Wedge-shaped cords. Spinal cord. The spinal cord (medulla spinalis) is located in the spinal canal. Interesting facts about white matter

- (f. anterior) see Anterior funiculus... Large medical dictionary

anterior cord Large medical dictionary

Anterior cord- (funiculus anterior, PNA, BNA; fasciculus ventralis, JNA; anterior synonymous cord of the spinal cord) a paired bundle of nerve fibers located in the white matter of the spinal cord between the anterior median fissure and the anterior lateral sulcus; contains... ... 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

spinal cord- (medulla spinalis) department of the central nervous system, from the point of view of evolution, its most ancient part, which has preserved its segmental structure. It is a white cord 40-45 cm long, located in the spinal canal (from the large... ... Glossary of terms and concepts on human anatomy

Pyramid system- a system of efferent neurons, the bodies of which are located in the cerebral cortex, ending in the motor nuclei of the cranial nerves and the gray matter of the spinal cord. As part of the pyramidal tract (tractus pyramidalis), cortical nuclear fibers are distinguished... ... Medical encyclopedia

lateral groove anterior Large medical dictionary

Lateral sulcus anterior- (sulcus lateralis anterior, PNA, BNA; sulcus lateralis ventralis, JNA) a paired longitudinal depression on the anterior surface of the spinal cord and medulla oblongata, limiting the outer side of the anterior cord of the spinal cord and the pyramid; place… … Medical encyclopedia

tegnospinal tract Large medical dictionary

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

Spinal cord- (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 thickenings and almost round in other sections. In the spinal canal... ... Medical encyclopedia

These grooves divide each half of the white matter of the spinal cord into three longitudinal cords: anterior - funiculus anterior, lateral - funiculus lateralis And posterior - funiculus posterior. The posterior cord in the cervical and upper thoracic regions is further divided intermediate groove, sulcus intermedius posterior, on two bundles: fasciculus gracilis and fasciculus cuneatu s. Both of these bundles, under the same names, pass at the top to the posterior side of the medulla oblongata.

On both sides, the spinal nerve roots emerge from the spinal cord in two longitudinal rows. Anterior root, radix ventral is s. anterior, exiting through sulcus anterolateralis, consists of neurites of motor (centrifugal, or efferent) neurons, the cell bodies of which lie in the spinal cord, whereas posterior root, radix dorsalis s. posterior included in sulcus posterolateralis, contains processes of sensitive (centripetal, or afferent) neurons, the bodies of which lie in spinal nodes.

At some distance from the spinal cord, the motor root is adjacent to the sensory root and together they form spinal nerve trunk, truncus n. spinalis, which neurologists identify under the name funiculus. When the cord is inflamed (funiculitis), segmental disorders of both the motor and sensory spheres occur; in case of root disease (radiculitis), segmental disorders of one sphere are observed - either sensory or motor, and in case of inflammation of the branches of the nerve (neuritis), the disorders correspond to the zone of distribution of this nerve. The nerve trunk is usually very short, since upon exiting the intervertebral foramen the nerve splits into its main branches.

In the intervertebral foramina near the junction of both roots, the dorsal root has a thickening - spinal ganglion, containing false unipolar nerve cells (afferent neurons) with one process, which is then divided into two branches: one of them, the central one, goes as part of the dorsal root into the spinal cord, the other, peripheral, continues into the spinal nerve. Thus, there are no synapses in the spinal ganglia, since only the cell bodies of afferent neurons lie here. This distinguishes the named nodes from the autonomic nodes of the peripheral nervous system, since in the latter intercalary and efferent neurons come into contact. Spinal nodes sacral roots lie inside the sacral canal, and coccygeal root node- inside the sac of the spinal cord.

Due to the fact that the spinal cord is shorter than the spinal canal, the exit site of the nerve roots does not correspond to the level of the intervertebral foramina. To get to the latter, the roots are directed not only to the sides of the brain, but also downwards, and the more vertically they extend from the spinal cord, the more vertical they are. In the lumbar part of the latter nerve roots descend to the corresponding intervertebral foramina in parallel filum terminate, clothing her and conus medullaris a thick bunch, which is called horse tail, cauda equina.

Structure of the spinal cord

Spinal cord, medulla spinalis (Greek myelos), lies in the spinal canal and in adults is a long (45 cm in men and 41-42 cm in women), somewhat flattened from front to back cylindrical cord, which at the top (cranially) directly passes into the medulla oblongata , and below (caudally) ends in a conical point, conus medullaris, at the level of the II lumbar vertebra. Knowledge of this fact is of practical importance (in order not to damage the spinal cord during a lumbar puncture for the purpose of taking cerebrospinal fluid or for the purpose of spinal anesthesia, it is necessary to insert a syringe needle between the spinous processes of the III and IV lumbar vertebrae).

