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Spinal cord. The spinal cord (medulla spinalis) is located in the spinal canal

  • Date: 19.07.2019

Front cords contain the following pathways

1) anterior, motor, cortical-spinal (pyramidal) path. This pathway contains processes of pyramidal cells of the cortex of the anterior central gyrus, which end on the motor cells of the anterior horn of the opposite side, transmits impulses of motor reactions from the cortex large brain to the anterior horns of the spinal cord;

2) the anterior dorsal-thalamic pathway in the middle part of the anterior cord provides impulse conduction tactile sensitivity(touch and pressure);

3) at the border of the anterior cord with the lateral one is the vestibular-spinal pathway, originating from the vestibular nuclei of the VIII pair of cranial nerves located in the medulla oblongata, and heading to the motor cells of the anterior horns. The presence of the tract allows you to maintain balance and coordinate movements.

The lateral cords contain the following pathways:

1) the posterior spinal cord tract occupies the posterior lateral sections of the lateral cords and is a conductor of reflex proprioceptive impulses heading to the cerebellum;

2) the anterior spinal cord is located in the anterolateral parts of the lateral cords, it follows into the cerebellar cortex;

3) the lateral dorsal thalamic pathway - the pathway for conducting impulses of pain and temperature sensitivity, located in the anterior sections of the lateral cord. From the descending tracts in the lateral cords are the lateral cortical-spinal (pyramidal) path and extrapyramidal - the red-nuclear-spinal path;

4) the lateral cortical-spinal pathway is represented by fibers of the main motor pyramidal pathway (a pathway for conducting impulses that causes conscious movements), which lie medial to the posterior spinal pathway and occupy a significant part of the lateral cord, especially in the upper segments of the spinal cord;

5) the red-spinal tract is located ventral to the lateral cortical-spinal (pyramidal) tract. This pathway is a reflex motor efferent pathway.

Brain

The brain is located in the cranial cavity. The brain has a complex shape, which corresponds to the relief of the cranial vault and cranial fossa (Fig. 24, 25, 26). The superior lateral parts of the brain are convex, the base is flattened and has many irregularities. In the region of the base, 12 pairs of cranial nerves extend from the brain.

The mass of the brain in an adult ranges from 1100 to 2000 g. On average, it is equal to 1394 g in men, 1245 g in women. This difference is due to the lower body weight in women.

The brain consists of five sections: the medulla oblongata, posterior, middle, diencephalon and terminal brain.

During an external examination of the brain, the cerebral stem, consisting of the medulla oblongata, the bridge and the midbrain, is isolated (Fig. 27, 28, 29), the cerebellum and the large brain (see Fig. 24, 26). In humans, the cerebral hemispheres cover the rest of the brain in front, from above and from the sides, they are separated from each other by the longitudinal slit of the large brain. In the depths of this gap is the corpus callosum, which connects both hemispheres (see Fig. 25). The corpus callosum, like the medial surfaces of the hemispheres, can be seen only after the upper edges of the hemispheres are diluted and, accordingly, the longitudinal slit of the cerebrum is widened. In the normal state, the medial surfaces of the hemispheres are quite close to each other, in the skull they are separated only by a large sickle of the dura mater. The occipital lobes of the cerebral hemispheres are separated from the cerebellum by the transverse fissure of the cerebrum.

The surfaces of the cerebral hemispheres are lined with grooves (see Fig. 24, 25, 26). Deep primary grooves divide the hemispheres into lobes (frontal, parietal, temporal, occipital), small secondary grooves separate narrower sections - gyrus. In addition, they also distinguish between unstable and highly variable different people tertiary grooves that divide the surface of the convolutions and lobules into smaller areas.

On external examination of the brain from the side (see Fig. 24), the cerebral hemispheres are visible, the cerebellum (dorsally) and the pons (ventrally) are adjacent to them from below. Beneath them, the medulla oblongata is seen, passing downward into the spinal cord. If you bend the temporal lobe of the large brain down, then in the depths of the lateral (Sylvian) groove, you can see the smallest lobe of the large brain - the insular lobe (islet).

On the lower surface of the brain (see Fig. 26), structures are visible belonging to all five of its divisions. In the front part there are the frontal lobes protruding forward, the temporal lobes are located on the sides. In the middle part between the temporal lobes (see Fig. 26), the lower surface of the diencephalon, midbrain and medulla oblongata, passing into the spinal cord, is visible. On the sides of the pons and the medulla oblongata, the lower surface of the cerebellar hemispheres is visible.

On the lower surface (base) of the brain, the following anatomical structures are visible (see Fig. 26). In the olfactory grooves of the frontal lobes, the olfactory bulbs are located, which pass the olfactory tracts and olfactory triangles posteriorly. 15–20 olfactory filaments (olfactory nerves) - I pair of cranial nerves, fit the olfactory bulbs. Behind the olfactory triangles, on both sides, the anterior perforated substance is visible, through which blood vessels pass into the depths of the brain. Between both areas of the perforated substance is the intersection of the optic nerves (optic chiasm), which are the second pair of cranial nerves.

Behind the optic chiasm there is a gray tubercle, passing into the funnel, connected to the pituitary gland (cerebral appendage). Two mastoid bodies are located behind the gray tubercle. These formations belong to the diencephalon, its ventral part - the hypothalamus. The hypothalamus is followed by the legs of the brain (structures of the midbrain), and behind them in the form of a transverse roller is the ventral part of the hindbrain - the brain bridge. Between the legs of the brain, the inter-pectoral fossa opens, the bottom of which is perforated by vessels penetrating into the depths of the brain - the posterior perforated substance. Lying on the sides of the perforated substance, the legs of the brain connect the bridge with the cerebral hemispheres. On the inner surface of each leg of the brain, near the anterior edge of the bridge, the oculomotor nerve (III pair) emerges, and on the side of the leg of the brain - the trochlear nerve (IV pair of cranial nerves).

From the bridge posteriorly and laterally, the thick middle legs of the cerebellum diverge. From the thickness of the middle pedicle of the cerebellum, the trigeminal nerve (V pair) emerges.

The medulla oblongata is located posterior to the bridge. From the transverse groove separating the medulla oblongata from the bridge, the outflow nerve (VI pair) medially emerges, and the facial nerve (VII pair) and the vestibular vestibular nerve (VIII pair of cranial nerves) are lateral to it. On the sides of the median groove of the medulla oblongata, running longitudinally, longitudinal thickenings are visible - pyramids, and on the side of each of them are olives. From the groove behind the olive, from the medulla oblongata, successively emerge cranial nerves - glossopharyngeal (IX pair), vagus * (X pair), accessory (XI pair), and from the groove between the pyramid and the olive - the hypoglossal nerve (XII pair of cranial nerves).

