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Roof of the spinal tract diagram. Tectospinal tract

Anatomy of the nervous system pathways

After this, the fibers of the tractus tectospinalis are “directed” through the trunk to the segments of the spinal cord. In the tegmentum of the bridge, this path occupies a dorsomedial position, somewhat ventral to the longitudinal fasciculi.

A similar topography is observed in the medulla oblongata, where the tractus tectospinalis is located ventral to the medial longitudinal fasciculus and gradually moves ventrally, approaching the dorsal border of the pyramids. In the spinal cord it is located in the medial part of the anterior funiculus.

Gradually, the roof-spinal tract becomes thinner, as some of its fibers end on the motor neurons of the motor nuclei of the cranial nerves in the trunk (roof-nucleus bundle, fasciculus tectonuclearis) and in the overlying segments of the spinal cord.

Here, through interneurons, fibers of the tractus tectospinalis influence the alpha small motor neurons of the motor nuclei of the anterior horns.

Motor neurons of the trunk and spinal cord transmit influence through their axons from the integration center of the roof of the midbrain through the cranial and spinal nerves to the innervated skeletal muscles.

Damage to the tractus tectospinalis leads to the loss of starting reflexes to sudden light, sound, olfactory and tactile influences.

Reticulospinal tract

This pathway is considered the most phylogenetically oldest and nonspecific.

In this case, the name “tractus reticulospinalis” is understood as a set of efferent fibers starting from various centers of the reticular formation and having functional and topographical features.

In a simplified form, the reticulospinal tract can be depicted without decussation, without interneurons, without indicating the specific nucleus from which it originates, and as a single rather than multiple projection (Fig. 18).

Rice. 18. Reticulospinal tracts: 1 - reticular nuclei, 2 - reticulospinal tract, 3 - motor nuclei of the anterior horns of the spinal cord, 4 - spinal nerves

It should be taken into account what the target nucleus is in the spinal cord: in the case of the animal reflex arc, these are the motor nuclei of the anterior horn, and in the case of the sympathetic reflex arc, the intermediate-lateral nucleus of the lateral horn.

In other words, there are several parallel reticulospinal tracts.

The medial reticulospinal tract (tractus reticulospinalis medialis) is the most powerful and longest of the reticulospinal tracts.

It begins from the oral and caudal reticular nuclei of the pons and from the reticular nuclei of the medulla oblongata: giant cell and ventral.

In the spinal cord, it extends to the sacral segments, gradually thinning and ending segment by segment on the dendrites of the gamma motor neurons of the anterior horns of the spinal cord.

The lateral reticulospinalis tract (tractus reticulospinalis lateralis) begins from the lateral reticular nucleus of the pons, located near the middle cerebellar peduncle (regio parabrachialis).

This path is partially crossed, includes the axons of the reticular neurons of the respiratory center and then “descends” into the spinal cord, where it is located in the lateral cord next to the lateral corticospinal tract.

Tractus reticulospinalis lateralis has an activating effect on small alpha motor neurons of the anterior horns of the spinal cord.

Another part of its fibers ends on the neurons of the intermediate-lateral nucleus of the spinal cord (the center of the sympathetic division of the autonomic nervous system). Therefore, it becomes possible to regulate the organs of “plant life” from the reticular formation.

The anterior reticulospinalis tract (tractus reticulospinalis anterior) begins from the tegmental reticular nuclei of the midbrain and pons and, located in the anterior funiculi of the spinal cord, “reaches” the tenth thoracic segment. This pathway ends at the motor neurons of the anterior horns of the spinal cord.

All reticulospinal tracts are characterized by best expression in the cervical and upper thoracic segments of the spinal cord. More distally, the influence of the reticular formation spreads along the propriospinal tract. In other words, the reticulospinal tract is characterized by the shape of a chain of several sequentially located neurons (polysynaptic organization).

Another feature is that the reticulospinal tracts are predominantly uncrossed. All these pathways have an indirect connection with the motor neurons of the anterior horns, since they end on the dendrites of interneurons 7 and 8 of the Rexed plates and through them influence the motor neurons. These influences can be either inhibitory or activating.

