The components of the reflective arcs ending in certain tiers of the brain are called the conductive spinal tracts. Through these tracts, various points of the brain can communicate with the corresponding branches and, quickly receiving and subsequently transmitting reflective or sympathetic urges. Descending pathways are designed to send impulses from the brain to the spinal cord, and ascending pathways are the opposite. Ascending and descending pathways spinal cord control the work internal organs person.

The essence of the spinal conduction mission

Pathways are special neural fibers that transmit signals of a certain kind to various brain centers.
It is customary in medical practice to differentiate the three groups of the above fibers.

• Associative. They are intended to connect gray matter cells from dissimilar segments to form, directly near the gray matter, special own bundles (meaning anterior, lateral, posterior).
• Commissory. The function of these fibers is to connect the gray matter from both hemispheres, as well as similar and equidistant nerve centers of both halves of the brain for correlation and coordination of their work.
• Projection. These fibers connect the overlying and underlying brain regions. They are responsible for projecting pictures of the surrounding world onto the cerebral cortex, like on a scoreboard or television screen.

Projection fibers differ depending on the direction of the impulses sent to the ascending and descending pathways.
For the supply of signals to the brain, manifested as a result of influence on human body various factors and phenomena external environment, correspond to the following three groups of ascending paths.

• Exteroceptive - supply impulses from two types of receptors.

1. Impulses supplied by exteroreceptors. This refers to temperature, tactile and pain signals.
2. Sensory impulses: the ability to see, hear, distinguish between smells and tastes.

• Proprioceptive - responsible for the impulses coming from the organs of movement and muscles.
• Interoceptive - designed to conduct impulses that are sent by internal organs.

The descending pathways carry signals from the subcortical centers and the cortex itself to the nuclei of the brain, as well as to the motor nuclei of the spinal horns located in front. Downstream pathways include several fiber systems.

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1. The cortico-spinal cord is responsible for the mission of movement.
2. The tectospinal tract, otherwise known as the tectospinal pathway, is a projection descending nervous system.
3. Vestibular-spinal - responsible for proper coherence in the work of the vestibular apparatus.
4. The mesh-spinal cord, otherwise called the reticular-spinal cord, provides the proper level of muscle tissue tone.

In addition, the pathways of the brain and spinal cord are also differentiated according to the tasks performed.

• The motor pathways responsible for the reflex response. Their task is to transmit "pointers" from the brain to the spinal cord and further to the muscles. Thanks to the coordinated work of these paths, the proper level of coordination of movement is ensured.
• Sensory pathways help in recognizing pain, temperature and its changes, tactile sensations.

Nerve fibers are the guarantors of the inextricable relationship between the brain and the spinal cord, and through it - with all organ systems. The rapid transmission of appropriate signals ensures the consistency of all body movements, excluding significant efforts made by the person himself. Pathways form bundles of nerve cells.

Types of conducting paths by direction

The ascending pathways of the spinal cord recognize the urges received from various life-supporting organs of a person, with their subsequent provision to the "center".

Ascending and descending tracts connect the spinal horns to the cerebral cortex

Descending pathways send "instructions" immediately to certain internal organs, various glands, as well as muscles. Signals and impulses in this case are transmitted through the spinal neural connection.

Fast and accurate data transmission is ensured thanks to the double course of the spinal cords.

Localization of paths in the course of their movement

The ascending and descending tracts connect the spinal horns to the cerebral cortex. The spinal tracts are nerve bundles and tissues that run in the corresponding areas of the brain. In this case, impulses can only be transmitted in one direction. The location of the spinal tracts is clearly demonstrated by the diagram in the above video.

Ascending spinal pathways and their characteristics

The bodies of the first nerve cells, acting as transmitters of various types of spinal sensitivity, lie in the corresponding brain ganglions. Cellular axons of these nodes enter the spinal part. Among them, there are a couple of groups.

The medial group moves towards the posterior funiculus. At this point, each existing fiber splits into a pair of branches. They are called ascending and descending. A certain number of the above branches, when moving up and down, form bundles in various spinal segments and points.

ascending paths of the spinal cord, otherwise called centrifugal or afferent, with their characteristics and direction of movement, are described in detail in Table 1.