Medulla

The medulla oblongata is a direct continuation of the spinal cord (see Fig. 26, 27, 28, 29). Its lower border is considered to be the exit point of the roots of the 1st cervical spinal nerve or the intersection of the pyramids, the upper border is the lower (posterior) edge of the bridge. The length of the medulla oblongata is about 25 mm, its shape resembles a truncated cone, base upward, or a bulb **.

The anterior surface of the medulla oblongata (see Fig. 26, 27) is divided by the anterior median fissure, which is a continuation of the anterior median fissure of the spinal cord. On the sides of this gap there are longitudinal ridges - pyramids. The pyramids are formed by bundles of nerve fibers of the pyramidal pathways. Fibers of the pyramidal tract connect the cerebral cortex with the nuclei of the cranial nerves and the anterior horns of the spinal cord, providing conscious movement. On the side of the pyramid, on each side, there is an olive, separated from the pyramid by an anterior lateral groove.

The posterior surface of the medulla oblongata (see Fig. 29) is divided by the posterior median groove, which is a continuation of the posterior median groove of the spinal cord. On the sides of this groove are the extensions of the posterior cords of the spinal cord, which diverge upward and pass into the lower cerebellar legs. The medial edges of these legs limit the umbo-shaped fossa, and the place of their divergence forms the lower corner of the specified fossa. Each posterior cord in the lower parts of the medulla oblongata consists of two bundles - wedge-shaped (lateral) and thin (medial), on which tubercles containing nuclei are visible near the lower corner of the rhomboid fossa: wedge-shaped (lateral) and thin (medial). In these nuclei, tactile and proprioceptive impulses are switched from the axons of sensitive pseudo-unipolar neurons to intercalary neurons. The axons of the intercalated cells subsequently move to the opposite side, forming a lemniscus (Latin "lemniscus" - a loop), and are directed to the specific nuclei of the thalamus.

The medulla oblongata is built from white and gray matter.

White matter is formed by nerve fibers that make up the corresponding pathways. The motor pathways (descending) are located in the anterior regions of the medulla oblongata, the sensitive (ascending) ones lie more dorsally.

The gray matter of the medulla oblongata is represented by the nuclei of the IX, X, XI, XII pairs of cranial nerves, the nuclei of the olives, the centers of respiration, blood circulation and the reticular formation.

The reticular formation (lat. "Formatio reticularis" - reticular formation) is a collection of cells, cell clusters (nuclei) and nerve fibers that form a network located medially in the brain stem (medulla oblongata, pons and midbrain). There is a reticular formation, although less developed, and in the spinal cord. Here it is located in the angle between the posterior and anterior horns (or lateral horns, if they are expressed in this segment).

The bodies of neurons in the reticular formation (RF) are surrounded by a mass of tangled fibers, representing the beginning and ends of the processes that go to the bodies of neurons or depart from them. Since, when viewed under a light microscope, they look like tangled fibers, this part of the gray matter was called neuropil (Latin “pilos” - felt). The axons in the neuropil are poorly myelinated, and the dendrites have no myelin sheath at all. In general, larger neurons are located medially in the reticular formation, forming long ascending and descending axons. Smaller neurons, which are mainly associative, are located laterally in the RF.

The reticular formation is associated with all the senses, motor and sensory areas of the cerebral cortex, the thalamus and hypothalamus, the spinal cord. It regulates the level of excitability and tone of various departments nervous system, including the cerebral cortex, is involved in the regulation of the level of consciousness, emotions, sleep and wakefulness, autonomic functions, and purposeful movements.

Above the medulla oblongata are the structures of the hindbrain - the pons (ventrally) and the cerebellum (dorsally).

Bridge

The bridge (Varoliev's bridge), which is a structure of the hindbrain, has the form of a transversely lying thickened ridge (see Fig. 24, 25, 26). From the lateral sides of the cerebellum to the right and left backward, deep into the cerebellum, the middle cerebellar legs extend. The posterior surface of the pons, covered by the cerebellum, participates in the formation of the rhomboid fossa. Below the bridge is the medulla oblongata, the border between them is the lower edge of the bridge. Above the bridge is the midbrain, the border between them is considered top edge bridge.

The anterior surface of the pons is transversely striated due to the transverse direction of the fibers that go from the medially lying native pons nuclei to the middle cerebellar peduncles and further to the cerebellum. On the anterior surface of the bridge along the midline, there is a longitudinal basilar groove, in which the artery of the same name lies (see Fig. 26). In the frontal section through the bridge, two parts of it are visible: the front (main, basilar) and the back (tire). The border between them is the trapezoidal body formed by transversely running fibers of the pathway of the auditory analyzer.

In the posterior part of the bridge (tire) is the reticular formation, the nuclei of the V, VI, VII, VIII pairs of cranial nerves lie, the ascending pathways pass.

The anterior (basilar) part of the bridge consists of nerve fibers that form descending pathways, among which there are cell clusters - nuclei. The pathways of the anterior (basilar) part connect the cerebral cortex with the spinal cord, with the motor nuclei of the cranial nerves and with the cerebellar cortex. Between the nerve fibers of the pathways, their own nuclei of the bridge lie.

Cerebellum

The cerebellum is a structure of the hindbrain, it is located dorsal to the pons, under the occipital poles of the cerebral hemispheres, with which it is separated by the transverse fissure of the cerebrum (see Fig. 24, 25). In the cerebellum, two convex hemispheres are distinguished and the worm is an unpaired median part (Fig. 31). The worm is the most ancient part of the cerebellum; the hemispheres were formed much later (in mammals).

The surfaces of the hemispheres and the worm are separated by transverse parallel grooves (cracks), between which are located narrow and long cerebellar gyri - the sheets of the cerebellum. Due to this, its surface in an adult is on average 850 cm2. In the cerebellum, the upper and lower surfaces are distinguished. The border between these surfaces is a deep horizontal fissure that runs along the posterior edge of the cerebellum. The horizontal fissure originates in the lateral parts of the cerebellum at the place where the middle legs enter it. Groups of sheets, separated by deep grooves, form lobules of the cerebellum. Since the grooves of the cerebellum are continuous and pass from the vermis to the hemispheres, each lobule of the vermis is connected on the right and left sides with symmetrical lobules of the cerebellar hemispheres.