As a result, the reticular formation, through its reticulospinal tracts and spinal nerves, ensures the tone of skeletal muscles and the performance of complex reflex acts that require the simultaneous participation of many skeletal muscles or even muscle groups (respiratory, grasping movements).

Similar relationships exist between the centers of the reticular formation and the nuclei of the cranial nerves.

vestibulospinal tract

This path also refers to very ancient projections in evolutionary terms, closely related to the vestibular analyzer.

Tractus vestibulospinalis is involved in the body’s rapid response to such a change in body position in space, which leads to imbalance.

In this case, unconditional reflex body movements occur, leading to the fact that a person, having slipped, falls on his outstretched arms and does not hit his head or torso.

This path begins from the lateral vestibular nucleus (Deiters nucleus) (nucl. vestibularis lateralis), located in the tegmentum of the bridge near the border of the latter with the medulla oblongata (Fig. 19).

Rice. 19. Vestibulospinal tract: 1 - vestibular nuclei, 2 - vestibular tract, 3 - motor nuclei of the anterior horns of the spinal cord, 4 - spinal nerves

According to a number of researchers, the tractus vestibulospinalis also includes axons of neurons whose bodies are located in the inferior vestibular nucleus (Roller’s nucleus). The latter is located next to Deiters' nucleus, but somewhat more caudally.

The Deiters nucleus has an indirect effect (in particular, through the alpha motor neurons of the motor nuclei of the anterior horns of the spinal cord) on the extensor muscles and is thus a kind of antagonist of the red nucleus.

In the medulla oblongata, the vestibulospinal tract is located dorsal and lateral to the pyramids, and in the spinal cord - on the border of the anterior and lateral cords (here it is penetrated by fibers of the anterior roots of the spinal nerves). The path is mostly uncrossed.

Olivespinal tract

Tractus olivospinalis is involved in the unconditioned reflex maintenance of neck muscle tone and in performing movements designed to maintain body balance.

This path is relatively young in evolutionary terms, like the olive nucleus (nucleus olivaris) of the medulla oblongata, from which it begins.

The olive nucleus has a regulatory influence on the cerebellar hemispheres (cortex and dentate nucleus), the red nucleus and the cortex of the frontal lobe of the cerebral hemisphere.

Axons of neurons nucl. olivaris as part of the tractus olivospinalis reach the sixth cervical segment of the spinal cord, ending segment by segment on the alpha motor neurons of the motor nuclei of the anterior horns on their side of the body (Fig. 20).

Rice. 20. Olivospinal tract: 1 - nuclei of the inferior olive, 2 - olivospinal tract, 3 - motor nuclei of the anterior horns of the spinal cord, 4 - spinal nerves, 5 - neck muscles

The axons of these motor neurons as part of the spinal nerves reach the neck muscles, which innervate them. In the spinal cord, the olivospinal tract is located in the anteromedial part of the lateral funiculus.

3.2. Pyramid paths

These pathways, collectively called the “pyramidal system,” are involved in the conscious control of skeletal muscle function (stimulating or inhibiting contraction). In particular, it is possible to perform voluntary movements characterized by complexity and accuracy.

The pyramidal system consists of two pathways: the corticospinal tract (tractus corticospinalis) and the corticonuclear tract (tractus corticonuclearis). The pyramidal system received its name due to the fact that the tractus corticospinalis “passes” through the pyramids of the medulla oblongata.

It is clear that the name is not very good, since the main thing here is not topography, but function.

Corticospinal tract

This pathway conducts volitional motor impulses that allow control of skeletal muscles innervated by spinal nerves, i.e. muscles of the limbs, trunk and neck. The corticospinal tract also conducts impulses that can inhibit the activity of motor neurons in the anterior horns of the spinal cord.

Source: https://medread.ru/anatomiya_provodyashhix_putej_nervnoj_sistemy/11/

Motor pyramidal tract. Symptoms of damage to the pyramidal tract

Our brain is a unique multi-complex system that simultaneously controls the sensory and vestibular apparatus, movement, thinking, speech, vision and much more.

In this article we will talk about how the brain controls voluntary and involuntary movement. And about what neurological abnormalities there are that are associated with damage to the pyramidal system of the brain.

