The spinal cord is an elongated cord that has a cylindrical shape. Inside the spinal cord there is a narrow central canal. The anatomy of the organ reveals the incredible capabilities of the spinal cord, and also reveals its critical role and importance for maintaining the vital functions of the entire organism.

Anatomical features

The organ is located in the cavity of the spinal canal. This cavity is formed by the bodies and processes of the vertebrae.

The structure of the spinal cord begins with the brain, in particular, with the lower border of the small foramen magnum. It ends at the level of the first lumbar vertebrae. At this level, narrowing occurs into the medullary sinus.

The filum terminale branches down from the medullary sinus. The thread has upper and lower sections. The upper sections of this thread have some elements of nervous tissue.

At the level of the lumbar region of the spinal column, the conus medullaris is a formation of connective tissue consisting of three layers.

The filum terminale ends at the second coccygeal vertebra, at which point it fuses with the periosteum. The spinal cord roots wrap around the filum terminale. They form a bun, which experts don’t call “ponytail” for nothing.

The length of the spinal cord is approximately forty-five centimeters, and it weighs no more than forty grams

Functional abilities

The functions of the human spinal cord play a vital role, simply necessary to maintain life. The following main functions are distinguished:

• reflex,
• conductor

The reflex function of the spinal cord gives a person the simplest motor reflexes. For example, with burns, patients begin to pull back their hands. When a hammer hits the tendon of the knee joint, a reflex extension of the knee occurs. All this became possible thanks to the reflex function. A reflex arc is the path along which nerve impulses travel. Thanks to the arc, the organ is connected to the skeletal muscles.

If we talk about the conduction function, then it lies in the fact that the ascending pathways of movement contribute to the transmission of nerve impulses from the brain to the spinal cord. And thanks to descending pathways, nerve impulses are transmitted from the brain to the internal organs of the body.

Now let's talk about the functions of the red nuclear spinal tract. It ensures the functioning of involuntary motor impulses. This pathway begins with the red nucleus and gradually descends to the motor neurons.

And the lateral corticospinal tract consists of neurites of cells of the cerebral cortex.

The blood supply to the spinal cord and brain is closely interconnected. The anterior and paired posterior spinal arteries, as well as the radicular-spinal arteries, are directly involved in ensuring that blood in sufficient quantity and on time enters the central region of the nervous system. Here the formation of choroid plexuses occurs, which correspond to the lining of the brain.

Thickenings and grooves

In the part of the nervous system under consideration, two thickenings are distinguished:

• cervical thickening;
• lumbosacral thickening.

The dividing boundaries are considered to be the anterior median fissure and the posterior sulcus. These boundaries are located between the halves of the spinal cord, which are symmetrically located.

The median fissure is surrounded on both sides by the anterior lateral groove. The motor root originates from the anterior lateral sulcus.

The organ has lateral and anterior cords. The anterior lateral groove separates these cords from each other. The role of the posterior lateral sulcus is also important. At the back it plays the role of a kind of border.

Roots

The anterior roots of the spinal cord are nerve endings that are contained in the gray matter. The dorsal roots are sensitive cells, or rather, their processes. The spinal ganglion is located at the junctions of the anterior and posterior roots. This node is created by sensitive cells.

The location of a particular segment does not correspond to the serial number of the vertebra. This is because the length of the spinal cord is slightly shorter than the length of the spinal column

The roots of the human spinal cord extend from the spinal column on either side. Thirty-one roots emerge from the left and right sides.

A segment is a specific part of an organ located between each pair of such roots.

If you remember the mathematics, it turns out that each person has thirty-one such segments:

• five segments are in the lumbar region;
• five sacral segments;
• eight cervical;
• twelve breasts;
• one coccygeal.

Gray and white matter

This part of the nervous system includes the gray and white matter of the spinal cord. The latter is formed only by nerve fibers. And gray matter, in addition to nerve fibers, is also formed by nerve cells of the brain.

The white matter of the spinal cord is surrounded by gray matter. It turns out that the gray matter is in the middle.

If you look at this substance in a cross section, it strongly resembles a butterfly

In the center of the gray matter is the central canal, which is filled with liquor fluid.

Cerebrospinal fluid circulates due to the interaction of the following components:

• central channel of the organ;
• ventricles of the brain;
• the space that is located between the meninges.

Pathologies of the central nervous system, which are diagnosed by examining the cerebrospinal fluid, can be of the following nature:

The transverse plate connects the gray pillars, from which the gray matter itself is formed.

The horns of the human spinal cord are projections extending away from the gray matter. They are divided into the following groups:

• paired wide horns. They are located on the front;
• paired narrow horns. They branch off at the back.

The study of cerebrospinal fluid is of informative value in the diagnostic study of pathologies of the central nervous system

The anterior horns are distinguished by the presence of motor neurons.

Neurites are long processes of motor neurons that form the anterior roots of the central part of the nervous system.