No. p / p	View of the ascending path	Characteristics
1	Posterior spinocerebellar	The task of this direct cerebellar pathway is to conduct impulses to the cerebellum from muscle receptors. The spinal ganglion is the home of the first neurons. The resting place of the second neurons is the entire surface of the spinal cord in the thoracic nucleus. These neurons move towards the outside. Having reached the posterior external spinal section, they turn up and follow close to the lateral spinal cord. Then they go to the cortex of the cerebellar worm.
2	Anterior spinocerebellar	This tract is also designed to conduct impulses to the cerebellum from muscle receptors. The spinal ganglion is the nesting place of the first neurons. And the medial nucleus of the intermediate section is the habitat of the bodies of the second neurons. Their fibers are sent to the lateral cords of both sides. Having reached the anteroexternal divisions of the cords, the fibers will be located above the posterior spinal cerebellar tract. Wrapping up, crossing the bridge and making a cross, the fibers reach the cerebellar vermis, which completes this path.
3	dorsal-olive	Let this ascending conductor begin in the cells back horns. After crossing, the axons of these cells move upward along the spinal surface. The final destination of the spinal-olive tract are, respectively, the kernels of the olive. Data from muscle and skin receptors enter the brain through the above tract.
4	Anterior spinothalamic	Responsible for the transmission of signals regarding tactile sensitivity.	The spinal ganglia are the location of the bodies of the first neurons. The path of the second neurons lies on the opposite side towards the cords. The fibers of these pathways, bypassing the medulla oblongata, pons and cerebral peduncles, subsequently reaching the thalamus. The third neurons lie precisely in the thalamus, following directly to the cerebral cortex.
5	Lateral spinothalamic	Carries out the wiring of signals regarding temperature and pain sensations.
6	spinal reticular	The elements of this tract are fibers from both spinal-thalamic paths.	These two paths run through the lateral spinal cords, ending in the midbrain roof plate.
7	Dorsal tegmental
8	thin beam	This bundle transmits "instructions" directed by the lower parts of the human body, together with its lower limbs, below the 4th thoracic segment. Having reached the medulla oblongata, the beam begins to contact with its own nuclear cells.	Muscles supply "instructions" to both bundles. The first neurons of the above tracks lie in certain spinal nodes. They move to the nuclei of the medulla oblongata. Two tubercles are the second neurons of the corresponding bundles. Their axons, when moving, reach the opposite side. There they form a sensitive decussation, and then move to the thalamus, already being integral part medial loop. The fibers of these bundles come into direct contact with the thalamus cells. The processes of these neurons are sent directly to the brain.
9	wedge-shaped bundle	It is formed from fibers that initiate movement in the cells of the spinal nodes, and end in the sphenoid tubercle.

Descending pathways

All descending tracts of the spinal cord with their detailed specifications and the course of movement are clearly demonstrated in table No. 2.

No. p / p	View of the descending path	Characteristics
1	Lateral corticospinal, also called lateral corticospinal or basic crossed pyramidal.	The composition of this pathway includes a large proportion of the fibers of the pyramidal system. The lateral path is localized in the lateral funiculus. Along the way, the fibers gradually become thinner. Lateral fibers conduct signals that cause conscious actions of a person.	Lateral fibers conduct signals that cause conscious actions of a person.
2	Anterior corticospinal, otherwise called corticospinal, as well as straight or uncrossed pyramidal.	This path lies in the anterior spinal cord. Like the lateral pyramidal tract, the direct pyramidal tract includes cell axons of the hemispheric motor cortex, although they are located ipsilaterally here. Initially, these axons descend to their "own" segment. After that, as part of the anterior spinal commissure, they cross over to the opposite side, ending in the mononeurons of the anterior horn.
3	Red nuclear-spinal or rubrospinal.	Starting in the red nucleus of the spinal cord, this tract subsequently descends to the motor nerve cells of the anterior horns. This pathway is responsible for the transmission of unconscious motor signals.
4	Tire-spinal, otherwise called tectospinal.	It is localized in the anterior cord next to the anterior pyramidal tract. This tract starts on the roof of the midbrain. The mononeurons of the anterior horns are its final destination. The tectospinal tract provides reflex protective actions in response to visual and auditory stimuli.
5	Vestibulospinal, otherwise called vestibulospinal.	This path is localized in the anterior spinal cord. The vestibular nuclei of the bridge are its beginning, and the anterior spinal horns are the end. The balance of the human body is ensured precisely by the transmission of impulses of the vestibulospinal tract.
6	Reticulospinal or reticulospinal.	This pathway ensures the transmission of excitatory signals from the reticular formation to the spinal nerve cells.

To understand the neurophysiology of the pathways of the human spinal cord, you will need to briefly familiarize yourself with the structure of the spine. In its structure, the spinal cord is a little like a cylinder covered with muscle tissue from all sides. Conducting pathways control the work of internal organs, as well as all organ systems and functions performed by the body. Injuries, various injuries, other ailments of the spinal cord can in some way reduce conductivity. By the way, conduction can even stop completely due to the death of neurons. total loss conduction of spinal signals is characterized by paralysis, manifested in total absence sensation in the limbs. This is very fraught with problems with the internal organs responsible for damaging the connection of nerve cells. Thus, injuries and other ailments of the lower spinal parts are often characterized by urinary incontinence and even spontaneous defecation.

Drug treatment will consist of prescribing drugs that prevent the death of brain cells, as well as additionally increase blood flow to damaged spinal areas.
As an additional treatment that stimulates the work of neurons, as well as helping to maintain muscle tone may be assigned to conduct electrical impulses.

Surgical operations to restore spinal conduction are performed in specialized spinal clinics.

Also, if necessary, the attending physician may prescribe the use of the following folk remedies.