Pyramidal and extrapyramidal tract

The pyramidal system consists of pyramidal and extrapyramidal tracts. What is their difference? The pyramidal tract, or tractus pyramidalis, is a pathway that connects cortical neurons responsible for motor activity with the nuclei of the spinal cord and cranial nerves.

Its job is to control voluntary muscle movements by transmitting signals from the central nervous system to the body. But the extrapyramidal one, it controls the unconscious conditioned reflexes of our body. This is an older and deeper structure of the brain, and its signals are not reflected in consciousness.

Extrapyramidal and pyramidal are descending pathways. And the ascending main pathways are responsible for transmitting information from the senses to the brain. These include: the lateral spinothalamic tract, the anterior spinocerebellar tract and the posterior spinocerebellar tract.

Pyramidal tracts of the brain. Structure

They are divided into 2 types: corticospinal and corticonuclear. The corticospinal cord is responsible for the movements of the torso, the cortico-nuclear cord controls the facial and swallowing muscles.

How does the corticospinal pyramidal tract work? This electrical path begins with the cerebral cortex - the area that is responsible for higher mental activity, for consciousness. The entire cortex is made up of interconnected neural networks. More than 14 billion neurons are concentrated in the cortex.

In the hemispheres, information is redistributed in this way: everything that concerns the work of the lower extremities is in the upper sections, and everything that concerns the upper, on the contrary, is in the lower structures.

All signals from the upper and lower parts of the cortex are collected and transmitted to the internal capsule. Then, through the midbrain and through the middle part of the pons, a bundle of nerve fibers enters the pyramids of the medulla oblongata.

Here branching occurs: most of the fibers (80%) pass to the other side of the body and form the lateral spinal tract. These branches “launch” motor neurons, which then transmit signals to contract or relax directly to the muscles. A smaller part of the fiber bundle (20%) innervates the motor neurons of “their” side.

The corticonuclear pyramidal tract initially passes through the same brain structures as its “partner”, but crosses over in the midbrain and goes to the facial neurons.

Anatomical features important for diagnosis

The pyramidal pathway has some structural features that should not be overlooked when it is necessary to determine the localization of the pathology. What specific features do you need to know?

  1. Some of the nerve fibers of the corticospinal tract, in addition to the lateral decussation, also intersect in the area of ​​the white commissure of the spinal cord segment, where they end.
  2. Most of the muscles in the trunk are controlled by both hemispheres of the brain. This is an important protection. In the event of a stroke or stroke, those patients diagnosed with hemiplegia can support the body upright.
  3. In the area of ​​the pons, the fibers of the corticospinal tract are separated by other fibers - the cerebellar tract. Divided bundles emerge from the bridge. In this regard, movement disorders are often dispersed. Whereas the pathological focus may be single.

Symptoms of damage to the pyramidal tract are sometimes quite obvious, as in the case of paraplegia, for example. But sometimes it is difficult to determine the cause. It is important to notice minor disturbances in motor skills in time and see a doctor.

Symptoms of defeat. Levels

Clinical manifestations of pyramidal tract disorders depend on the specific part of the nerve fibers damaged. There are several levels of damage to motor activity: from complete paralysis to relatively favorable impairments.

So, neurology identifies the following levels of damage to the pyramidal tract:

  1. Central monoparesis (paralysis). The disorders are localized in the cerebral cortex (left or right).
  2. Central hemiparesis. The internal capsule is damaged.
  3. Various alternating syndromes - the brain stem area is affected.
  4. Paralysis of limbs. One of the lateral cords in the spinal cord.

Central paralysis with damage to the brain capsule and cerebral hemispheres is characterized by the fact that muscle function is impaired on the opposite side of the body relative to the affected area.

After all, the intersection of the pyramidal tract works in the nervous system. That is, the fibers move to the lateral or lateral spinal tract.

The simplified diagram shows how the pyramidal path, the anatomy of which was discussed above, crosses and moves on.

If the lateral cord in the spinal cord is damaged, the work of the muscles on the same side as the damage is disrupted.

Neuropathology. Peripheral and central paralysis

Nerve fibers look like cords under a microscope. Their work is extremely important for the body. If conduction in some part of the nerve chain is disrupted, muscles in some parts of the body will not be able to receive signals. This will cause paralysis. Paralysis is divided into 2 types: central and peripheral.