The nuclei of the spinal cord are created by neurons that are found in the anterior horn of the spinal cord. There are five cores:

• one central core;
• lateral nuclei - two pieces;
• medial nuclei - two pieces.

The interneurons form a nucleus, which is located in the middle of the dorsal horn.

Axons are the processes of neurons. They head towards the front horn. Axons enter the opposite region of the brain, passing through the anterior commissure

Interneurons contribute to the formation of the nucleus, which is located at the base of the dorsal horn nucleus. The ends of the nerve cell processes are located on the nuclei of the dorsal horns. These nerve cells are located in the intervertebral spinal ganglia.

The anterior and posterior horns form the intermediate part of the spinal cord. It is this area of ​​the central part of the nervous system that is the site of the branch of the lateral horns. It starts from the cervical region and ends at the level of the lumbar region.

The anterior and posterior horns are also distinguished by the presence of an intermediate substance, which consists of nerve endings responsible for part of the autonomic nervous system.

White matter is formed by three pairs of cords:

• front,
• rear,
• lateral.

White matter is formed by nerve fibers that carry nerve impulses

The anterior funiculus is bounded by the anterior lateral groove as well as the lateral groove. It is located at the exit site of the anterior roots. The lateral funiculus is limited by the posterior and anterior lateral groove. The posterior funiculus is the space between the median and lateral grooves.

Nerve impulses that follow along nerve fibers can be sent both to the brain and to the lower parts of the central nervous system.

Types of pathways

The conductive tracts of the spinal cord are located outside the spinal cords. The impulses that come from neurons are directed along the ascending pathways. In addition, impulses from the brain to the motor center of the central nervous system follow these paths.

The supply of impulses from the nerve endings of the joints and muscles to the medulla oblongata occurs due to the work of the thin and wedge-shaped fasciculus. The bundles carry out the conductive function of the central part of the nervous system.

The impulses that pass from the arms and torso and are directed to the lower part of the body are regulated by the wedge bundle. And the impulses that go from the skeletal muscles to the cerebellum are regulated by the anterior and posterior spinocerebellar pathways. In the posterior horn, or more precisely in its medial part, there are cells of the thoracic nucleus, from which the posterior part of this path originates. This path is located on the posterior side of the lateral funiculus.

The anterior part of the spinocerebellar tract is distinguished. It is formed by branches of interneurons, which are located in the nucleus of the intermedial region.

The lateral spinothalamic tract is also distinguished. It is formed by interneurons on the opposite side of the horn.

The spinothalamic tract plays an important role in the body, it conducts pain sensations, as well as temperature sensitivity

Shells

This section of the nervous system is the connecting link between the main section and the periphery. It regulates nervous activity at the reflex level.

There are three connective tissue membranes of the spinal cord:

• hard – is the outer shell;
• arachnoid - medium;
• soft - internal.

The membranes of the spinal cord have their continuation into the membranes of the brain.

Structure and functions of the hard shell

The hard shell is a wide, cylindrical sac stretched from top to bottom. In appearance, it is a dense, shiny, whitish fibrous tissue that has a huge number of elastic strands.

From the outside, the surface of the hard shell is directed towards the walls of the spinal canal and has a rough base.

The arachnoid membrane is the middle shell, it is a thin transparent sheet that does not have blood vessels

When the shell approaches the head, fusion occurs with the occipital bone. It transforms nerves and nodes into peculiar containers that expand towards the openings located between the vertebrae.

The blood supply to the dura mater is carried out by spinal arteries arising from the abdominal and thoracic aorta.

The formation of choroid plexuses occurs in the corresponding meninges. Arteries and veins accompany each spinal root.

Doctors of various specializations must identify and treat pathological processes. It is often possible to provide assistance and prescribe the correct treatment if you are examined by all the necessary specialists.

If you neglect the complaints that have arisen, the pathological process will develop even more and progress.

Arachnoid

Near the nerve roots, the arachnoid membrane connects to the dura mater. Together they form the subdural space.

Soft shell

The soft membrane covers the central part of the nervous system. This is a delicate, loose connective tissue covered by the endothelium. The soft shell consists of two leaves that contain numerous blood vessels.

With the help of vessels, it not only envelops the spinal cord, but also enters its very substance.

The vascular base is the so-called vagina, which forms a soft membrane near the vessel.

The vascular network of the vertebral arteries joins together during descent and forms vascular branches

Intershell space

The epidural space is a space that is formed by the periosteum and dura mater.

Space contains the following important elements of the central nervous system:

• fatty tissue;
• connective tissue;
• extensive venous plexuses.

The subarachnoid space is a space located at the level of the arachnoid and soft shell. The nerve roots, as well as the brain of the subarachnoid space, are surrounded by cerebrospinal fluid.

Common pathologies of the membranes of the central nervous system are:

So, the spinal cord is the most important element of the whole organism, performing functions of vital importance. The study of anatomical features once again convinces us that in our body each organ plays its own role. There is nothing superfluous in it.

medulla spinalis) has, in comparison with the brain, a relatively simple structural principle and a pronounced segmental organization. It provides connections between the brain and the periphery and carries out segmental reflex activity.