Apitherapy

• Apitherapy. Bee stings effectively restore the conductivity of the efferent tracts. So, the poisons of these insects, penetrating into the damaged areas, provide them with an additional blood flow. If the cause of the pathology of the spine is sciatica, a growing hernia and other similar ailments, apitherapy will be an excellent addition to traditional treatment.
• Herbal medicine. Appointed medicinal fees to normalize blood circulation and improve metabolism.
• Hirudotherapy. Thanks to the treatment with leeches, it becomes possible to eliminate congestion - the inevitable attributes of vertebral pathologies.

The resulting degenerative changes almost immediately lead to a violation of conduction and reflex activity. Dying neurons are quite difficult to recover. The disease can often develop rapidly, significantly disrupting conduction. Therefore, it is advisable to contact doctors for medical help when the first signs of pathology are detected.

Ascending (afferent) pathways originating in the spinal cord

The bodies of the first neurons - conductors of all types of sensitivity to the spinal cord - lie in the spinal nodes. The axons of the cells of the spinal ganglions as part of the posterior roots enter the spinal cord and are divided into two groups: medial, consisting of thick, more myelinated fibers, and lateral, formed by thin, less myelinated fibers.

The medial group of fibers of the posterior root is sent to the posterior funiculus of the white matter, where each fiber divides in a T-shape into ascending and descending branches. The ascending branches, following upward, come into contact with the cells of the gray matter of the spinal cord in the gelatinous substance and in the posterior horn, and some of them reach the medulla oblongata, forming thin and wedge-shaped bundles, fasciculi gracilis et cuneatus(see Fig.,,), spinal cord.

The descending branches of the fibers go down and come into contact with the cells of the gray matter of the posterior columns for six to seven underlying segments. Some of these fibers form a bundle in the thoracic and cervical sections of the spinal cord, which has the form of a comma on the cross section of the spinal cord and is located between the wedge-shaped and thin bundles; in the lumbar region - a type of medial cord; V sacral region- view of the oval bundle of the posterior funiculus adjacent to the medial surface of the thin bundle.

The lateral group of fibers of the posterior root goes to the marginal zone, and then to the posterior column of gray matter, where it comes into contact with the cells of the posterior horn located in it.

The fibers extending from the cells of the nuclei of the spinal cord go up partly along the lateral funiculus of their side, and partly pass as part of the white commissure to the opposite side of the spinal cord and also go up in the lateral funiculus.

The ascending pathways (see Fig.,,), starting in the spinal cord, include the following:

1. Posterior spinocerebellar tract, tractus spinocerebellaris dorsalis, - direct cerebellar path, conducts impulses from muscle and tendon receptors to the cerebellum. The bodies of the first neurons lie in the spinal ganglion, the bodies of the second neurons lie throughout the spinal cord in the thoracic column (thoracic nucleus) of the posterior horn. The long processes of the second neurons go outward; reaching the posterior part of the spinal cord of the same side, they wrap up and rise along the lateral funiculus of the spinal cord, and then follow the lower cerebellar pedicle to the cortex of the cerebellar vermis.
2. Anterior spinocerebellar tract, tractus spinocerebellaris ventralis, conducts impulses from muscle and tendon receptors to the cerebellum. The bodies of the first neurons lie in the spinal ganglion, and the second neurons lie in the medial nucleus of the intermediate zone and send part of their fibers through the white commissure to the lateral cords of the opposite side, and part to the lateral cords of their side. These fibers reach the anterolateral parts of the lateral cords, located anterior to the posterior spinal cerebellar tract. Here, the fibers are wrapped up, go along the spinal cord, and then along the medulla oblongata and, having passed the bridge, along the upper cerebellar peduncles, having made the second decussation, they reach the cerebellar vermis.
3. Spinal tract, tractus spinoolivaris, originates from the cells of the posterior horns of the gray matter. The axons of these cells cross and rise near the surface of the spinal cord at the border of the lateral and anterior cords, ending in the nuclei of the olive. The fibers of this pathway carry information from skin, muscle and tendon receptors.
4. Anterior and lateral spinal thalamic pathways, tractus spinothalamici ventralis et lateralis(see Fig.), conduct impulses of pain, temperature (lateral path) and tactile ( forward path) sensitivity. The bodies of the first neurons lie in the spinal ganglia. The processes of the second neurons from the cells of the own nucleus of the posterior horn are sent through the white commissure to the anterior and lateral cords of the opposite side. Rising up, the fibers of these pathways pass into back departments medulla oblongata, pons and legs of the brain and reach the thalamus as part of spinal loop, lemniscus spinalis. The bodies of the third neurons of these pathways lie in the thalamus, and their processes are directed to the cerebral cortex as part of the central thalamic radiations through the posterior leg of the internal capsule (Fig.,).
5. Spinal reticular path, tractus spinoreticularis, make up fibers that pass as part of the spinal-thalamic pathways, do not intersect and form bilateral projections to all sections of the stem reticular formation.
6. Spinal tract, tractus spinotectalis, along with the spinal-thalamic pathway, passes in the lateral cords of the spinal cord and ends in the plate of the roof of the midbrain.
7. Thin bundle, fasciculus gracilis, And wedge-shaped bundle, fasciculus cuneatus(see Fig.), conduct impulses from muscles, joints and tactile sensitivity receptors. The bodies of the first neurons of these pathways are localized in the corresponding spinal nodes. Axons go as part of the posterior roots and, having entered the posterior columns of the spinal cord, take an upward direction, reaching the nuclei of the medulla oblongata.