In section, the cerebellum consists of gray and white matter(fig. 32). The gray matter of the cerebellum is represented by the cerebellar cortex and cerebellar nuclei. The cerebellar cortex is located on its surface, its thickness is 1–2.5 mm. The white matter and nuclei of the cerebellum are located inside the cerebellum.

Gray matter. The neurons in the cerebellar cortex are arranged in three layers: the outer layer is molecular, the middle layer is piriform neurons (ganglionic), and the inner layer is granular. The molecular and granular layers mainly contain small neurons. Large pear-shaped neurons (Purkinje cells), up to 80 microns in size (on average 60 microns), are located in the middle layer in one row. These are efferent neurons of the cerebellar cortex. The dendrites of Purkinje cells are located in the surface molecular layer, and axons are directed to the neurons of the cerebellar and thalamic nuclei. The rest of the neurons of the cerebellar cortex are intercalary (associative), they transmit impulses to piriform neurons.

In the thickness of the white matter of the cerebellum there are accumulations of gray matter - paired nuclei (see Fig. 32). In each half of the cerebellum, the core of the tent is located closest to the midline. Lateral to it is the spherical nucleus. The corky nucleus is located even more laterally. The largest and most lateral nucleus of the cerebellum, the dentate nucleus, is located within the cerebellar hemisphere.

White matter of the cerebellum. Afferent and efferent fibers connecting the cerebellum with other parts of the brain form three pairs of cerebellar peduncles (see Fig. 28). The lower legs connect the cerebellum with the medulla oblongata, the middle ones - with the bridge, the upper ones - with the structures of the middle, diencephalon and telencephalon.

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3. Pathways of the spinal cord

In the intermediate zone, the central intermediate (gray) substance is located, the processes of cells of which are involved in the formation of the spinal cord. At the level of the cervical segments of the spinal cord between the anterior and posterior horns, and at the level of the upper thoracic segments - between the lateral and posterior horns in the white matter adjacent to the gray, the reticular formation is located. The reticular formation here has the form of thin bars of gray matter, intersecting in different directions, and consists of nerve cells with large quantity processes.

Gray matter of the spinal cord with posterior and anterior roots spinal nerves and with its own bundles of white matter, bordering the gray matter, forms its own, or segmental, apparatus of the spinal cord. The main purpose of the segmental apparatus as the phylogenetically oldest part of the spinal cord is to carry out innate reactions (reflexes) in response to stimulation (internal or external). IP Pavlov defined this type of activity of the segmental apparatus of the spinal cord by the term "unconditioned reflexes".

The white matter is localized outward from the gray matter. The grooves of the spinal cord divide the white matter into three cords symmetrically located on the right and left. The anterior cord is located between the anterior median fissure and the anterior lateral groove. In the white matter, posterior to the anterior median fissure, an anterior white commissure is distinguished, which connects the anterior cords of the right and left sides. The posterior cord is located between the posterior median and posterior lateral sulci. The lateral cord is the area of ​​white matter between the anterior and posterior lateral grooves.

The white matter of the spinal cord is represented by the processes of nerve cells. The totality of these processes in the cords of the spinal cord make up three bundle systems (tracts, or pathways) of the spinal cord:

1) short bundles of associative fibers connecting spinal cord segments located at different levels;

2) ascending (afferent, sensory) bundles heading to the centers of the cerebrum and cerebellum;

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

The last two bundle systems form a new (in contrast to the phylogenetically older segmental apparatus) suprasegmental conductive apparatus of bilateral spinal cord connections. In the white matter of the anterior cords, there are mainly descending pathways, in the lateral cords - both ascending and descending pathways, in the posterior cords there are ascending pathways.

The anterior cord includes the following pathways:

1. Anterior cortical-cerebrospinal (pyramidal) pathway - motor, contains processes of giant pyramidal cells (giant pyramidal neuron). The bundle of nerve fibers that form this path lies near the anterior median fissure, occupying the anteromedial sections of the anterior cord. The pathway transmits impulses of motor reactions from the cerebral cortex to the anterior horns of the spinal cord.

2. The reticular-spinal path conducts impulses from the reticular formation of the brain to the motor nuclei of the anterior horn of the spinal cord. It is located in the central part of the anterior cord, lateral to the cortical-spinal path.

3. The anterior spinal-thalamic tract is located somewhat anterior to the reticular-spinal tract. Conducts impulses of tactile sensitivity (touch and pressure).

4. The lining-spinal path connects the subcortical centers of vision (upper mounds of the roof of the midbrain) and hearing (lower mounds) with the motor nuclei of the anterior horns of the spinal cord. It is located medial to the anterior cortical-spinal (pyramidal) pathway. The bundle of these fibers is directly adjacent to the anterior median fissure. The presence of this tract makes it possible to carry out reflex protective movements during visual and auditory stimuli.

5. Between the anterior cortical-spinal (pyramidal) pathway in front and the anterior gray commissure, the posterior longitudinal bundle is located behind. This bundle extends from the brainstem to the upper segments of the spinal cord. The fibers of this bundle conduct nerve impulses, coordinating, in particular, the work of muscles eyeball and neck muscles.

6. The vestibular spinal cord is located on the border of the anterior cord with the lateral cord. This pathway takes place in the superficial layers of the white matter of the anterior cord of the spinal cord, directly near its anterior lateral groove. The fibers of this path go from the vestibular nuclei of the VIII pair of cranial nerves, located in the medulla oblongata, to the motor cells of the anterior horns of the spinal cord.

The lateral cord of the spinal cord contains the following pathways:

1. The posterior spinal cord (Flexig's bundle), conducts impulses of proprioceptive sensitivity, occupies the posterolateral sections of the lateral cord near the posterior lateral groove. Medially, the bundle of fibers of this pathway is adjacent to the lateral cortical-spinal (pyramidal) pathway, the red-nuclear-spinal and lateral spinal-thalamic pathways. In front, the posterior spinal cord path is in contact with the anterior path of the same name.

2. The anterior spinal cord (Govers' bundle), which also carries proprioceptive impulses to the cerebellum, is located in the anterolateral sections of the lateral cord. In front, it adjoins the anterior lateral groove of the spinal cord, borders on the olivospinal pathway. Medially, the anterior cerebellar tract is adjacent to the lateral spinal thalamic and dorsal tegmental tracts.