From the conus medullaris the so-called terminal filament , filum terminale, representing the atrophied lower part of the spinal cord, which below consists of a continuation of the membranes of the spinal cord and is attached to the II coccygeal vertebra.

The spinal cord along its length has two thickenings corresponding to the nerve roots of the upper and lower extremities: the upper one is called cervical thickening , intumescentia cervicalis, and the lower - lumbosacral , intumescentia lumbosacralis. Of these thickenings, the lumbosacral one is more extensive, but the cervical one is more differentiated, which is associated with a more complex innervation of the hand as an organ of labor. Formed due to thickening of the lateral walls of the spinal tube and passing along the midline anterior and posterior longitudinal grooves : deep fissura mediana anterior, and superficial, sulcus medianus posterior, the spinal cord is divided into two symmetrical halves - right and left; each of them, in turn, has a weakly defined longitudinal groove running along the line of entry of the posterior roots (sulcus posterolateralis) and along the line of exit of the anterior roots (sulcus anterolateralis).

These grooves divide each half of the white matter of the spinal cord into three longitudinal cords: front - funiculus anterior, side - funiculus lateralis and rear - funiculus posterior. The posterior cord in the cervical and upper thoracic regions is further divided by the intermediate groove, sulcus intermedius posterior, into two bundles: fasciculus gracilis and fasciculus cuneatus . Both of these bundles, under the same names, pass at the top to the posterior side of the medulla oblongata.

On both sides, the spinal nerve roots emerge from the spinal cord in two longitudinal rows. Anterior root , radix ventral is s. anterior, exiting through the sulcus anterolateralis, consists of neurites motor (centrifugal, or efferent) neurons, whose cell bodies lie in the spinal cord, while dorsal root , radix dorsalis s. posterior, included in the sulcus posterolateralis, contains processes sensitive (centripetal, or afferent) neurons, whose bodies lie in the spinal ganglia.

At some distance from the spinal cord, the motor root is adjacent to the sensory and they together form the trunk of the spinal nerve, truncus n. spinalis, which neurologists distinguish under the name cord, funiculus. When the cord is inflamed (funiculitis), segmental disorders of both motor and sensory function occur.

spheres; in case of root disease (radiculitis), segmental disorders of one sphere are observed - either sensory or motor, and in case of inflammation of the branches of the nerve (neuritis), the disorders correspond to the zone of distribution of this nerve. The nerve trunk is usually very short, since upon exiting the intervertebral foramen the nerve splits into its main branches.

In the intervertebral foramina near the junction of both roots, the dorsal root has a thickening - spinal ganglion , ganglion spinale, containing false unipolar nerve cells (afferent neurons) with one process, which is then divided into two branches: one of them, the central one, goes as part of the dorsal root into the spinal cord, the other, peripheral, continues into the spinal nerve. Thus, there are no synapses in the spinal ganglia, since only the cell bodies of afferent neurons lie here. This distinguishes the named nodes from the autonomic nodes of the peripheral nervous system, since in the latter intercalary and efferent neurons come into contact. The spinal nodes of the sacral roots lie inside the sacral canal, and the node of the coccygeal root lies inside the sac of the dura mater of the spinal cord.

Due to the fact that the spinal cord is shorter than the spinal canal, the exit site of the nerve roots does not correspond to the level of the intervertebral foramina. To get to the latter, the roots are directed not only to the sides of the brain, but also downwards, and the more vertically they extend from the spinal cord, the more vertical they are. In the lumbar part of the latter, the nerve roots descend to the corresponding intervertebral foramina parallel to the filum terminate, covering it and the conus medullaris with a thick bundle, which is called ponytail , cauda equina.

Fresh sections of the brain show that some structures are darker—the gray matter of the nervous system—and other structures are lighter—the white matter of the nervous system. The white matter of the nervous system is formed by myelinated nerve fibers, the gray matter by the unmyelinated parts of the neuron - somas and dendrites.

The white matter of the nervous system is represented by central tracts and peripheral nerves. The function of white matter is to transmit information from receptors to the central nervous system and from one part of the nervous system to another.

In the white matter immediately adjacent to the apex of the posterior horn, a border zone is distinguished.

White matter, substantia alba, as noted, is localized around the gray matter, along the periphery of the spinal cord. The white matter of one half of the spinal cord is connected to the white matter of the other half by a very thin white commissure, commissura alba, running transversely in front of the central canal.

The spinal cord grooves divide the white matter of each half into three cords. The anterior funiculus, funiculus ventralis, is located between the anterior median fissure and the anterior lateral groove. The posterior funiculus, funiculus dorsalis, is located between the posterior median and posterior lateral grooves. The lateral funiculus, funiculus lateralis, is located between the anterolateral and posterolateral grooves.