A thin bundle occupies a medial position and conducts the corresponding impulses from lower extremities And lower parts trunk - below the 4th thoracic segment.

The wedge-shaped bundle is formed by fibers starting from the cells of all spinal nodes lying above the 4th thoracic segment.

Having reached the medulla oblongata, the fibers of the thin bundle come into contact with the cells of the nucleus of this bundle, which lies in the tubercle of the thin nucleus; the fibers of the wedge-shaped bundle end in the wedge-shaped tubercle. The cells of both hillocks are the bodies of the second neurons of the described pathways. Their axons are internal arcuate fibers, fibrae arcuatae internae, - go forward and up, go to the opposite side and, forming decussation of medial loops (sensitive decussation), decussatio lemniscorum medialium (decussatio sensoria), with fibers of the opposite side, are part of medial loop, lemniscus medialis.

Having reached the thalamus, these fibers come into contact with its cells - the bodies of the third pathway neurons, which send their processes through the internal capsule to the cerebral cortex.

Ascending (afferent) pathways originating in the brainstem

The medial loop, the trigeminal loop, the ascending path of the auditory analyzer, visual radiance, and thalamic radiance begin in the brain stem.

1. medial loop as a continuation of the thin and wedge-shaped bundles described earlier.

2. Trigeminal loop, lemniscus trigeminalis, formed by processes of nerve cells that make up sensitive nuclei trigeminal nerve(V pair), facial nerve(VII pair), glossopharyngeal nerve (IX pair) and vagus nerve(X pair).

The axons of afferent neurons located in the trigeminal ganglion approach the sensory nuclei of the trigeminal nerve. The axons of afferent neurons located in the node of the knee (VII pair) and in the upper and lower nodes of the IX and X pairs of nerves approach the common sensory nucleus of the other three nerves - the nucleus of the solitary pathway. In the listed nodes, the bodies of the first neurons are localized, and in the sensitive nuclei, the bodies of the second neurons of the path along which impulses are transmitted from the receptors of the head are localized.

The fibers of the trigeminal loop pass to the opposite side (some of the fibers follow on their side) and reach the thalamus, where they end in its nuclei.

The nerve cells of the thalamus are the bodies of the third neurons of the ascending pathways of the cranial nerves, the axons of which, as part of the central thalamic radiances, through the internal capsule are sent to the cerebral cortex (postcentral gyrus).

3. The ascending path of the auditory analyzer has as the first neurons cells that lie in the node of the cochlear part of the vestibulocochlear nerve. The axons of these cells approach the cells of the anterior and posterior cochlear nuclei (second neurons). The processes of the second neurons, moving to the opposite side, form a trapezoid body, and then take an upward direction and get the name lateral loop, lemniscus lateralis. These fibers end on the bodies of the third neurons of the auditory pathway, which lie in the lateral geniculate body. The processes of the third neurons form auditory radiance, radiatio acustica, which goes from the medial geniculate body through the posterior leg of the internal capsule to the middle part of the superior temporal gyrus.

4. Visual radiance, radiatio optica(see Fig.), connects the subcortical centers of vision with the cortex of the spur groove.

The structure of visual radiation includes two systems of ascending fibers:

• geniculate-cortical optic tract, which starts from the cells of the lateral geniculate body;
• cushion-cortical tract, starting from the cells of the nucleus, which lies in the pillow of the thalamus; man is underdeveloped.

The collection of these fibers is referred to as posterior thalamic radiations, radiationes thalamicae posteriores.

Rising to the cerebral cortex, both systems pass through the posterior leg of the internal capsule.

5. Thalamic radiations, radiationes thalamicae(see fig.), are formed by processes of thalamus cells and make up the final sections of the ascending pathways of the cortical direction.

The composition of the thalamic radiances includes:

• anterior thalamic radiations, radiationes thalamicae anteriores, - radially extending fibers of the white matter hemispheres. They start from the superior medial nucleus of the thalamus and go through the anterior leg of the internal capsule to the cortex of the lateral and inferior surfaces of the frontal lobe. Part of the fibers of the anterior thalamic radiations connects the anterior group of thalamic nuclei with the cortex of the medial surface frontal lobes and anterior part of the cingulate gyrus;
• central thalamic radiations, radiationes thalamicae centrales, - radial fibers connecting the ventrolateral group of the thalamic nuclei with the cortex of the pre- and postcentral gyrus, as well as with the adjacent sections of the cortex of the frontal and parietal lobes. Pass as part of the posterior leg of the internal capsule;
• lower leg of the thalamus, pedunculus thalami inferior, contains radial fibers that connect the thalamic cushion and medial geniculate bodies with areas of the temporal choir;
• posterior thalamic radiations(see earlier).