3. The lateral spinal-thalamic pathway is localized in the anterior sections of the lateral cord, between the anterior and posterior spinal-cerebellar pathways from the lateral side, the red-spinal and vestibular-spinal pathways from the medial side. Conducts impulses of pain and temperature sensitivity.

The descending systems of the lateral cord fibers include the lateral cortical-spinal (pyramidal) and extrapyramidal red-nuclear-spinal pathways.

4. The lateral cortical-spinal (pyramidal) pathway conducts motor impulses from the cerebral cortex to the anterior horns of the spinal cord. A bundle of fibers of this path, which are the processes of giant pyramidal cells, lies medial to the posterior spinal cord and occupies a significant part of the lateral cord area, especially in the upper segments of the spinal cord. Ahead of this path is the red-nuclear-spinal pathway. In the lower segments, it occupies less and less area on the cuts.

5. The red-spinal path is located anterior to the lateral cortical-spinal (pyramidal) path. Laterally, in a narrow area, the posterior spinal-cerebellar pathway (its anterior sections) and the lateral spinal-thalamic pathway are adjacent to it. The red-spinal tract is a conductor of impulses for automatic (subconscious) control of movements and tone of skeletal muscles to the anterior horns of the spinal cord.

In the lateral cords of the spinal cord, there are also bundles of nerve fibers that form other pathways (for example, the spinal cord, olivospinal cord, etc.).

The posterior cord at the level of the cervical and upper thoracic segments of the spinal cord is divided by the posterior intermediate groove into two bundles. The medial one is directly adjacent to the posterior longitudinal groove - this is a thin bundle (Gaul's bundle). Its lateral side is adjoined from the medial side to the posterior horn by a wedge-shaped bundle (Burdakh's bundle). The thin bundle consists of longer conductors running from the lower torso and lower limbs the corresponding side to the medulla oblongata. It includes fibers that make up the posterior roots of the 19 lower segments of the spinal cord and occupy its more medial part in the posterior cord. Due to the entry into the 12 upper segments of the spinal cord fibers belonging to the neurons innervating the upper limbs and upper part trunk, a wedge-shaped bundle is formed, which occupies a lateral position in the posterior cord of the spinal cord. Thin and wedge-shaped bundles are conductors of proprioceptive sensitivity (articular-muscular feeling), which carry information to the cerebral cortex about the position of the body and its parts in space.

Topic 2. The structure of the brain

1. Means and cavities of the brain

The brain, encephalon, with the membranes surrounding it is located in the cavity brain department skull. In this regard, its convex upper lateral surface the shape corresponds to the inner concave surface of the cranial vault. The lower surface - the base of the brain - has a complex relief, corresponding to the shape of the cranial fossae of the inner base of the skull.

The brain, like the spinal cord, is surrounded by three meninges. These connective tissue sheets cover the brain, and in the region of the foramen magnum pass into the membranes of the spinal cord. The outermost of these membranes is the dura mater of the brain. It is followed by the middle - arachnoid, and inside of it is the inner soft (vascular) membrane of the brain, adjacent to the surface of the brain.

The hard shell of the brain, the shell, differs from the other two in its special density, strength, presence in its composition a large number collagen and elastic fibers. Lining the cranial cavity from the inside, the hard shell of the brain is at the same time the periosteum of the inner surface of the bones of the cerebral section of the skull. The hard shell of the brain is loosely connected to the bones of the vault (roof) of the skull and is easily separated from them.

On the inner base of the skull (in the region of the medulla oblongata), the hard shell of the brain grows together with the edges of the foramen magnum and continues into hard shell spinal cord. Inner surface hard shell, facing the side of the brain (to arachnoid), smooth.

The largest process of the dura mater of the brain is located in the sagittal plane and penetrating into the longitudinal slit of the cerebrum between the right and left hemispheres of the cerebral sickle (large sickle process). It is a thin crescent-curved plate of the hard shell, which in the form of two leaves penetrates into the longitudinal slit of the large brain. Without reaching corpus callosum, this plate separates the right and left cerebral hemispheres from each other

2. Brain mass

The mass of the adult brain ranges from 1100 to 2000 g; on average, for men it is 1394 g, for women - 1245 g. The mass and volume of the brain of an adult for 20 to 60 years remain maximum and constant for each given individual. After 60 years, the mass and volume of the brain decreases slightly.

3. Classification of parts of the brain

When examining the preparation of the brain, its three largest components are clearly visible: the cerebral hemispheres, the cerebellum and the brain stem.

Cerebral hemispheres. In an adult, it is the most highly developed, largest and most functionally important part of the central nervous system. Sections of the cerebral hemispheres cover all other parts of the brain.

The right and left hemispheres are separated from each other by a deep longitudinal fissure of the large brain, which in the depths between the hemispheres reaches the large commissure of the brain, or corpus callosum. In the posterior regions, the longitudinal slit is connected to the transverse slit of the cerebral mass, which separates the cerebral hemispheres from the cerebellum.

Deep and shallow grooves are located on the upper-lateral, medial and lower (basal) surfaces of the cerebral hemispheres. Deep grooves divide each of the hemispheres into cerebral lobes. Small grooves are separated from each other by the convolutions of the large brain.

The lower surface or base of the brain is formed by the ventral surfaces of the cerebral hemispheres, the cerebellum and the ventral parts of the brain stem most accessible here for viewing.

In the brain, five divisions are distinguished, developing from five cerebral vesicles: 1) the telencephalon; 2) diencephalon; 3) midbrain; 4) the hindbrain; 5) the medulla oblongata, which at the level of the foramen magnum passes into the spinal cord.

Rice. 7.Departments of the brain



1 - terminal brain; 2 - diencephalon; 3 - midbrain; 4 - bridge; 5 - cerebellum (hindbrain); 6 - spinal cord.

The vast medial surface of the cerebral hemispheres hangs over the much smaller cerebellum and brain stem. On this surface, as on other surfaces, there are grooves that separate the gyrus of the brain from each other.

The areas of the frontal, parietal and occipital lobes of each hemisphere are separated from the large brain adhesion, which is clearly visible on the midline section, - the corpus callosum, by the groove of the same name. Under the corpus callosum is a thin white plate - the vault. All formations listed above refer to the terminal brain, telencephalon.