The spinal cord lies in the spinal canal from the upper edge of the first cervical vertebra to the first or upper edge of the second lumbar vertebra, repeating to a certain extent the direction of curvature of the corresponding parts of the spinal column. In a 3-month-old fetus it ends at the level of the V lumbar vertebra, in a newborn - at the level of the III lumbar vertebra.

The spinal cord, without a sharp boundary, passes into the medulla oblongata at the site of exit of the first cervical spinal nerve. Skeletotopically, this boundary passes at the level between the lower edge of the foramen magnum and the upper edge of the first cervical vertebra.

Below the spinal cord passes into the conus medullaris (lat. conus medullaris), continuing into the terminal (spinal) filament (lat. filum terminale (spinale)), which has a diameter of up to 1 mm and is a reduced part of the lower part of the spinal cord. The filum terminale, with the exception of its upper sections where there are elements of nervous tissue, is a connective tissue formation. Together with the dura mater, it penetrates the sacral canal and is attached at its end. That part of the filum terminale, which is located in the cavity of the dura mater and is not fused with it, is called the internal filum terminale (lat. filum terminale internum), its remaining part, fused with the dura mater, is the external filum terminale (lat. filum terminale externum). The filum terminale is accompanied by the anterior spinal arteries and veins, as well as one or two roots of the coccygeal nerves.

The spinal cord does not occupy the entire cavity of the spinal canal: between the walls of the canal and the brain there remains a space filled with adipose tissue, blood vessels, meninges and cerebrospinal fluid.

The length of the spinal cord in an adult ranges from 40 to 45 cm, width - from 1.0 to 1.5 cm, and weight is on average 35 g.

There are 4 surfaces of the spinal cord:

The spinal cord does not have the same diameter throughout. Its thickness increases slightly from bottom to top. The largest size in diameter is observed in two fusiform thickenings: in the upper part - this is the cervical thickening (lat. intumescentia cervicalis), corresponding to the exit of the spinal nerves going to the upper limbs, and in the lower part - this is the lumbosacral thickening (lat. intumescentia lumbosacralis), - the place where nerves exit to the lower extremities. In the area of ​​the cervical thickening, the transverse size of the spinal cord reaches 1.3-1.5 cm, in the middle of the thoracic part - 1 cm, in the area of ​​the lumbosacral thickening - 1.2 cm; the anteroposterior size in the area of ​​thickenings reaches 0.9 cm, in the thoracic part - 0.8 cm.

The cervical thickening begins at the level of the III-IV cervical vertebra, reaches the II thoracic vertebra, reaching its greatest width at the level of the V-VI cervical vertebra. The lumbosacral thickening extends from the level of the IX-X thoracic vertebra to the I lumbar vertebra, its greatest width corresponds to the level of the XII thoracic vertebra (at the height of the 3rd lumbar spinal nerve).

The shape of cross sections of the spinal cord at different levels is different: in the upper part the section has the shape of an oval, in the middle part it is round, and in the lower part it is close to square.

On the anterior surface of the spinal cord, along its entire length, lies the anterior median fissure (lat. fissura mediana ventralis), into which the fold of the pia mater is invaginated - the intermediate cervical septum (lat. septum cervicale intermedium). This gap is less deep at the upper and lower ends of the spinal cord and is most pronounced in its middle parts.

On the posterior surface of the brain there is a very narrow posterior median sulcus (lat. sulcus medianus dorsalis), into which a plate of glial tissue penetrates - the posterior median septum (lat. septum medianum dorsale). The fissure and groove divide the spinal cord into two halves - right and left. Both halves are connected by a narrow bridge of brain tissue, in the middle of which is the central canal (lat. canalis centralis) spinal cord.

On the lateral surface of each half of the spinal cord there are two shallow grooves. Anterolateral groove (lat. sulcus ventrolateralis), located outward from the anterior median fissure, more distant from it in the upper and middle parts of the spinal cord than in its lower part. Posterolateral groove (lat. sulcus dorsoolateralis), lies lateral to the posterior median sulcus. Both grooves run along the entire length of the spinal cord.

In the cervical and partly in the upper thoracic regions, between the posterior median and posterolateral grooves, there is a vaguely defined posterior intermediate groove (lat. sulcus intermedius dorsalis) .

In the fetus and newborn, a rather deep anterior intermediate sulcus is sometimes found, which, following the anterior surface of the upper cervical part of the spinal cord, is located between the anterior median fissure and the anterolateral sulcus.

A characteristic feature of the spinal cord is its segmentation and the correct periodicity of the exit of the spinal nerves.