Relate:

1) pyramidal path;

2) rubro-spinal path;

3) vestibulo-spinal path;

4) reticulo-spinal path;

5) posterior longitudinal path.

The pyramidal path originates from giant and large pyramidal cells (Beda cells) located in the fifth layer of the cerebral cortex, mainly in the region of the anterior central gyrus. The axons of these cells (pyramidal path) go down through the anterior sections of the posterior thigh of the internal capsule, through the base of the brain stem, where they cross at the border between the medulla oblongata and the spinal cord. This crossover is incomplete. A smaller part of the fibers does not cross and is directed to the anterior column of the spinal cord called the direct pyramidal bundle.

Most of the pyramidal fibers pass to the opposite side and make up the lateral pyramidal bundle, which occupies the dorsal part of the lateral column, closer to the posterior horn. At the level of each segment of the spinal cord, the fibers of the pyramidal bundles, both direct and lateral, end in the cells of the anterior horns of the spinal cord. The fibers of the direct pyramidal bundle send impulses mainly to the muscles of the trunk, in particular chest, receiving impulses through straight and intersecting pyramidal fibers.

Thus, the entire motor path from the motor analyzer in the cerebral cortex to the muscle is represented by two neurons: the central motor neuron, or the pyramidal pathway, and the peripheral motor neuron - the cells of the anterior horns of the spinal cord with their axons - the anterior roots, the motor portion of the peripheral nerves.

The peripheral motor neuron is the final executive pathway through which all skeletal muscle movements are carried out. From whatever level of central nervous system no motor impulses come out, they cannot bypass the peripheral motor neuron. The central motor neuron, or pyramidal pathway, is an accessory, or intercalary, neuron between the motor analyzer of the cortex and the peripheral motor neuron. It is a conductor of voluntary movements and, at the same time, one of the systems through which the inhibitory effect of the cerebral cortex is transmitted to the reflex-segmental spinal mechanisms.

The rubrospinal tract of Monakov begins in the red nuclei located in the tegmentum of the midbrain. Upon exiting the red nuclei, the fibers cross over and then pass through the pons and the medulla oblongata into the spinal cord. In the spinal cord, the rubro-spinal path lies in the lateral column - in front of the pyramidal bundle and ends in the cells of the anterior horns of the spinal cord. Impulses from the subcortical nodes and the cerebellum are carried along this bundle to the final executive-motor apparatus.

The vestibulo-spinal pathway begins in the brainstem, in the vestibular nucleus of Deiters. From here it goes to the spinal cord, located in its anterior column and ending in the cells of the anterior horns. Through this conductor, impulses from the vestibular apparatus and the cerebellar vermis pass to the peripheral motor neuron.

The reticulo-spinal pathway originates in the cells of the reticular formation of the hindbrain. In the spinal cord, it is located in scattered bundles in the lateral and anterior columns. This path connects the final executive-motor apparatus with the complex reflex center of the brain stem and subcortical nodes.

The posterior longitudinal bundle connects various levels brain stem (oculomotor nuclei, vestibular apparatus) with the spinal cord, with its executive-motor apparatus. The posterior longitudinal bundle is located in the anterior column of the spinal cord, mainly in its cervical region.

Semiotics and topical diagnosis of lesions of the motor pathway. The defeat of the central and peripheral motor neuron causes movement disorders in the form of paralysis or paresis. Damage to a peripheral motor neuron causes peripheral or flaccid paralysis, damage to the central motor neuron - central or spastic paralysis.

Peripheral paralysis occurs when the cells of either the anterior horns, or the anterior roots, or peripheral nerves are damaged. In all these cases, movement disorder (paralysis) is accompanied by the disappearance of reflexes - and reflection due to the loss of the efferent part of the reflex arc, closing at the level of the lesion, a decrease or even complete disappearance of muscle tone - atony - due to the loss of the myotatic reflex, and after a certain time, the death of the muscles of the corresponding innervation zones - atrophy.

If it is necessary to determine in which part of the peripheral motor neuron the lesion occurs (cells, roots, peripheral nerves), the following signs should be followed. With damage to the cells of the anterior horns, muscle atrophy occurs early (within a month). The reaction of muscle degeneration is detected just as early. In the affected muscles, especially in chronically occurring processes that cause irritation of the cells of the anterior horns, rapid undulating contractions of individual muscle fibers are observed - fibrillar twitches. The work of a muscle or group of muscles innervated by the affected segments is disrupted. One of the criteria for damage to the cells of the anterior horns is the possibility of partial (partial) damage to the muscle. There are no sensory disturbances. The defeat of the anterior horns is often combined with the defeat of the lateral ones.