The structures below, with the exception of the cerebellum, belong to the brainstem. The most anterior parts of the brain stem are formed by the right and left visual hillocks - this is the posterior thalamus. The thalamus is located downward from the body of the fornix and corpus callosum and behind the pillar of the fornix. In the midline section, only the medial surface of the posterior thalamus is discernible. On it interthalamic fusion stands out. The medial surface of each posterior thalamus borders on the side a slit-like, vertically located cavity of the third ventricle. An interventricular opening is located between the anterior end of the thalamus and the column of the fornix, through which the lateral ventricle of the cerebral hemisphere communicates with the cavity of the third ventricle. In the posterior direction from the interventricular opening, the hypothalamic groove stretches around the thalamus from below. The formations located downward from this groove belong to the hypothalamus. These are the optic chiasm, gray tubercle, funnel, pituitary gland and mastoid bodies, which are involved in the formation of the bottom of the third ventricle.

Above and behind the optic hillock, under the corpus callosum, is the pineal gland.

The thalamus (optic tubercle), hypothalamus, III ventricle, pineal gland belong to the diencephalon.

Caudal to the thalamus are the formations related to the midbrain, mesencephalon. Below the pineal gland is the roof of the midbrain (plate of the quadruple), consisting of the upper and lower hillocks. The ventral lamina of the midbrain roof is the cerebral peduncle, separated from the lamina by the aqueduct of the midbrain. The aqueduct of the midbrain connects the cavities of the III and IV ventricles. Even more posteriorly, there are midline incisions of the pons and cerebellum, related to the hindbrain and the incision of the medulla oblongata. The cavity of these parts of the brain is the IV ventricle. The bottom of the IV ventricle is formed by the dorsal surface of the pons and the medulla oblongata, which constitutes a rhomboid fossa on the whole brain. The thin plate of white matter that stretches from the cerebellum to the roof of the midbrain is called the superior cerebral sail.

4. Cranial nerves

On the basis of the brain, in the anterior regions formed by the lower surface of the frontal lobes of the cerebral hemispheres, olfactory bulbs can be found. They look like small thickenings located on the sides of the longitudinal slit of the large brain. To the ventral surface of each of the olfactory bulbs from the nasal cavity through the holes in the plate of the ethmoid bone, 15-20 thin olfactory nerves (I pair of cranial nerves) fit.

A cord stretches back from the olfactory bulb - the olfactory tract. Back sections olfactory tract thicken and widen, forming an olfactory triangle. The posterior side of the olfactory triangle turns into a small area with a large number of small holes remaining after removal choroid... Medial to the perforated substance, closing the posterior parts of the longitudinal slit of the large brain on the lower surface of the brain, there is a thin, gray, easily ruptured terminal, or terminal, plate. Behind this plate is the optic chiasm. It is formed by fibers that follow as part of the optic nerves (II pair of cranial nerves), penetrating into the cranial cavity from the orbits. Two optic tracts extend from the optic chiasm in the posterolateral direction.

A gray tubercle is adjacent to the posterior surface of the optic chiasm. The lower sections of the gray tubercle are elongated in the form of a tube tapering downward, which is called a funnel. At the lower end of the funnel is a rounded formation - the pituitary gland, the endocrine gland.

Two white spherical eminences - mastoid bodies - adjoin the gray tubercle behind. Behind the optic tracts, two longitudinal white ridges are visible - the legs of the brain, between which there is a depression - the inter-pectoral fossa, bounded in front by the mastoid bodies. On the medial, facing surfaces of the brain pedicles, the roots of the right and left oculomotor nerves (III pair of cranial nerves) are visible. The lateral surfaces of the legs of the brain bend around the trochlear nerves (IV pair of cranial nerves), the roots of which leave the brain not on the basis of it, as in all other 11 pairs of cranial nerves, but on the dorsal surface, behind the lower hillocks of the roof of the midbrain, on the sides of the frenulum upper cerebral sail.

The legs of the brain come out from the back of the upper sections of a wide transverse ridge, which is designated as a bridge. The lateral sections of the pons continue into the cerebellum, forming a paired middle cerebellar pedicle.

On the border between the bridge and the middle cerebellar legs, on each side, you can see the root of the trigeminal nerve (V pair of cranial nerves).

Below the bridge are the anterior sections of the medulla oblongata, which are represented by medially located pyramids, separated from each other by the anterior median fissure. Lateral to the pyramid is a rounded elevation - an olive. On the border of the bridge and the medulla oblongata, on the sides of the anterior median fissure, the roots of the abducens nerve (VI pair of cranial nerves) emerge from the brain. Still lateral, between the middle cerebellar peduncle and the olive, on each side, the roots of the facial nerve (VII pair of cranial nerves) and the vestibular nerve (VIII pair of cranial nerves) are sequentially located. The dorsal olive in an inconspicuous groove runs from the front to the back of the roots of the following cranial nerves: glossopharyngeal (IX pair), vagus (X pair), and accessory (XI pair). The roots of the accessory nerve also branch off from the spinal cord in its upper part - these are the spinal roots. In the groove separating the pyramid from the olive, there are the roots of the hypoglossal nerve (XII pair of cranial nerves).

Topic 4. External and internal structure of the medulla oblongata and pons

1. The medulla oblongata, its nuclei and pathways

The hindbrain and medulla oblongata were formed as a result of the division of the rhomboid cerebral bladder. The hindbrain, metencephalon, includes the pons located in front (ventral) and the cerebellum, which is located behind the pons. The cavity of the hindbrain, and with it the medulla oblongata, is the IV ventricle.

The medulla oblongata, medulla oblongata (myelencephalon), is located between the hindbrain and the spinal cord. Upper bound of the medulla oblongata on the ventral surface of the brain passes along the lower edge of the bridge, on the dorsal surface it corresponds to the cerebral stripes of the IV ventricle, which divide the bottom of the IV ventricle into the upper and lower parts.

The border between the medulla oblongata and the spinal cord corresponds to the level of the foramen magnum or the exit point from the brain of the upper part of the roots of the first pair of spinal nerves.

The upper parts of the medulla oblongata are somewhat thickened in comparison with the lower ones. In this regard, the medulla oblongata takes the form of a truncated cone or bulb, for the similarity with which it is also called a bulb - bulbus, bulbus.

The length of the medulla oblongata of an adult is 25 mm on average.

In the medulla oblongata, the ventral, dorsal and two lateral surfaces are distinguished, which are separated by grooves. The grooves of the medulla oblongata are a continuation of the grooves of the spinal cord and bear the same names: the anterior median fissure, the posterior median groove, the anterolateral groove, the posterolateral groove. On both sides of the anterior median fissure on the ventral surface of the medulla oblongata, there are convex, gradually tapering pyramidal ridges, pyramides.