The spinal cord is divided into 5 parts: cervical (lat. pars cervicalis), chest (lat. pars thoracica), lumbar (lat. pars lumbalis), sacral (lat. pars sacralis) and coccygeal part (lat. pars coccygea). At the same time, the assignment of a segment of the spinal cord to one or another part depends not on its actual location, but on the section in which the nerves emerging from it leave the spinal canal. The cervical part consists of 8 segments, the thoracic part - 12, the lumbar part - 5, the sacral part - 5, the coccygeal part - from 1 to 3. A total of 31 - 33 segments.

Spinal cord roots

The anterior radicular filaments (lat. fila radicularia), which are the axons of nerve cells. The anterior radicular filaments form the anterior (motor) root (lat. radix ventralis). The anterior roots contain centrifugal efferent fibers that conduct motor impulses to the periphery of the body: to striated and smooth muscles, glands, etc.

The posterolateral groove includes the posterior root filaments, consisting of processes of cells located in the spinal ganglion. The posterior radicular filaments form the dorsal root (lat. radix dorsalis). The dorsal roots contain afferent (centripetal) nerve fibers that conduct sensory impulses from the periphery, i.e. from all tissues and organs of the body, to the central nervous system. On each dorsal root there is a spinal ganglion (lat. ganglion spinale) .

The direction of the roots is not the same: in the cervical region they extend almost horizontally, in the thoracic region they go obliquely downwards, in the lumbosacral region they go straight down.

The anterior and posterior roots of the same level and one side immediately outside the spinal ganglion are connected, forming the spinal nerve (lat. n. spinalis), which is therefore mixed. Each pair of spinal nerves (right and left) corresponds to a specific area - segment - of the spinal cord.

Consequently, the spinal cord has as many segments as there are pairs of spinal nerves.

White and gray matter

Transverse sections of the spinal cord show the location of the white and gray matter. Gray matter occupies the central part and is shaped like a butterfly with outstretched wings or a letter N. White matter is located around the gray matter, on the periphery of the spinal cord.

The ratio of gray to white matter varies in different parts of the spinal cord. In the cervical region, especially at the level of the cervical thickening, there is much more gray matter than in the middle sections of the thoracic region, where the amount of white matter is much (about 10-12 times) greater than the mass of gray matter. In the lumbar region, especially at the level of the lumbar enlargement, there is more gray matter than white matter. Towards the sacral part, the amount of gray matter decreases, but the amount of white matter decreases to an even greater extent. In the area of ​​the conus medullaris, almost the entire surface of the cross section is made of gray matter, and only along the periphery is a narrow layer of white matter.

White matter

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 running transversely in front of the central canal (lat. commissura alba) .

The sulci of the spinal cord, with the exception of the posterior intermediate sulcus, divide the white matter of each half into three cords of the spinal cord (lat. funiculi medullae spinalis). There are:

In the upper half of the thoracic part and in the cervical part of the spinal cord, the posterior intermediate groove divides the posterior cord into two bundles: a thinner medial fascicle lying inside, the so-called thin fascicle, and a more powerful lateral wedge-shaped fascicle. Below, the wedge-shaped bundle is absent. The cords of the spinal cord continue into the initial part of the brain - the medulla oblongata.

The white matter of the spinal cord contains projection, afferent and efferent pathways, as well as association fibers. The latter make connections between the segments of the spinal cord and form the anterior, lateral and posterior bundles of their own (lat. fasciculi proprii ventrales, laterales et dorsales ), which are adjacent to the gray matter of the spinal cord, surrounding it on all sides. These bundles include:

Gray matter

Gray matter of the spinal cord (lat. substantia grisea) consists mainly of nerve cell bodies with their processes that do not have a myelin sheath. It distinguishes between two lateral parts located in both halves of the spinal cord, and a transverse part connecting them in the form of a narrow bridge - the central intermediate substance (lat. substantia intermedia centralis ). It continues into the lateral parts, occupying their middle, like a lateral intermediate substance (lat. substantia intermedia lateralis ) .

In the middle sections of the central intermediate substance there is a very narrow cavity - the central canal (lat. canalis centralis). It stretches throughout the entire spinal cord, passing at the top into the cavity of the fourth ventricle. Below, in the area of ​​the conus medullaris, the central canal is expanded and its diameter reaches an average of 1 mm; This section of the central canal is called the terminal ventricle (lat. ventriculus terminalis) .

Histology

The spinal cord consists of two symmetrical halves, delimited from each other in front by a deep median fissure, and behind by a connective tissue septum. In fresh preparations of the spinal cord, the naked eye can see that its substance is heterogeneous. The inner part of the organ is darker - this is its gray matter (lat. substantia grisea). At the periphery of the spinal cord there is a lighter white matter (lat. substantia alba). Gray matter in a cross-section of the brain is represented in the shape of the letter “H” or a butterfly. The projections of gray matter are commonly called horns. There are anterior, or ventral, posterior, or dorsal, and lateral, or lateral, horns.

Along the spinal cord, the relationship between gray and white matter changes. Gray matter is represented by the smallest number of cells in the thoracic region. The largest is in the lumbar region.