The white matter of the spinal cord is represented by processes of nerve cells that have myelin sheaths. The combination of these processes in the spinal cord cords form three systems of spinal cord pathways.

1. Own associative bundles (anterior, lateral and posterior), which provide connections between segments at different levels within the spinal cord (belong to the segmental apparatus). As a result, irritation coming from a certain area of the body is transmitted not only to the corresponding segment of the spinal cord, but also affects other segments. As a result, a simple reflex can involve an entire group of muscles in the response, providing complex coordinated movement.

2. Ascending (afferent, sensory) bundles heading to the centers of the brain and cerebellum.

3. Descending (efferent, motor) pathways going from the brain to the cells of the anterior horns of the spinal cord.

The last two systems of bundles form a new young suprasegmental conduction apparatus of bilateral connections of the spinal cord and brain. It arose only when the brain appeared. And as the brain developed, the spinal cord pathways grew outward from the gray matter, forming its white matter. This explains the fact that the white matter surrounds the gray matter on all sides.

In the white matter of the anterior cords there are predominantly descending pathways, in the lateral cords there are both ascending and descending pathways, and in the posterior cords there are ascending pathways.

The anterior funiculus, funiculus ventralis, includes the following pathways:

1. Anterior corticospinal (pyramidal) tract, tractus corticospinalis anterior (pyramidalis) – motor, located near the anterior median fissure, occupies the medial sections of the anterior cord. Transmits impulses of motor reactions from the cerebral cortex to the anterior horns of the spinal cord.

2. The reticular-spinal tract, tractus reticulospinalis, conducts impulses from the reticular formation of the brain to the motor nuclei of the anterior horns of the spinal cord. It is located in the central part of the anterior funiculus, lateral to the pyramidal tract. Participates in the regulation of muscle tone.

3. The tegnospinal tract, tractus tectospinalis, located anterior to the pyramidal tract, connects the subcortical centers of vision (superior colliculi) and hearing (inferior colliculi) with the motor nuclei of the anterior horns of the spinal cord. The presence of this tract allows for reflexive defensive reactions to sudden visual and auditory stimuli.

4. The anterior spinothalamic tract, tractus spinothalamicus anterior, is located slightly anterior to the reticulospinal tract. Conducts impulses of tactile sensitivity (touch and pressure).

5. The vestibulospinal tract, tractus vestibulospinalis, is located in the anterior sections of the anterior cord and extends to the border of the anterior cord with the lateral cord, i.e. to the anterolateral groove. The fibers of this pathway go from the vestibular nuclei of the VIII pair of cranial nerves, located in the medulla oblongata, to the motor neurons of the anterior horns of the spinal cord. Participates in maintaining body balance.

6. The posterior longitudinal fasciculus, fasciculus longitudinalis dorsalis, stretches from the brain stem to the upper segments of the spinal cord. Conducts nerve impulses that coordinate the work of the muscles of the eyeball and the muscles of the neck, resulting in a friendly rotation of the head and eyes in the desired direction.

The lateral cord, funiculus lateralis, contains the following pathways:

1. The posterior spinocerebellar tract, tractus spinocerebellaris posterior, (Flexig's bundle), conducts impulses of proprioceptive sensitivity.

2. The anterior spinocerebellar tract, tractus spinocerebellaris anterior, (Gowers bundle), also carrying unconscious proprioceptive impulses to the cerebellum (unconscious coordination of movements).

3. The lateral spinothalamic tract, tractus spinothalamicus lateralis, conducts impulses of pain and temperature sensitivity.

The descending tracts of the lateral funiculus include:

4. The lateral corticospinal tract, tractus corticospinalis lateralis (pyramidalis), conducts motor impulses from the cerebral cortex to the anterior horns of the spinal cord.

5. The red nuclear spinal tract, tractus rubrospinalis, is a conductor of impulses for automatic (subconscious) control of movements and tone of skeletal muscles.

6. Olivospinal tract, tr. olivospinalis,

The posterior cord, funiculus dorsalis, at the level of the cervical and upper thoracic segments of the spinal cord by the posterior intermediate groove, sulcus intermedius dorsalis, is divided into two bundles. The medial one is directly adjacent to the posterior median sulcus - this is a thin fascicle (Gaull's fascicle), fasciculus gracilis. Slightly more lateral is the wedge-shaped bundle, fasciculus cuneatus (Burdach's bundle).

Thin Bun consists of longer conductors running from the lower torso and lower extremities of the corresponding side to the medulla oblongata. Moreover, these conductors enter the spinal cord as part of the dorsal roots of the 19 lower segments of the spinal cord and occupy a medial position in the posterior cord.

Wedge-shaped bundle includes shorter conductors running from the upper limbs and upper torso also to the medulla oblongata. These conductors enter the spinal cord as part of the dorsal roots of the 12 upper segments of the spinal cord and occupy a lateral position in the dorsal funiculus.