In the lower part of the medulla oblongata, the bundles of fibers that make up the pyramids pass to the opposite side and enter the lateral cords of the spinal cord. This transition of fibers is called the intersection of the pyramids. The intersection also serves as the anatomical border between the medulla oblongata and the spinal cord. On the side of each pyramid of the medulla oblongata is an oval elevation - an olive, oliva, which is separated from the pyramid by an anterolateral groove. In this groove, the roots of the hypoglossal nerve (XII pair) emerge from the medulla oblongata.

On the dorsal surface, on the sides of the posterior median sulcus, the thin and wedge-shaped bundles of the posterior cords of the spinal cord, separated from each other by the posterior intermediate sulcus, end with thickenings. The overlying more medially thin bundle forms the tubercle of the thin nucleus. Laterally, a wedge-shaped bundle is located, which forms a tubercle of a wedge-shaped nucleus on the side of the tubercle of a thin bundle. Dorsal to the olive from the posterolateral groove of the medulla oblongata - behind the olive groove, the roots of the glossopharyngeal, vagus and accessory nerves (IX, X and XI pairs) emerge.

The dorsal part of the lateral cord slightly widens upward. Here it is joined by fibers extending from the wedge-shaped and delicate nuclei. Together, they form the inferior cerebellar peduncle. The surface of the medulla oblongata, limited from below and laterally by the lower cerebellar legs, participates in the formation of the rhomboid fossa, which is the bottom of the IV ventricle.

A cross-section through the medulla oblongata at the level of the olives shows accumulations of white and gray matter. In the inferolateral sections, there are the right and left inferior olive kernels.

They are curved in such a way that their gates are directed medially and upward. Slightly above the lower olive nuclei is the reticular formation formed by the interlacing of nerve fibers and the nerve cells lying between them and their clusters in the form of small nuclei. Between the lower olive kernels is the so-called inter-olive layer, represented by the inner arcuate fibers - the processes of cells that lie in the thin and wedge-shaped nuclei. These fibers form a medial loop. The fibers of the medial loop belong to the proprioceptive pathway of the cortical direction and form the intersection of the medial loops in the medulla oblongata. In the upper-lateral parts of the medulla oblongata, the right and left lower cerebellar pedicles are visible in section. Several ventral fibers of the anterior spinal cord and red-nuclear-spinal tract pass. In the ventral part of the medulla oblongata, on the sides of the anterior median fissure, there are pyramids. Above the intersection of the medial loops is the posterior longitudinal bundle.

In the medulla oblongata lie the nuclei of the IX, X, XI and XII pairs of cranial nerves, which take part in the innervation of the internal organs and derivatives of the branchial apparatus. Ascending pathways to other parts of the brain also pass here. The ventral regions of the medulla oblongata are represented by descending motor pyramidal fibers. Dorsolaterally, through the medulla oblongata, there are ascending pathways connecting the spinal cord with the cerebral hemispheres, the brain stem and with the cerebellum. In the medulla oblongata, as in some other parts of the brain, there is a reticular formation, as well as such vital centers as the centers of blood circulation and respiration.

Fig 8.1. The anterior surfaces of the frontal lobes of the cerebral hemispheres, diencephalon and midbrain, pons and medulla oblongata.

III-XII - the corresponding pairs of cranial nerves.

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    • The central nervous system (CNS) in the human body is represented by two brain elements: the head and the spinal. The human skeleton has a spinal canal, where the spinal cord is located. What functions does it perform?

    It performs two vital functions:

    • conductor (paths for transmitting impulse signals);
    • reflex-segmental.

    The conductive function is carried out by the transmission of impulses along the ascending cerebral pathways to the brain and back to the executing organs along the descending cerebral pathways. Long paths for the transmission of impulse signals allow them to be transmitted from the spinal cord to different functional parts of the brain, and short ones provide communication between adjacent segments of the spinal cord.

    The reflex function is reproduced by activating a simple reflex arc (knee reflex, extension and flexion of the arms and legs). Complex reflexes are reproduced with the participation of the brain. The spinal cord is also responsible for the implementation of autonomic reflexes, which control the work of the human internal environment - the digestive, urinary, cardiovascular, reproductive systems. The diagram below illustrates the functions vegetative system in organism. Autonomic and motor reflexes are controlled by proprioceptors in the thickness of the spinal cord. The structure and function of the spinal cord have a number of features in humans.

    Let's consider the structure of the spinal cord for a better understanding of what functions it performs.

    Anatomical features

    The structure of the human spinal cord is not as simple as it might seem at first. Outwardly, the back of the brain resembles a cord with a diameter of up to 1 cm, a length of 40-45 cm. It originates from the oblong part of the brain and ends with a cauda equina to the end of the spinal column. The vertebrae protect the spinal cord from damage.

    The spinal cord is a cord, it is formed by the brain tissue. Throughout its length, it has a rounded shape in cross section, the only exceptions are thickening zones, where its flattening is observed. The cervical thickening is located from the third vertebra of the neck to the first thoracic vertebra. Lumbosacral flattening is localized in the region of 10-12 vertebra of the thoracic region.

    In front and behind the spinal cord, on its surface, it has grooves that divide the organ into two halves. The brain cord has three sheaths:

    • firm - is a white shiny dense fibrous tissue, rich in elastic fibers;
    • arachnoid - made of endothelium-coated connective tissue;
    • choroid - a membrane of loose connective tissue rich in blood vessels to provide nutrition to the spinal cord.

    CSF (cerebrospinal fluid) is located between the two lower layers.

    The central sections of the spinal cord are filled with gray matter. On the preparation of an organ cut, this substance resembles a butterfly in outline. This component of the brain consists of the bodies of nerve cells (insertional and motor type). This part of the nervous system is divided into functional zones: the anterior and posterior horns. The former contain motor-type neurons, the latter have intercalary nerve cells. There are additional lateral horns along the segment of the spinal cord from the 7th cervical segment to the 2nd lumbar segment. It contains the centers responsible for the functioning of the autonomic NS (nervous system).

    The hind horns are characterized by their heterogeneous structure. As part of these areas of the spinal cord, there are special nuclei made by intercalary neurons.

    The outer part of the spinal cord is formed by a white matter made by the axons of the butterfly neurons. The spinal grooves conditionally divide the white matter into 3 pairs of cords, known as: lateral, posterior and anterior. Axons are combined into several conductive tracts:

    • associative fibers (short) - provide a connection between various spinal segments;
    • ascending fibers, or sensitive, - transmit nerve signals to the head of the central nervous system;
    • descending fibers, or motor, - transmit impulse signals from the cerebral cortex to the anterior horns, which control the executing organs.