Gray matter

The gray matter of the spinal cord consists of neuronal cell bodies, unmyelinated and thin myelinated fibers, and neuroglia. The main component of gray matter, distinguishing it from white matter, are multipolar neurons.

Cells similar in size, fine structure and functional significance lie in the gray matter in groups called nuclei. Among the neurons of the spinal cord, the following types of cells can be distinguished:

• radicular cells (lat. neurocytus radiculatus), the axons of which leave the spinal cord as part of its anterior roots
• internal cells (lat. neurocytus internus), the processes of which end in synapses within the gray matter of the spinal cord
• tuft cells (lat. neurocytus funicularis), the axons of which pass through the white matter in separate bundles of fibers, carrying nerve impulses from certain nuclei of the spinal cord to its other segments or to the corresponding parts of the brain, forming pathways.

Individual areas of the gray matter of the spinal cord differ significantly from each other in the composition of neurons, nerve fibers and neuroglia.

In the posterior horns there are spongy layer, gelatinous substance, And thoracic core. Between the posterior and lateral horns, the gray matter protrudes into the white matter in strands, as a result of which a network-like loosening is formed, called the reticular formation.

Spongy layer The dorsal horn is characterized by a broadly looped glial skeleton, which contains a large number of small interneurons.

IN gelatinous substance glial elements predominate. The nerve cells here are small and their number is insignificant.

The posterior horns are rich in diffusely located intercalary cells. These are small multipolar association and commissural cells, the axons of which end within the gray matter of the spinal cord of the same side (association cells) or the opposite side (commissural cells).

Neurons of the spongy zone, gelatinous substance and intercalary cells communicate between the sensory cells of the spinal ganglia and the motor cells of the anterior horns, closing local reflex arcs. In the middle of the posterior horn is located own nucleus of the dorsal horn. It consists of interneurons, the axons of which pass through the anterior white commissure to the opposite side of the spinal cord into the lateral funiculus of the white matter, where they form part of the ventral spinocerebellar and spinothalamic tracts and are sent to the cerebellum and thalamus.

Thoracic core(Clark's nucleus) consists of large interneurons with highly branched dendrites. Their axons exit into the lateral cord of the white matter on the same side and, as part of the posterior spinocerebellar tract (Flexig's tract), ascend to the cerebellum.

In the intermediate zone there are medial intermediate nucleus, the axons of the cells of which join the anterior spinocerebellar tract (Gowers tract) of the same side, and lateral intermediate nucleus, located in the lateral horns and representing a group of associative cells of the sympathetic reflex arc. The axons of these cells leave the brain along with somatic motor fibers as part of the anterior roots and are separated from them in the form of white connecting branches of the sympathetic trunk.

The anterior horns contain the largest neurons of the spinal cord, which have a body diameter of 100-150 μm and form nuclei of significant volume. This is the same as the neurons of the lateral horn nuclei, the root cells, since their axons make up the bulk of the fibers of the anterior roots. As part of the mixed spinal nerves, they enter the periphery and form motor endings in the skeletal muscles. Thus, these nuclei represent motor somatic centers. In the anterior horns, the medial and lateral groups of motor cells are most pronounced. The first innervates the muscles of the trunk and is well developed throughout the spinal cord. The second is located in the area of ​​the cervical and lumbar thickenings and innervates the muscles of the limbs.

The gray matter of the spinal cord contains many scattered tufted neurons. The axons of these cells emerge into the white matter and immediately divide into longer ascending and shorter descending branches. Together, these fibers form their own, or main, bundles of white matter, directly adjacent to the gray matter. Along their course, they give off many collaterals, which, like the branches themselves, end with synapses on the motor cells of the anterior horns of 4-5 adjacent segments of the spinal cord.

Layers of gray matter according to Rexed

What does the tone of the reticular formation depend on?

1) from the tonic effects of the striopallidal system;

2) from the tonic influences of the cerebellum;

3) from the tonic influences of the thalamus;

4) on the magnitude of the influx of afferent impulses.

1392.What function does the red nucleus perform?

1) primary visual centers;

2) regulation of muscle tone;

3) primary olfactory centers;

4) coordination of the acts of swallowing and chewing.

1393. At what level should the brain be cut for. getting decerebrate rigidity?

1) below the red nucleus;

2) at the level of the lower border of the rhomboid fossa;

3) between the 1st and 2nd cervical vertebrae of the spinal cord;

4) at the level of the lower border of the medulla oblongata.

1394.What characterizes the state of decerebrate rigidity in a cat?

1) a sharp increase in extension tone bodies of limbs, head and tail;

2) inability to maintain a standing position;

3) sharp bending of the head and tail;

4) a sharp decrease in skeletal muscle tone.

1395.What is the mechanism of decerebrate rigidity?

1) absence of corrective influences of the sensorimotor cortex of the cerebral hemispheres;

2) loss of coordination of muscle tone from the hippocampus;

3) predominance of the tone of the Deiters nucleus, unbalanced by the tone of the red nucleus;

4) cessation of the flow of afferent impulses from the periphery.