If one of the central motor nerves in the “network” is disrupted, central paralysis occurs. And if there is a problem with the peripheral motor nerve, the paralysis will be peripheral.

With peripheral paralysis, the doctor observes a decrease in muscle tone and a severe decrease in muscle mass. Tendon reflexes will also be reduced or disappear completely.

The situation is different with central paralysis. Then hyperreflexia is observed, muscle tone is increased, and contractures are sometimes present.

Pyramidal insufficiency in newborns. Reasons

Symptoms of motor impairment in a child include strange jerking movements, or he may walk differently than other children - on tiptoes; or the placement of the feet is incorrect. The reasons for this condition in a child may be:

  • underdevelopment of the brain (spinal or brain);
  • birth trauma, if the parietal lobe of the brain or the brain stem itself is damaged, there will definitely be disturbances in the pyramidal tract;
  • hereditary diseases of the nervous system.
  • hypoxia;
  • cerebral hemorrhage after childbirth;
  • infection such as meningitis or arachnoiditis.

Treatment for adults is often medicinal. But for children it is much better to use methods such as exercise therapy, massage and taking vitamins. If there are no brain abscesses or other serious injuries, the condition improves by the first year of life.

Paresthesia and myoclonus

Disturbance in the cervical spine leads to paresthesia. This is a neuropathy that is characterized by impaired sensitivity. A person may either lose touch sensation in the skin altogether or experience tingling sensations throughout the body. Paresthesia is treated with reflexology, manual therapy or physiotherapy. And, of course, you need to remove the main cause of neuropathy.

Another lesion of the pyramidal tracts and, consequently, motor activity is myoclonus - involuntary twitching.

There are several types of myoclonus:

  • rhythmic myoclonic contractions of a separate muscle group;
  • velopalatine contractions - sudden non-rhythmic contractions of the tongue or pharynx;
  • postural myoclonus;
  • cortical;
  • myoclonus in response to physical activity (in athletes).

Myoclonus or cortical myoclonus is a disease of the nerve pathway caused by a disorder in the motor centers of the brain. That is, at the very beginning of the pyramid path. If there is a “failure” in the cortex, the signals reach the muscles already distorted.

However, the causes of disturbances in the motor pyramidal tract can be a lack of magnesium, psycho-emotional or physical fatigue, and many other reasons. Therefore, the diagnosis must be made by a doctor after checking with an MRI.

Diagnosis of disorders

The descending pyramidal tract is a projection one, while the ascending tract is considered to be the one that transmits body signals through the spinal cord to the central nervous system. Descending, on the contrary, transmits brain signals to neurons.

To determine which system has been damaged and to what extent, during the examination, the neurologist examines many parameters relating to muscles, joints, and nerve reflexes.

A neurologist performs the following diagnostic procedures:

  • examines the range of motion of all joints;
  • checks deep reflexes, looks for pathological reflexes;
  • checks the functioning of all facial nerves;
  • measures electrical conductivity of muscles, their biopotentials;
  • examines muscle strength;
  • and is also required to check whether pathological clonic contractions are present.

When a neurologist checks range of motion, he begins by examining the larger joints first, and then examines the smaller ones. That is, first examines the shoulder joint, then the elbow and wrist.

Damage to the corticonuclear tract

The pyramidal path is the basis of all movements not only of the muscles of the body, but also of the face. The axons of various facial motor neurons transmit signals to the muscles. Let's take a closer look. The motor neurons of the nucleus ambiguus innervate the muscles of the pharynx, larynx, soft palate, and even the muscles of the upper esophagus.

Motor neurons of the trigeminal nerve are responsible for the work of some muscles of mastication and those that give the signal to the eardrum to contract. Individual motor neurons contract the facial muscles when we smile or frown. These are facial neurons.

Another group of muscles is responsible for eye and eyelid movements.

The defeat of the leading neuron affects the work of the “subordinate” muscles. The entire pyramidal path is based on this principle. Neurology of the facial nerve leads to very unpleasant consequences. However, eye movements and swallowing are usually preserved.