    The posterior cords contain only ascending conductors, and the remaining two pairs are characterized by the presence of descending and ascending conduction pathways. The number of conductive paths in the cords is different. The table below shows the location of the conduction tracts in the dorsal part of the central nervous system.

    Lateral guide wire:

    • spinal cord (posterior) - transmits impulse signals of a proprioceptive nature to the cerebellum;
    • spinal cord (anterior) - is responsible for communication with the cerebellar cortex, where it transmits impulse signals;
    • spinal thalamic tract (external lateral) - is responsible for the transmission of impulse signals to the brain from receptors that respond to pain and temperature changes;
    • pyramidal tract (external lateral) - conducts motor impulse signals from the cortex of large hemispheres to the spinal cord;
    • red-spinal tract - controls the maintenance of skeletal muscle tone and regulates the performance of subconscious (automatic) motor functions.

    Anterior cord of the conductors:

    • pyramidal tract (anterior) - transmits a motor signal from the cortex of the upper parts of the central nervous system to the lower;
    • dorsal thalamic tract (anterior) - transmits impulse signals from tactile receptors;
    • vestibular-spinal - carries out the coordination of conscious movements and balance, and is also characterized by the presence of a connection with the medulla oblongata.

    The posterior cord of the conductors:

    • Gaulle's thin fiber bundle - responsible for the transmission of impulse signals from proprioceptors, interoreceptors and skin receptors of the lower parts of the trunk and legs to the brain;
    • wedge-shaped bundle of Burdakh fibers - responsible for the transmission of the same receptors to the brain from the arms and upper torso.

    The human spinal cord in its structure belongs to the segmental organs. How many segments does it have in the human body? In total, the cord cord contains 31 segments, corresponding to the sections of the spine:

    • in the cervical - eight segments;
    • in the chest - twelve;
    • in the lumbar - five;
    • in the sacrum - five;
    • in the tailbone - one.

    The cord cord segments each have four roots that form the spinal nerves. The dorsal roots are formed from the axons of sensory neurons, they enter the dorsal horns. The dorsal roots have sensitive ganglia (one on each). Then, in this place, a synapse is formed between the sensory and motor cells of the NS. The axons of the latter form the anterior roots. This diagram shows the structure of the spinal cord and its roots.

    In the center of the spinal cord along its entire length, the canal is localized, it is filled with cerebrospinal fluid. To the head, arms, lungs and heart muscle, conductive fibers extend from the cervical and upper chest segments. Segments of the lumbar and thoracic region of the brain give off nerve endings to the muscles of the trunk and abdominal cavity with its contents. The lower lumbar and sacral segments of a person give off nerve fibers to the legs and muscles of the lower press.

    SPINAL CORD.

    Spinal cord, medulla spipalis(Greek muelos), lies in the vertebral canal and in adults it is represented by a long, slightly flattened front cylindrical cord from the level of for.magnum and L II (in women).

    External structure.

    In the spinal cord, there are:

    Cervical thickening, intumescentia cervicalis, is the area of ​​the spinal cord that provides innervation upper limbs, is located from C5 to Th1;

    Lumbosacral thickening, intumescentia lumbosacralis, - the area of ​​the spinal cord that provides innervation to the lower extremities, is located from Th12 to S3;

    Brain cone , conus medullaris, - the lower, narrowed area of ​​the spinal cord;

    Terminal thread, filum teminale;

    Anterior median fissure, fissura mediana anterior;

    Back median fissure, sulcus medianus posterior;

    The anterior lateral groove, sulcus ventrolateralis, is the exit site of the anterior roots of the spinal nerves;

    The posterior lateral groove, sulcus dorsolateralis, is the exit site of the posterior roots of the spinal nerves; the posterior root has a thickening - a spinal cord node, ganglion spinale, containing pseudo-unipolar nerve cells.

    Throughout the SM, 124 roots depart: 62 posterior and 62 anterior (of which 31 pairs of spinal nerves are formed):

    The posterior root of the spinal nerve is a collection of central processes of pseudo-unipolar cells that travel from the spinal ganglion to the spinal cord;

    The anterior root of the spinal nerve is a set of axons of the cells of the motor nuclei of the anterior horns of the SM, heading from the exit site of their anterior lateral groove of the SM to the entrance to the spinal nerve.

    Spinal cord segment- the CM site corresponding to two pairs of spinal nerve roots located at the same level in the horizontal plane.

    In the spinal cord, 31 segments are distinguished, which are topographically divided into 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal.

    Ponytail, cauda equina, is a set of spinal nerve roots extending from ten lower segments and a filament (40 roots: 20 anterior and 20 posterior).

    Internal structure spinal cord.

    1. Gray substance, substantia grisea , on the cross section, the CM is located inside and has the shape of a butterfly; it is represented mainly by the bodies of nerve cells. More than 90% of the gray matter is scattered cells, cellulae dissiminatae. In the middle of it there is a narrow central canal, canalis centralis, of the spinal cord, passing the entire length of the last and containing spinal fluid. The central channel is the remainder of the primary nerve tube. Therefore, above it, it communicates with the IV ventricle of the cerebral cord, and in the area of ​​the conus medullaris, it ends with an extension - the end ventriculus terminalis.

    In the gray matter of CM, there are:

    1) anterior horn, cornu anterius , which contains its own nuclei, nuclei proprii cornu anterius;

    2) posterior horn, cornu posterius in which there are

    Own nucleus of the posterior horn, nucleus proprius cornu posterioris;

    Thoracic nucleus, nucleus thoracicus; in the thoracic segments, it is called the Clarke nucleus, in the cervical segments, the Stilling nucleus;

    Gelatinous substance, substantia gelatinosa, located in the region of the apex of the posterior horn;

    The spongy zone, zona spongiosa, is located dorsal to the gelatinous substance;

    Border zone, zona terminalis, - the outermost layer of the posterior horns.

    3) lateral horn, cornu laterale , located in segments C8 - L3; it contains the lateral intermediate nucleus, nucleus intermediolateralis;

    4) intermediate substance, substantia intermedia , - the central part of the gray matter; it contains:

    Medial intermediate nucleus, nucleus intermediomedialis;

    The sacral parasympathetic nuclei, nuclei parasympathici sacrales, are located in the sacral segments (S2 - S4) between the anterior and posterior horns;

    The spinal nucleus of the accessory nerve, nucieus spinalis n.accessorii, (in segments C1 - C6);

    The nucleus of the spinal tract of the trigeminal nerve, nucieus spinalis n.trigemini, (at the base of the posterior horn of the segments C1 - C4).