Known topico-diagnostic value is familiarity with the topographic distribution of cell groups in the anterior horns in relation to the innervation of individual muscle groups. For example, the innervation of the fingers is carried out by cells that occupy the outer and rear parts of the anterior horn. Cells central department the anterior horn is innervated by the muscles of the shoulder and pelvic girdle. Physiological studies of recent times have also revealed the functional heterogeneity of individual groups of motoneurons.

With the defeat of the anterior roots, the distribution of paralysis is also segmental. Larger so-called fascicular twitches are observed in the affected muscles. It should also be borne in mind that isolated lesions of the anterior roots are rare. More often it is combined with damage to the posterior roots.

When peripheral nerves are involved in the process, movement disorders are almost always combined with sensory ones. The latter are manifested by pain, pain symptoms of nerve tension, pain during palpation of the nerve trunks. Finally, the distribution of movement disorders is not segmental, but corresponds to the zone of innervation of a nerve or group of nerves.

Central spastic paralysis is caused by damage to the central motor neuron - the pyramidal pathway. With this form of paralysis, voluntary movements drop out below the lesion with simultaneous disinhibition of all underlying spinal reflex mechanisms. The latter is manifested by an increase tendon reflexes- hyperreflexia, increased muscle tone - hypertension, pathological reflexes. Degenerative muscle atrophy does not develop.

Sometimes, even with central paralysis, as a result of prolonged inactivity of the muscles, and the trophic disorders that occur in them, there is a slight diffuse weight loss of the muscles, which, however, is never accompanied by a degeneration reaction. Damage to the pyramidal tracts in the spinal cord (below their decussation) causes these disorders on the side of the lesion. The defeat of the pyramidal pathways in the brain (above the place of decussation in the medulla oblongata) causes central paralysis on the opposite side.

Thus, characteristic of central or spastic paralysis are: a conductive type of lesion, hyperreflexia in combination with pathological reflexes, hypertension and absence, atrophy.

Movement Research Methodology. The patient is examined active movements, their volume, pace, passive movements and muscle tone, muscle strength, muscle condition,

Active movements are checked in such a way that the subject makes movements in all large and small joints. In this case, the pace and volume of movement are recorded. Muscle tone is examined simultaneously with passive movements. A change in muscle tone is recorded taking into account the nature and degree of the altered tone and its distribution over various muscle groups. Muscle strength is tested. The strength of the brush is determined by the dynamometer. The condition of the muscles (atrophy, fibrillar and fascicular twitches) is being examined. To determine the degree of muscle weight loss, limbs are measured at symmetrical places. The electrical excitability of the affected muscles is investigated.

With peripheral paralysis, muscle atrophy is accompanied by a degeneration reaction or a degeneration reaction, which is established by examining the electrical excitability of the muscle. Normally, the active cathode causes muscle contraction at a lower current strength than the anode. This finds expression in the formula GLC>AZS (cathode - circuit - reduction is greater than the anode - circuit - reduction). During denervation of the muscle, a reaction of degeneration is revealed, which is determined by the perversion of the poles and is characterized by the formula ACS more than GLC. The complete reaction of degeneration usually occurs on the 15-20th day after denervation of the muscle. For a more subtle study of the functional state of the neuromuscular apparatus, in some cases, they resort to chronaximetry, which takes into account not only the current strength, but also the time (chronaxy) required to cause a minimum contraction. Normally, the chronaxy of various muscles is 0.001-0.01 seconds. At peripheral paralysis the chronaxy of the affected muscles is lengthened (from 0.006 to 0.05 seconds). With central paralysis, there is usually a more significant than normal discrepancy in the chronaxy numbers in the flexors and extensors of the arms and a decrease in the difference in the numbers on the legs.

At muscle atrophy caused by prolonged muscle inactivity due to, for example, diseases of the joints, prolonged immobilization of the limb, as well as diseases of the muscular apparatus, for example, with progressive muscular dystrophy, only a quantitative change in electrical excitability is observed. Qualitative changes (the reaction of rebirth) do not occur.

Recently, a more subtle and more advanced method has been introduced into the clinic. functional research muscles - electromyographic, which is based on the study of biocurrents that occur in the muscle with each impulse coming from a peripheral motor neuron.

If it is necessary to identify mild degrees of muscle weakness, which is not accompanied by pronounced changes in reflexes, tone and movements, you can use the Barre test.

If the patient, lying on his stomach, actively or passively bends his knees, it is better at an obtuse angle, then on the side pyramidal insufficiency the lower leg flexes faster. The same symptom for the arms: when stretching the arms forward, the paretic arm descends faster.

The isolated defeat of other descending ways meets seldom. Turning them off with simultaneous damage to the pyramidal tracts is covered by the resulting spastic paralysis. Therefore, the local diagnostic value of the defeat of these pathways is small.

Ascending pathways of the spinal cord

Medial lemniscal pathways formed by two ascending tracts: 1) a thin bundle of Gaulle; 2) wedge-shaped bundle of Burdakh (Fig. 4.14).

