and head may occur with the defeat of the bridge - in the direction opposite to the focus; with damage to the cortical sections - towards the focus. With irritation of the posterior part of the second frontal gyrus (Jacksonian epilepsy), tonic convulsions of the eye muscles and head are observed in the direction opposite to the focus of irritation.
The system of the posterior longitudinal beam.
1 - the nucleus of the posterior longitudinal bundle (Darkshevich's nucleus); 2 and 5 - posterior longitudinal bundle; 3 - vestibular nerve; 4 - vestibulo-spinal bundle.
Localization of the cortical projection (ways) of turning the eyes up and down is not well understood; apparently, it is located near the projection of the turn to the side, at the base of the same second frontal gyrus. The fibers from here enter the system of the posterior longitudinal bundle through the nuclei n. oculomotorii. Processes in the region of the anterior colliculus - nuclear (III nerves) and perinuclear - are often accompanied by gaze paralysis up and down, just as foci in the bridge or in the region of the nuclei of VI nerves cause gaze paralysis to the side.
Table 11
A group of nerves of the eye muscles
Nuclei, their localization |
Out of the brain |
exit from the skull |
|
In the bottom of the Sylvian aqueduct, at the level of the anterior tubercles of the quadrigemina |
On the border of the legs of the brain and the bridge, on the medial side of the legs of the brain |
||
In the bottom of the Sylvian aqueduct, at the level of the posterior tubercles of the quadrigemina |
From the dorsal surface of the brain, behind the quadrigemina, crossing in the anterior cerebral velum |
Via fissura orbitalis superior |
|
In the bottom of the rhomboid fossa, in the colliculus facialis (in the bridge) |
On the border of the bridge and the medulla oblongata, at the level of the pyramids |
Via fissura orbitalis superior |
With damage to the posterior longitudinal beam, nystagmus is also observed.
The connections just analyzed determine the innervation of gaze from the cerebral cortex. Through the vestibular nucleus, the posterior longitudinal bundle establishes connections with the vestibular apparatus and the cerebellum. Connections with the extrapyramidal system are apparently carried out through the nuclei of Darkshevich. Descending fibers of the posterior longitudinal bundle cause connections with the spinal cord. Finally, there are connections between the nuclei of the eye muscles and the subcortical centers of vision and hearing (the anterior and posterior tubercles of the quadrigemina), which causes an "involuntary", reflex turn of the eyes and head in the direction of visual or auditory irritation.