    2. White substance, substantia alba.

    The white matter consists mainly of processes (myelin fibers) of nerve cells that form:

    1) the anterior cord, funiculus anterior, limited to the fissura mediana anterior and s.dorsolateralis;

    2) the lateral cord, funiculus lateralis, limited to s.ventrolateralis and s.dorsolateralis;

    3) the posterior cord, funiculus posterior, limited to the s.medianus posterior and s.dorsolateralis.

    Each cord consists of bundles of nerve fibers (axons), which are united by their common origin and functional purpose into nerve tracts.

    SPINAL CORD COMPOSITION.

    Rear cords contain afferent (ascending, sensitive) pathways:

    1) thin bunch, fasciculus gracilis (Gaul's bunch); a thin bundle is formed by the axons of the spinal ganglion on its side. It conducts impulses of proprioceptive and tactile sensitivity from the lower limbs and trunk (from 19 lower segments).

    2) wedge-shaped bundle , fasciculus cuneatus (bunch of Burdakh); conducts impulses of proprioceptive and tactile sensitivity from the upper limbs and upper body (from the 12 upper segments).

    3) posterior intrinsic bundle , fasciculus proprius posterior; formed by the axons of the intercalated neurons of the segmental apparatus.

    4) dorsal root fibers that form radicular area , zona radicularis.

    Lateral cords contain the following pathways:

    A. Ascending.

    To the back brain:

    1) posterior spinal-cerebellar path , tractus spinocerebellaris posterior, (Flexig's bundle), spread in the back part of the lateral canal on its periphery; formed by the axons of the nucleus thoracicus of its side, conducts impulses of unconscious proprioceptive sensitivity to the cerebellum.

    2), neprederal spinal-cerebellar path , tractus spinocerebellaris anterior, lies in front of the previous; conducts unconscious proprioceptive impulses.

    To the middle brain:

    3) dorsal-roof pathway, tractus spinotestalis, adjoins the medial side and the front part of tractus sinocerebellaris anterior.

    To the intermediate brain:

    4) lateral dorsal thalamic tract , tractus spinothalamicus lateralis adjoins from the medial side to tractus sinocerebellaris anterior, just after tractus sinotectalis. He conducts temperature irritations in the upper part of the treaty, and painful irritations in the ventral part.

    B. Descendants.

    From the bark of a large brain:

    1) lateral cortical-spinal cord (pyramidal) path , tractus orticospinalis (pyramidalis) lateralis. This tract is a conscious effective motor path.

    From the middle brain:

    2) red-spinal path , tractus rubrospinalis. It is an unconscious effective motor path, maintains skeletal muscle tone (posture) and performs complex automated movements (running, walking).

    From the back brain:

    3) olive-spinal path , tractus oIivоspinalis, lies ventrally to tractus spinocerebellaris anterior, near the anterior cath.

    4) predoor-spinal path , tractus vestibulospinalis, is formed by the axons of the vestibular nuclei of the bridge and provides a redistribution of muscle tone in response to a change in body position in space.

    Front cords contains descending paths.

    From the bark of the brain:

    1) anterior cortex-spinal cord (pyramidal) path , tractus corticospinalis (pyramidalis) anterior, constitutes a common pyramidal system with a lateral pyramidal bundle.

    From the average brain:

    2) tegmental-spinal path, tractus testospinalis, lies medial to the pyramidal bundle, limiting the fissura mediana anterior. Thanks to it, reflective protective movements occur during spectator and auditory irritations - an auditory-auditory reflexive act.

    From various nuclei of an extended brain, which have a relation to the equality and coordination of movements, a name is:

    3) from the nucleus of the vestibular nerve - tractus vestibulospinalis - lies at the border of the anterior and lateral canals;

    4) from formatio reticularis - tractus reticulospinalis anterior, lies in the middle part of the anterior canal;

    5) the intrinsic bundles, fasciculi proprii, adhere to the substance and refer to the intrinsic apparatus of the spinal cord.

    6) tractus spinothalamicus anterior s. ventralis, is the way of conducting impulses of occlusion, touch (tactile sensitivity).

    )

    common name paired areas of the white matter of the spinal cord, limited by its cracks and grooves.

    Spinal cord lateral canal(f. lateralis) - with brain Lateral cord .

    Rear spinal cord canal(f. posterior) - with brain Posterior cord .

    Spinal cord anterior(f. anterior) - with brain Anterior cord .


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

    See what "Cord of the spinal cord" is in other dictionaries:

      - (funiculus medullae spinalis, PNA, BNA; fasciculus medullae spinalis, JNA) the general name of the paired areas of the white matter of the spinal cord, limited by its cracks and grooves ... Comprehensive Medical Dictionary

      - (f. lateralis) see Lateral cord ... Comprehensive Medical Dictionary

      - (f. posterior) see. Posterior cord ... Comprehensive Medical Dictionary

      - (f. anterior) see Anterior cord ... Comprehensive Medical Dictionary

      Medical terms

      CORD- 1. A set of fibers that form any of the three columns of the white matter of the spinal cord. 2. A bundle of nerve fibers, covered with a sheath; bunch. 3. (Obsolete) spermatic or umbilical cord. 4. (Funis) (in anatomy) any chord-like structure, in ... Explanatory Dictionary of Medicine

      - (funiculus lateralis, PNA, JNA; funiculus lateralis (medullae spinalis), BNA: synonym: lateral cord of the spinal cord, lateral cord) a set of longitudinally extending bundles of nerve fibers of the spinal cord located between the exit line ... ... Comprehensive Medical Dictionary

      - (funiculus posterior, PNA: funiculus posterior (medullae) spinalis, BNA; synonym: dorsal cord, cord of the spinal cord of the back) a paired bundle of nerve fibers in the white matter of the spinal cord, located between the posterior median and posterior ... Comprehensive Medical Dictionary

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

      The system of efferent neurons, whose bodies are located in the cerebral cortex, end in the motor nuclei of the cranial nerves and the gray matter of the spinal cord. As part of the pyramidal pathway (tractus pyramidalis), cortical nuclear fibers are emitted ... ... Medical encyclopedia

      A set of longitudinally extending bundles of nerve fibers of the spinal cord located between the exit line ... ... Medical encyclopedia


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