Gaulle and Burdach bundles– these are conductors of conscious proprioceptive sensitivity (articular-muscular feeling) of the cortical direction. In addition, they are conductors of the cutaneous stereognostic sense. Thus, they carry information to the cerebral cortex about the position of the body and its parts in space and relative to each other.

Funiculi medullae spinalis. Three columns of white matter, separated by anterior and posterior horns of gray matter, as well as corresponding radicular filaments.
Anterior funiculus, funiculus anterior. It lies between the anterior median fissure on one side and the anterior horn and its radicular filaments on the other. Rice. A.
Lateral funiculus, funiculus lateralis. Located outside the gray matter between the anterior and posterior roots. Rice. A.
Posterior funiculus, funiculus posterior. Located between the posterior horn and its radicular filaments on one side, and the posterior median septum on the other. Rice. A.
Segments of the spinal cord, segmenta medullae spinalis. Areas of the brain whose radicular filaments form one pair of spinal nerves passing through the corresponding intervertebral foramina. On an isolated spinal cord there are no boundaries between segments.
Cervical segments - cervical part, segmenta cervicalia l - 57 - pars cervicalis. The radicular filaments of segments 1-7 emerge from the spinal canal above the corresponding vertebra number, and the radicular filaments of the eighth segment go below the body of C 7. The cervical part of the spinal cord extends from the atlas to the middle of C 7. Fig. IN.
Thoracic segments = thoracic part, segmenta thoracica = pars thoracica. Located from the middle of C 7 to the middle of T 11. Fig. IN.
Lumbar segments - lumbar part, segmenta lumbalia - pars lumbalis. Projected from the middle of T 11 to the upper edge of the body L 1. Fig. IN.
Sacral segments - sacral part, segmenta sacralia - pars sacralia They lie behind the body L 1. Fig. IN.
Coccygeal segments - coccygeal part, segmenta coccygea - pars coccygea. Three small segments of the spinal cord. Rice. IN.
Sections of the spinal cord, sectiones medullae spinalis. Serve to describe the internal structure of the spinal cord.
Central canal, canalis centralis. Obliterated remnant of the neural tube cavity. Located inside the central intermediate substance. Rice. A, G.
Gray matter, substantia grisea. It is located medially from the white matter and consists of multipolar ganglion cells that form symmetrical solid columns connected to each other along the spinal cord. In cross sections, they correspond to the horns of gray matter, the shape and size of which vary in different parts of the spinal cord. Rice. A.
White matter, substantia alba. Formed by myelinated nerve fibers, which are grouped into pathways and are part of three cords. Rice. A.
Central gelatinous substance, substantia gelatinosa centralis. A narrow zone around the central canal, which consists of processes of ependymal cells.
Gray pillars, columnae griseae. The spinal cord consists of three columns of gray matter. Rice. B.
Anterior column, columna anterior. Consists mainly of motor neurons. Rice. B.
Anterior horn, cornu anterius. Corresponds to the front pillar. Rice. G.
Anterolateral nucleus, nucleus anterolateralis. Located in the anterolateral section of the anterior horn of the fourth - eighth cervical (C4 - 8) and second lumbar - first sacral (L2 - S1) segments of the spinal cord. The neurons of this nucleus innervate the muscles of the limbs. Rice. G.
Anteromedial nucleus, nucleus anteromedialis. Located in the anteromedial part of the anterior horn along the entire length of the spinal cord. Rice. G.
Posterolateral nucleus, nucleus posterolateralis. Located behind the anterolateral nucleus in the fifth cervical - first thoracic (C5 - T1) and second lumbar - second sacral (L2 - S2) segments of the spinal cord. Its neurons innervate the muscles of the limbs. Rice. G.
Posterolateral nucleus, nucleus retroposterolateralis. It lies behind the posterolateral nucleus in the eighth cervical - first thoracic (C8 - T1) and first - third sacral (S1 - 3) segments of the spinal cord. Rice. G.
Posteromedial nucleus, nucleus posteromedialis. It is located next to the white commissure along the first thoracic - third lumbar (T1 - L3) segments of the spinal cord. The neurons of this nucleus probably innervate the muscles of the trunk. Rice. G.
Central nucleus, nucleus centralis. A small group of neurons without clear boundaries in some cervical and lumbar segments. Rice. G.
The nucleus of the accessory nerve, nucleus nervi accessorii (nuc. accessorius). Located in the upper six cervical segments (C1 - b) near the anterolateral nucleus. The processes of the neurons of the nucleus form the spinal part of the accessory nerve. Rice. G.
Nucleus of the phrenic nerve, nucleus nervi phrenici (nuc. phrenicus). Lies in the middle of the anterior horn along the fourth - seventh cervical segments (C4 - 7). Rice. G.