The afferent fibers of these pathways transmit information from tactile receptors in the skin and proprioceptors, in particular articular receptors. They enter the gray matter of the posterior horns of the spinal cord, should not be interrupted and pass in the posterior cords to the thin and sphenoid nuclei (Gaulle and Burdakh), where information is transmitted to the second neuron. The axons of these neurons cross, cross to the opposite side and, as part of the medial loop, rise to the specific switching nuclei of the thalamus, where they switch to third neurons, the axons of which transmit information to the posterior central gyrus, which ensures the formation of tactile sensation, sensation of body position, passive movements, vibrations.

Spinocerebral pathways they also have 2 tracts: 1) posterior Flexig and 2) anterior Govers. their afferent fibers transmit information from the proprioreceptors of muscles, tendons, ligaments, and tactile pressure receptors on the skin. They are characterized by switching to the second neuron in the gray matter of the spinal cord and moving to the opposite side. Then they pass in the lateral funiculi of the spinal cord and carry information to the cerebellar cortex.

spinothalamic pathway(lateral, anterior), their afferent fibers transmit information from skin receptors - cold, heat, pain, tactile - about gross deformation and pressure on the skin. They switch to the second neuron in the gray matter of the posterior horns of the spinal cord, pass to the opposite side and rise in the lateral and anterior cords to the thalamic nuclei, where they switch to third neurons that transmit information to the posterior central gyrus.

RICE. 4.14.

Descending pathways of the spinal cord

Receiving information from the ascending conducting system about the state of activity of the effector organs, the brain sends impulses ("instructions") through the descending conductors to the working organs, among which the spinal cord is located, and performs the leading-executive role. This happens with the help of the following systems (Fig. 4.15).

Cortinospinal or pyramidal tracts(ventral, lateral) pass through the medulla oblongata, where most intersect at the level of the pyramids, and are called pyramidal. They carry information from the motor centers of the motor zone of the cerebral cortex to the motor centers of the spinal cord, due to which voluntary movements are carried out. The ventral corticospinal tract runs in the anterior cords of the spinal cord, and the lateral one in the lateral ones.

Rubrospinal path- its fibers are axons of the neurons of the red nucleus of the midbrain, cross and go as part of the lateral cords of the spinal cord and transmit information from the red nuclei to the lateral interneurons of the spinal cord.

Stimulation of the red nuclei leads to the activation of motor neurons in flexors and inhibition of motor neurons in extensors.

Medial retinulospinal path (pontoretiiulospinal) starts from the nuclei of the pons, goes to the anterior cords of the spinal cord and transmits information to the ventromedial parts of the spinal cord. Stimulation of the pontine nuclei leads to the activation of motor neurons in both flexors and extensors with a predominant effect on the activation of motor neurons in extensors.

Lateral retinulospinal tract (tinulospinal medulore) starts from the reticular formation of the medulla oblongata, goes to the anterior cords of the spinal cord and transmits information to the interneurons of the spinal cord. Stimulation of it causes a general inhibitory effect, mainly on the motor neurons of the extensors.

vestibulospinal pathway starts from the nuclei of Deiters, goes in the anterior cords of the spinal cord, transmits information to interneurons and motor neurons from the same side. Stimulation of Deiters nuclei leads to activation of motor neurons in extensors and inhibition of motor neurons in flexors.

RICE. 4.15.

RICE. 4.16.

Tectospinal pathway starts from the superior colliculus to the quadrigemina and transmits information to motor neurons cervical spinal cord, provides regulation of functions neck muscles. The topography of the conducting tracts of the spinal cord is shown in fig. 4.16.

reflex function of the spinal cord lies in the fact that it contains the centers of reflexes. The alpha motor neurons of the anterior horns make up the motor centers of the skeletal muscles of the trunk, limbs, and the diaphragm, while the β motor neurons are tonic, maintain tension and a certain length of these muscles. Motoneurons of the thoracic and cervical (CIII-CIV) segments that innervate the respiratory muscles constitute the "spinal respiratory center". In the lateral horns of the thoracolumbar section of the spinal cord, the bodies of sympathetic neurons are laid, and in the sacral section - parasympathetic. These neurons constitute the centers of autonomic functions: vasomotor, regulation of cardiac activity (TI-TV), pupil dilation reflex (TI-TII), sweat secretion, heat generation, regulation of smooth muscle contraction of the pelvic organs (in the lumbosacral region).

Experimentally, the reflex function of the spinal cord is investigated after its isolation from the regions of the brain located above. To maintain breathing due to the diaphragm, cutting is carried out between the V and VI cervical segments. Immediately after transection, all functions are suppressed. There is a state of areflexia, which is called spinal shock.

white matter The spinal cord surrounds the gray matter and forms the columns of the spinal cord. Distinguish front, rear and side pillars. Pillars are tracts of the spinal cord formed by long axons of neurons that go up towards the brain (ascending paths) or down from the brain to the lower segments of the spinal cord (descending paths).
The ascending pathways of the spinal cord carry information from receptors in the muscles, tendons, ligaments, joints, and skin to the brain. Ascending paths are also conductors of temperature and pain sensitivity. All ascending pathways cross at the level of the spinal (or brain) cord. Thus, left half brain (cortex and cerebellum) receive information from the receptors of the right half of the body and vice versa.