1396. How does the tone of the extensors of the forelimbs change when the head is thrown back?

1) decreases;

2) increases;

3) does not change;

4) decreases on the side of the leading hemisphere of the brain and does not change on the opposite.

1397.How does the tone of the extensors of the forelimbs change when the head is bent towards the chest?

1) increases on both sides;

2) increases on the side of the leading hemisphere of the brain;

3) decreases;

4) does not change.

1398.What is the elevator reflex?

1) Straightening the limbs when quickly lowering down and bending when quickly rum rising up;

2) fear reaction when using the elevator;

3) acceleration of the heart during a parachute jump;

4) reflex quickening and deepening of breathing when jumping with a parachute.

1399.What is the compass reflex?

1) subconscious movement in the fog towards the leading hemisphere;

2) subconscious movement in an unfamiliar forest to the right;

3) when rotating body turning the head in the direction opposite to the rotation.

4) if out of the blue a person is blindfolded and his ears are plugged, he will reflexively move only to the north.

1400.Where is the cerebellum located?

1) in the frontal lobes of the brain;

2) in the temporal lobes of the brain;

3) at the base of the brain at the sella turcica;

4) in the posterior cranial fossa above the pons medulla oblongata.

1401.What parts does the cerebellum consist of?

1) from the red nucleus, substantia nigra, reticular formation;

2) from the quadrigeminal, geniculate bodies, thalamus;

3) from a worm, two half riya and three pairs of legs;

4) from the epiphysis, globus pallidus, striatum.

1402.Which of the listed nuclei are part of the cerebellum?

1) red nucleus, globus pallidus, amygdala;

2) substantia nigra, quadrigeminal, geniculate bodies;

3) striatum, nucleus pallidus, fence;

4) paired nuclei: jagged, cork-shaped. roofing, spherical.

1403. Is it possible to live and exist normally without the cerebellum?

1) you can live, but you cannot exist independently;

2) it is a vital organ, without which life is impossible;

3) possible, because it is a vitally unimportant organ. whose functions are compensated after its removal;

4) you can live, but you cannot move independently.

1404.What influence does the cerebellum have on the locomotor apparatus?

1) none;

2) regulates the distribution of muscle tone, their performance, smoothness and coordination of movements, including voluntary ones;

3) inhibits the activity of the striopallidal system;

4) reduces the speed of reflex reactions.

1405.When does the Luciani triad arise?

1) when removing the cerebral cortex;

2) when removing the sympathetic ganglia

3) when cutting the brain between the superior and inferior colliculi;

4) with damage to the cerebellum.

1406.What symptoms make up the Luciani triad?

1) dermatitis, diarrhea, dementia;

2) manege movements, rocking gait, tremor;

3) goiter, bulging eyes, tachycardia;

4) atony, asthenia, astasia

1407.How does muscle tone change when the cerebellum is removed?

1) does not change;

2) the tone of the extensors increases;

3) first, the tone of the extensors decreases, then the tone of the flexors increases;

4) sharply with the tone of the flexors and extensors decreases

What is tremor?

1) impaired coordination of movements;

2) trembling of the limbs;

3) violation of the alternation of movements;

4) decreased muscle tone.

1409.Which of the following symptoms are observed with damage to the cerebellum?

1) heartburn, belching, drooling;

2) headache, flickering and double vision, chills;

3) diarrhea, dementia, memory loss;

4) sweeping movements. shaking hand and waving at performing a finger-nose test with eyes closed.

1410.Which of the following symptoms are observed with damage to the cerebellum?

1) chills, fever, cough;

2) flickering and double vision;

3) underestimation of the severity of the object, dizziness;

1) long-term memory loss;

1411.How does speech change when the cerebellum is damaged?

1) does not change;

2) becomes fast and illegible;

3) becomes emotional;

4) becomes m monotonous, scanned, slow.

1412.How does handwriting change when the cerebellum is damaged?

1) mills it turns out large, sweeping and clumsy;

2) becomes small and neat;

3) does not change;

4) if the cerebellum is damaged, the ability to write is lost.

What condition occurs when the pathways connecting the reticular formation with the cerebral cortex are cut?

1) excitement;

2)dream;

3) parkensonism;

4) muscle rigidity.

Where is the center of thirst?

1) in the hypothalamus;

2) in the red core;

3) in the medulla oblongata;

4) in the lateral geniculate body.

1441.Where is the center of heat generation

1) in the medial geniculate body;

2)in the gray hillock of the hypothalamus;

3) in the anterior hypothalamus;

4) in the medulla oblongata.

What is dermographism?

1) pathological dilatation of blood vessels during their denervation;

2) mental weakness;

3) a sharp increase in tendon reflexes;

4)a mark on the skin from mechanical irritation.

What is echoencephalography

1)study of the structure of brain tissue using ultrasound;

2) x-ray examination of the skull;

3) recording of brain biopotentials;

4) study of blood supply to the blood vessels of the brain.