It is worth noting that complete disconnection of the facial muscles from the controlling segment of the brain occurs only if both the right and left hemispheres are affected. Most facial neurons are controlled bilaterally, as are the muscles of the trunk. One-way crossed fibers go only to the lower part of the face, namely to the muscles of the tongue and lower jaw.

Damage to motor areas of the cerebral cortex

When motor areas in the cortex of one hemisphere are damaged as a result of injury, a person becomes paralyzed on one side. When both hemispheres are damaged, the paralysis is bilateral. If these centers experience overexcitation, local or centralized convulsions are caused. Frequent seizures may indicate the development of epilepsy.

Symptoms of damage to the pyramidal tract at the level of the brain stem

Since fiber crossover occurs at the level of the brain stem (the medulla oblongata and the pons), when these structures are damaged, gamiplasia occurs on the other half of the body. This symptom is called alternating paralysis.

The pyramidal tract is the basis of fine motor skills. If the brain stem is even slightly damaged, fine movements of the fingers are greatly affected.

There are many different syndromes that clearly and in detail characterize disorders that affect the work performed by the pyramidal tract: Avellis, Schmidt, Wallenberg-Zakharchenko syndromes and others. Based on the symptoms of these syndromes, the doctor can often determine the exact location of the pathway disorder before testing.

The body of the first neuron is the giant pyramidal cell of Betz of the anterior central gyrus cortex. Through the internal capsule, the axons go to the bodies of the second neurons - the cells of the motor nuclei of the cranial nerves.

Starting from the midbrain and further, in the pons and in the medulla oblongata, the fibers of the cortical-nuclear tract pass to the opposite side to the motor nuclei of the cranial nerves: to the nuclei of the III and IV pairs - in the midbrain; to the nuclei of V, VI, VII pairs - in the bridge; to nuclei IX, X, XI, XII pairs - in the medulla oblongata.

Rice. 38. Pyramidal tracts (anterior and lateral corticospinal tracts) ( ABOUT . Feitz , 2009).

III– alpha motor neurons of the anterior horns of the spinal cord

Their axons, as part of the cranial nerves, go to the muscles of the head and neck (Fig. 39).

Rice. 39. Pyramidal tracts (cortical-nuclear tracts)

(O. Feitz, 2009).

I– giant pyramidal cells of Betz;II– nuclei of cranial nerves (III- XIIa couple).

Extrapyramidal tracts

Extrapyramidal tracts conduct impulses to muscles from the basal ganglia, thalamus optic, red nucleus, substantia nigra, olive nucleus, vestibular nerve, reticular formation. The extrapyramidal system automatically maintains skeletal muscle tone.

Extrapyramidal pathways include:

– red nuclear spinal tract (tractus rubrospinalis);

– vestibulospinal tract (tractus vestibulospinalis);

– reticulospinal tract (tractus reticulospinalis);

– tectospinal tract (tractus tectospinalis);

Red nuclear spinal tract (Monakova)

The red nucleus-spinal tracts originate from the red nucleus, pass to the opposite side (Trout decussation), pass in the tegmentum of the bridge, in the lateral sections of the medulla oblongata and descend as part of the lateral cord of the spinal cord to the motor neurons of the spinal cord.

Their axons leave the spinal cord in the anterior roots and are directed as part of the spinal nerves to the skeletal muscles (Fig. 40).

Rice. 40. Extrapyramidal tracts

(Rednuclear spinal tract (Monakova) (O. Feitz, 2009)

I– red nucleus of the midbrain;II- anterior horns of the spinal cord.

vestibulospinal tract

The vestibulospinal tract is important in coordinating the motor functions of the body. It connects the nuclei of the vestibular nerves with the motor neurons of the anterior horns of the spinal cord and is involved in controlling the body’s adjustment reactions when balance is disturbed. Axons of neurons of the lateral vestibular nucleus (Deiters nucleus), as well as the inferior vestibular nucleus (descending root) of the vestibulocochlear nerve, take part in the formation of the vestibular tract.

These fibers descend as part of the anterior funiculus of the spinal cord and end on the motor neurons of the anterior horns of the spinal cord. The nuclei forming the vestibulospinal tract are in direct communication with the cerebellum, as well as with the medial longitudinal fasciculus, which is connected with the nuclei of the oculomotor nerves. The presence of such a connection makes it possible to maintain the direction of the visual axis when turning the head and neck (Fig. 41).