The main ascending pathways: from mechanoreceptors of the skin and receptors of the musculoskeletal system are muscles, tendons, ligaments, joints - Gaulle's and Burdach's bundles, or, respectively, the gentle and wedge-shaped bundles are represented by the posterior columns of the spinal cord (Fig. 17 A).
From these receptors, information enters the cerebellum along two pathways represented by the lateral columns, which are called the anterior and posterior spinal tracts. In addition, two more paths pass in the lateral columns - these are the lateral and anterior spinal thalamic paths, which transmit information from temperature and pain sensitivity receptors.
The posterior columns provide faster information about the localization of irritations than the lateral and anterior spinal thalamic pathways.
Descending paths, passing through the anterior and lateral columns of the spinal cord, are motor, as they affect functional state skeletal muscles of the body. The pyramidal path begins mainly in the motor cortex of the hemispheres and passes through the medulla oblongata, where most of the fibers cross and pass to the opposite side. After that, the pyramidal path is divided into lateral and anterior bundles: respectively, the anterior and lateral pyramidal paths. Most of the pyramidal tract fibers terminate on interneurons, and about 20% form synapses on motor neurons. The pyramidal influence is exciting.
The reticulospinal tract, the rubrospinal tract, and the vestibulospinal tract (extrapyramidal system) start, respectively, from the nuclei of the reticular formation, the brain stem, the red nuclei of the midbrain, and the vestibular nuclei of the medulla oblongata. These pathways run in the lateral columns of the spinal cord, are involved in the coordination of movements and the provision of muscle tone. Extrapyramidal paths, as well as pyramidal ones, are crossed (Fig. 17 B).
Thus, the spinal cord carries out two essential functions: reflex and conductive. The reflex function is carried out due to the motor centers of the spinal cord: motor neurons

Dnathymia ivranya system
1

A

Rice. 17 A-B

A - Ascending pathways of the spinal cord:

1. - Gaulle's bundle;
2. - Burdakh's bundle;
3. - dorsal spinal cerebellar tract;
4. - ventral spinal cerebellar tract;
5. - anterior spinal thalamic pathway;
6. - lateral dorsal-thalamic pathway.

B - Main descending spinal tracts:
pyramidal (lateral and anterior corticospinal tracts) and extrapyramidal (rubrospinal, reticulospinal and vestibulospinal tracts) systems.

And to the flexor muscles to the flexor muscles
and extensors and extensors

A - arcs of the flexion and cross extensor reflexes; B - an elementary scheme of an unconditioned reflex. Nerve impulses that occur when the receptor (P) is stimulated go along afferent fibers (aff. nerve, one such fiber is shown) to the spinal cord (1), where they are transmitted through the intercalary neuron to efferent fibers (eff. nerve), through which they reach effector. Dashed lines - the spread of excitation from the lower parts of the central nervous system to its higher parts (2, 3, 4) up to the cerebral cortex (5) inclusive. The resulting change in the state of the higher parts of the brain, in turn, affects (see arrows) on the efferent neuron, affecting final result reflex response.

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Rice. 19. Scheme of the pathways of the spinal cord:
Descending paths:
A - pyramidal or corticospinal;
B - extrapyramidal system
Rubrospinal and reticulospinal paths, which are part of the multineuronal extrapyramidal path, which goes from the cerebral cortex to the spinal cord;
Ascending pathways: B - anterior spinal thalamic tract
Along this path, information from pressure and touch receptors, as well as from pain and temperature receptors, enters the somatosensory cortex;
D - lateral spinal-thalamic tract This way information from pain and temperature receptors comes to vast areas of the cerebral cortex.

5

1. - motor cortex;
2. - midbrain;
3. - pyramidal path;
4. - medulla;
5. - lateral corticospinal tract;
6. - anterior corticospinal tract;
7. - diffuse projections on the cortex;
8. - interlamellar nuclei of the thalamus;
9. - lateral dorsal-thalamic pathway;
10. - somatosensory cortex;
11. - ventrobasal complex of the thalamus;
12. - medial loop;
13. - red core;
14. - bridge;
15. - reticular formation;
16. - rubrospinal path;
17. - reticulospinal path;
18. - spinal cord.

Dnathmia itpginH system
their horns provide the work of the skeletal muscles of the body. At the same time, maintaining muscle tone, coordinating the work of the flexor-extensor muscles underlying movements, and maintaining the constancy of the posture of the body and its parts (see Fig. 18, p. 39). Motor neurons located in the lateral horns of the thoracic segments of the spinal cord provide respiratory movements(inhale-exhale), regulating the work of the intercostal muscles. Motoneurons of the lateral horns of the lumbar and sacral segments represent the motor centers of smooth muscles that make up the internal organs. These are the centers of urination, defecation, and the work of the genital organs.
The conduction function is performed by the spinal tracts (see Fig. 19, pp. 40 - 41).