Weight of the spinal cord in an adult

1287.Which of the listed structural principles applies to the spinal cord?

1) the principle of unity of analysis and synthesis;

2) the principle of structure;

3) the principle of segmentation;

4) the principle of convergence of reflexes.

1288.What is considered a segment of the spinal cord?

1) a segment of the spinal cord corresponding to one of the sections: cervical, thoracic, lumbar, sacral and coccygeal;

2) a segment of the spinal cord corresponding to one of its sections, except for the coccygeal;

3) a segment of the spinal cord innervating any organ: heart, lungs, liver, etc.;

4) a segment of the spinal cord corresponding to two pairs of roots (right and right).

1289.How many segments of the spinal cord are there in the cervical region?

2) 8;

1290.How many segments of the spinal cord are there in the thoracic region?

1291.How many segments of the spinal cord are there in the lumbar region?

1292.How many segments of the spinal cord are there in the sacral region?

1293.How many segments of the spinal cord are there in the coccygeal region?

1) none;

1294.What is the gray matter of the spinal cord?

1) conducting pathways;

2) accumulation of nerve cells:

3) accumulation of neuron axons;

4) accumulation of neuron dendrites.

1295.What is the white matter of the spinal cord?

1) accumulation of autonomic ganglia;

2) accumulation of nerve cells;

3) accumulation of lymphatic vessels with white milky juice;

4) conducting pathways.

1296. Through which opening does the spinal cord pass into the cranial cavity?

1) through a large gear;

2) through the greater occipital:

3) through the large oval;

4) through the large arachnoid.

1297.What passes through the center of the spinal cord?

1) artery supplying the spinal cord;

2) conductive tracts of the spinal cord;

3) spinal canal:

4) neurons and pathways of the autonomic nervous system.

1298.What neurons lie in the anterior horns of the spinal cord?

1) sensitive;

2) motor:

3) intercalary somatic;

4) intercalary vegetative.

1299.What neurons lie in the dorsal horns of the spinal cord?

1) intercalary vegetative;

2) motor;

3) intercalary somatic;

4) sensitive.

1300.What neurons are located in the lateral horns of the spinal cord?

1) sensitive;

2) there are no neurons in the lateral horns;

3) neurons of the autonomic nervous system;

4) motor neurons.

1301.How many pairs of spinal roots are there?

1302. How many metamers innervate one spinal root?

1303.Where are the spinal ganglia located?

1) along the dorsal spinal roots;

2) along the anterior spinal roots;

3) in the lateral horns of the spinal cord;

4) in the muscular wall of internal organs.

1304.What are the main functions of the spinal cord?

1) reflex and information-conductive;

2) innervation of all skeletal muscles;

3) extero-, intero- and proprioceptive;

4) trophic.

1305.Where is the center of the knee reflex located?

1) in the anterior horns of the 2-4 sacral segments of the spinal cord;

2) in the anterior horns of 2-4 lumbar segments of the spinal cord;

3) in the lateral horns of 2 - 4 sacral segments of the spinal cord;

4) in the lateral horns of the 2-4 thoracic segments of the spinal cord.

1306.Is it possible to assess the level of metabolism by the time of the knee reflex?

1) there is no such dependence;

2) the higher the metabolic rate, the longer the knee reflex time;

3) the higher the metabolic rate, the shorter the knee reflex time;

4) if you know the time of the knee reflex, then you can determine the level of metabolism using the Dreyer formula.

1307.Which of the listed autonomic reflexes are classified as spinal cord reflexes?

1) secretion of the digestive glands, sucking, chewing, swallowing;

2) constriction of peripheral vessels, dilation of the bronchi, sweating, urination, defecation. erection. ejaculation:

3) flexion, scratching reflex, jumping reflex, Philipson reflex;

4) coughing, sneezing, blinking, watery eyes.

1308.Which of the listed somatic reflexes are classified as spinal cord reflexes?

1) scratching reflex, Philipson reflex, contraction reflexes of skeletal muscles;

2) secretion of the digestive glands, sucking, chewing, swallowing;

3) urination, defecation, erection, ejaculation;

4) coughing, sneezing, blinking.

1309.What is the Bell-Magendie law?

1) when the spinal cord is transected, the ability for voluntary movements disappears forever;

2) the dorsal roots of the spinal cord are sensitive, and the anterior ones are motor;

3) when the spinal cord is transected, reflexes disappear, the spinal centers of which are located below the transection site;

4) when the spinal cord is transected, reflexes disappear, the spinal centers of which are located above the transection site.

1310.What is the function of the Gaulle and Burdach bundles located in the posterior columns of the spinal cord?

1) carrying out auditory sensitivity from the opposite half of the body;

2) conducting temperature sensitivity;

3) conducting pain sensitivity;

4) carrying out tactile sensitivity, sense of body position and vibration.

1311.What is the speed of excitation through the Gaulle and Burdach bundles lying in the posterior columns of the spinal cord?