The tectospinal tract, tractus tectospinalis, is a descending motor tract belonging to the extrapyramidal system. It carries out unconditional reflex motor reactions in response to sudden strong visual, auditory, tactile and olfactory stimulation. The first neurons of the tegmental spinal tract are located in the superior colliculus of the midbrain in the subcortical integration center of the midbrain. This integration center receives information from the subcortical centers of vision (nucleus of the superior colliculus), from the subcortical center of hearing (nucleus of the inferior colliculus), from the subcortical center of smell (nucleus of the papillary body) and collaterals from the conduction pathways of general sensitivity (lemniscus spinalis, lemniscus medialis, lemniscus trigeminalis).

The axons of the first neurons are directed ventrally and upward, bypass the central gray matter of the midbrain and pass to the opposite side. The intersection of the fibers of the tegmental spinal tract with the tract of the same name on the opposite side is called the dorsal decussation of the tegmentum, decussatio tegmenti dorsalis. This chiasm is also called the fountain-shaped chiasm, or the chiasm of Meynert, which reflects the nature of the course of the nerve fibers. The tract then passes in the dorsal part of the pons next to the medial longitudinal fasciculus. Along the tract in the brain stem there are
fibers that end on motor neurons of the motor nuclei
cranial nerves. These fibers are united under the name tectonuclear bundle, fasciculus tectonuclearis. They provide protective reactions involving the muscles of the head and neck.

In the region of the medulla oblongata, the tectospinal cord
the path approaches the dorsal surface of the pyramids and is directed into the anterior cord of the spinal cord. In the spinal cord it occupies
the most medial part of the anterior funiculus, limiting the anterior
median gap.



The tectospinal tract can be traced throughout the entire spinal cord. Gradually becoming thinner, it gives off segment-by-segment branches to the alpha small motor neurons of the motor nuclei of the anterior horns of the spinal cord on its side. The axons of motor neurons conduct nerve impulses to the muscles of the trunk and limbs.

When the tegnospinal tract is damaged, they disappear
starting reflexes, reflexes to sudden sound, auditory,
olfactory and tactile stimulation.

Reticular spinal tract

The reticular-spinal tract, tractus reticulospinalis - the descending, efferent pathway of the extrapyramidal system - is designed to perform complex reflex acts (respiratory, grasping movements, etc.), requiring the simultaneous participation of many groups of skeletal muscles. Consequently, it plays a coordinating role in these movements. The reticular-spinal cord 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. Except
In addition, this pathway transmits impulses to gamma motor neurons, providing the tone of skeletal muscles.

The first neurons of the reticular spinal tract are located in the reticular formation of the brain stem. The axons of these
neurons go in a descending direction. In the spinal cord they form a bundle, which is located in the anterior cord. The bundle is well defined only in the cervical and upper thoracic regions of the spinal cord. It thins out segment by segment, sending fibers to the gamma motor neurons of the motor nuclei of the anterior horns of the spinal cord. The axons of these neurons project to the skeletal muscles.

vestibulospinal tract

The vestibulospinal tract, tractus vestibulospinalis, is the descending motor pathway of the extrapyramidal system. It provides unconditioned reflex motor acts in case of imbalances in the body. The vestibulospinal tract is formed by axons of cells of the lateral and inferior vestibular nuclei (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 vestibulospinal tract end segment by segment on the alpha motor neurons of the motor nuclei of the anterior horns of the spinal cord. The axons of motor neurons as part of the spinal nerve roots leave the spinal cord and go to the skeletal muscles.

Olive-spinal tract

Olive-spinal tract, tractus olivospinalis, - descending
motor pathway of the extrapyramidal system It provides unconditional reflex maintenance of neck muscle tone and motor acts aimed at maintaining body balance.

The olivospinal tract begins from the neurons of the inferior olivary nucleus of the medulla oblongata. Being a phylogenetically new formation, the inferior olivary nucleus has direct connections with the cerebral cortex of the frontal lobe (cortical-olive tract, tr. corticoolivaris), with the red nucleus (red nucleus olivary tract, tr. rubroolivaris) and with the cortex of the cerebellar hemispheres (olivo-cerebellar tract, tr olivocerebellatis). The axons of the cells of the inferior olive nucleus are collected in a bundle - the olivo-spinal tract, which passes in the anteromedial section of the lateral cord. It can be traced only at the level of the six upper cervical segments of the spinal cord.

The fibers of the olivospinal tract end segment by segment on the alpha motor neurons of the motor nuclei of the anterior horns of the spinal cord.
brain The axons of motor neurons as part of the spinal nerve roots leave the spinal cord and go to the muscles of the neck.

Medial longitudinal fasciculus

Medial longitudinal fasciculus, fasciculus longitudinalis medialis
is a combination of descending and ascending
fibers that carry out coordinated movements of the eye
“block and heads. This function is necessary to maintain equilibrium
this body. Performing this function becomes possible only
but as a result of the morphofunctional connection between the nerve centers
frames that provide innervation to the muscles of the eyeball (motors)
body nuclei of the III, IV and VI pairs of cranial nerves), centers,
responsible for the innervation of the neck muscles (motor nucleus XI pair
and motor nuclei of the anterior horns of the cervical segments of the spinal
brain), center of balance (Deiters nucleus). The work of these centers is coordinated by the neurons of the large nuclei of the reticular formation -
intermediate nucleus, nucleus interstitialis (Cajal's nucleus), - and the nucleus of the posterior commissure, nucleus commissuraeposterior (Darkshevich's nucleus).

The intermediate nucleus and the nucleus of the posterior commissure of the brain are located
and the rostral part of the midbrain, in its central gray matter. The axons of the neurons of these nuclei form the medial longitudinal fasciculus, which passes under the central gray matter
near the midline. Without changing its position, it continues in the dorsal part of the pons and deviates in the ventral direction in the medulla oblongata. In the spinal cord it is located in
anterior funiculus, in the angle between the medial surface of the anterior
horns and anterior white commissure. The medial longitudinal fasciculus can be traced only at the level of the upper six cervical segments.

Within the midbrain as part of the medial longitudinal fasciculus
fibers come from the posterior longitudinal bundle, which unites
iegetative centers. This connection between the medial and posterior longitudinal fasciculi explains the resulting autonomic reactions
with vestibular loads. From the medial longitudinal fasciculus fibers are directed to the motor nucleus of the oculomotor nerve.

This nucleus has five segments, each of which is responsible for the innervation of certain muscles: neurons of the upper segment
(1st) innervate the muscle that lifts the upper eyelid; 2nd - rectus eye muscle; 3rd - inferior oblique muscle of the eye; 4th - inferior rectus muscle of the eye; 5th - medial rectus muscle of the eye.
Neurons of the 1st, 2nd and 4th segments receive fibers from the medial longitudinal fasciculus on their side, neurons of the 3rd segment - from the opposite side. Neurons of the 5th segment also close to
the central unpaired nucleus (convergence) and are connected with the medial longitudinal fasciculus on their side. They provide the possibility of movement of the eyeball to the medial side and the simultaneous convergence of the eyeballs (convergence).

Further, within the midbrain, fibers from the medial longitudinal fasciculus 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 medial longitudinal fasciculus includes the axons of the cells of the Deiters nucleus (VIII pair - vestibulocochlear nerve),
which go in an ascending direction to the neurons of the intermediate
kernels. Fibers extend from the medial longitudinal fasciculus to neurons
motor nucleus of the abducens nerve (VI pair), 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 fasciculus, fibers are directed to the neurons of the motor nucleus
accessory nerve (XI pair) and motor nuclei of the anterior horns
six upper cervical segments, responsible for the work of the neck muscles.

In addition to the general coordination of the muscles of the eyeball and head, the medial longitudinal fasciculus performs an important integrative
role in the activity of the eye muscles. Communicating with nuclear cells
oculomotor and abducens nerves, it ensures the coordinated function of the external and internal rectus muscles of the eye, manifested in a combined rotation of the eyes to the side. In this case, a simultaneous contraction of the external rectus muscle of one eye and the internal rectus muscle of the other eye occurs.

When the intermediate nucleus or medial longitudinal fasciculus is damaged, the coordinated functioning of the muscles of the eyeball is disrupted. Most often this manifests itself in the form of nystagmus (frequent contractions of the muscles of the eyeball, directed in the direction of movement, when the gaze stops). Nystagmus can be horizontal, vertical and even rotatory (rotational). Often these disorders are supplemented by vestibular disorders (dizziness) and autonomic disorders (nausea, vomiting, etc.).

Posterior longitudinal fasciculus

The posterior longitudinal fasciculus, fasciculus longitudinalis dorsalis, is a set of descending and ascending fibers that communicate between the autonomic centers of the brain stem and spinal cord. The posterior longitudinal fasciculus (fasciculus of Schütz) 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. It then passes in close proximity to the midbrain aqueduct. Already in the midbrain, some of the fibers of the posterior longitudinal fasciculus are directed to the accessory nucleus of the oculomotor nerve. In the area of ​​the bridge, fibers extend from it to the lacrimal and
superior salivary nuclei of the facial nerve. In the medulla oblongata, fibers branch to the inferior salivary
the nucleus of the glossopharyngeal nerve and the dorsal nucleus of the vagus nerve.
In the spinal cord, the posterior longitudinal fasciculus is located in the form of a narrow ribbon in the lateral funiculus, next to the lateral corticospinal tract. The fibers of the Schütz bundle end segment by segment 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 fasciculus is isolated at the level of the lumbar segments and is located near the central canal. This bundle is called periependymal. 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 brain stem or spinal cord as part of the cranial or spinal nerves and are directed to the internal organs, vessels and glands. So the rear
the longitudinal fasciculus plays a very important integrative role in the regulation
lation of vital body functions.

tectospinal tract)

projection descending nerve pathway, starting in the superior colliculi of the roof of the midbrain, passing through and anterior, ending in its anterior horns.


1. Small medical encyclopedia. - M.: Medical encyclopedia. 1991-96 2. First aid. - M.: Great Russian Encyclopedia. 1994 3. Encyclopedic Dictionary of Medical Terms. - M.: Soviet Encyclopedia. - 1982-1984.

See what “tegnospinal tract” is in other dictionaries:

    - (tractus tectospinalis, PNA, BNA, JNA; synonym tectospinal tract) projection descending nerve tract, starting in the superior colliculi of the midbrain roof, passing through the brain stem and anterior cord of the spinal cord, ending in its... ... Large medical dictionary

    Large medical dictionary

    - (tractus tectospinalis; anat. tectum mesencephali roof of the midbrain) see tectal spinal tract ... Medical encyclopedia

    - (medulla spinalis) part of the central nervous system located in the spinal canal. S. m. has the appearance of a white cord, somewhat flattened from front to back in the area of ​​thickening and almost round in other sections. In the spinal canal... ... Medical encyclopedia

    Spinal cord- (medulla spinalis) (Fig. 254, 258, 260, 275) is a cord of brain tissue located in the spinal canal. Its length in an adult reaches 41-45 cm, and its width is 1-1.5 cm. The upper part of the spinal cord smoothly passes into... ... Atlas of Human Anatomy

    Pathways of the nervous system- Conscious sensory pathways are conductors that carry nerve impulses to the cerebral cortex. Depending on the location of the receptors, which determines the nature of the impulses, the pathways are divided into... ... Atlas of Human Anatomy

    Diagram of the location of pathways in the white matter and nuclei in the gray matter on a cross section of the spinal cord- thin and wedge-shaped beams; thin and wedge-shaped beams; own (posterior) bundle; posterior spinal cerebellar tract; lateral pyramidal (cortical spinal) tract; own bundle (lateral); red nuclear spinal tract; ... ... Atlas of Human Anatomy

    The central nervous system (tractus sistematis nervosi centralis) is a group of nerve fibers that are characterized by common structure and functions and connect various parts of the brain and spinal cord. All nerve fibers of one path begin from... Medical encyclopedia

    - (ki) (fasciculus, i, PNA, BNA, JNA) in anatomy, a set of fibers (nerve, connective tissue or muscle), united anatomically and functionally. Arnold's bundle see Frontal bridge path. Atrioventricular bundle (f. atrioventricularis ... Medical encyclopedia

    Brain: Midbrain Latin name Mesencephalon Midbrain ... Wikipedia