1) 15 - 20 m/s;

1312. What is the function of the Flexig and Gowers bundles located in the lateral columns of the spinal cord?

1) carrying out popriopeytive sensitivity from muscles, tendons, ligaments;

2) conducting pain sensitivity;

3) conducting pain and temperature sensitivity;

4) carrying out tactile sensitivity.

1313.What is the speed of excitation through the Flexig and Gowers bundles lying in the lateral columns of the spinal cord?

1) 15 - 20 m/s;

4) 60 - 70 m/s.

1314.What type of sensitivity is carried out by the lateral spinothalamic tract?

2) pain and temperature sensitivity:

4) deep muscle feeling.

1315.What type of sensitivity is carried out by the ventral spinothalamic tract?

1) tactile sensitivity;

2) pain sensitivity;

3) proprioceptive sensitivity;

4) temperature sensitivity.

1316.Where do the pyramidal paths begin?

1) from the pyramids of the temporal bones;

2) from pyramidal cells of the cerebellum;

3) from pyramidal cells of the cortex;

4) from the Egyptian pyramids.

1317.What do the pyramidal tracts innervate?

1) the muscles of the same half of the body;

2) the muscles of both the same and the opposite half of the body;

3) internal organs below the diaphragm;

4) the muscles of the opposite half of the body.

What is observed when the pyramidal tracts are damaged?

1) paralysis of the muscles of the same side of the body;

2) paralysis of the muscles of the opposite side of the body:

3) paralysis of the secretion of the digestive glands;

4) reduction of heart contractions to 50 per minute.

1318.What structures of the brain is the spinal cord connected through the rubrospinal tract?

1) with the cerebellum, quadrigeminal, red nucleus, motor and subcortical nuclei;

2) with sensorimotor centers of the cerebral cortex;

3) with the limbic system;

4) with the pineal gland and the posterior lobe of the pituitary gland.

1319.What functions are controlled by the brain through the rubrospinal tract?

1) regulates the maturation of red blood cells;

2) regulates lymph formation;

3) regulates muscle tone and coordinates movements;

4) regulates heat generation and heat transfer.

1320.What functions are controlled by the brain through the vestibulospinal tract?

1) regulates tonic reflexes and body position;

2) regulates the tone of the spinal cord;

3) regulates sweating;

4) regulates hematopoiesis and lymphopoiesis.

1321.What structures of the brain is the spinal cord connected through the reticulospinal tract?

1) with the vestibular nuclei;

2) with the cerebellum;

3) with the reticular formation;

4) with the limbic system.

1322.What influence does the reticular formation have on the spinal cord through the reticulospinal tract?

1) regulates sweating;

2) regulates hematopoiesis;

3) regulates the tone of the vascular walls;

4) inhibits and excites motor and interneurons of the spinal cord.

1323.At what level does transection of the spinal cord lead to death?

1) I - III cervical segment;

2) IV lumbar segment;

3) XII thoracic segment;

4) I thoracic segment.

1324.What is the cause of death of an animal with the spinal cord cut off at level I - 111 of the cervical segment?

1) cardiac arrest;

2) paralysis of the diaphragm and intercostal muscles;

3) violation of thermoregulation;

4) violation of the endocrine function of the pancreas and adrenal glands.

1325.How does breathing change after transection of the spinal cord below the IV cervical segment?

1) breathing stops;

2) does not change;

3) the movements of the diaphragm cease;

4) only diaphragmatic breathing is preserved, and the intercostal muscles are paralyzed.

1326.What is the first phase of spinal shock expressed in?

2) in a sharp increase in excitability and strengthening of the reflex functions of the spinal centers, an increase in blood pressure;

3) in a sharp drop in excitability and inhibition of all reflex functions of the spinal centers, a decrease in blood pressure;

4) in a sharp tonic contraction of all skeletal muscles, turning into convulsions.

1327.What is the second phase of spinal shock expressed in?

1) in a sharp decrease in blood pressure and loss of consciousness;

2) in a sharp drop in excitability and inhibition of all reflex functions of the spinal centers;

3) in a sharp tonic contraction of all skeletal muscles, turning into convulsions;

4) in a sharp increase in excitability and strengthening of the reflex functions of the spinal centers, the appearance of “mass” reflexes.

1328.What is the mechanism of the first phase of spinal shock?

1) cessation of innervation of vital organs;

2) respiratory arrest;

3) consequences of bleeding resulting from spinal cord injury;

4) elimination of the exciting influence of the reticular formation on the spinal cord.

1329.What is the mechanism of the second phase of spinal shock?

1) elimination of cortical control over the activity of the spinal cord;

2) elimination of the inhibitory effect of the reticular formation on the spinal cord;

3) eliminating the exciting influence of the reticular formation on the spinal cord;

4) consequences of bleeding resulting from spinal cord injury.

1330. Is the ability to perform voluntary movements restored in the second phase of spinal shock?

2) is restored only on the lower extremities;

3) as a rule, it is not restored;

4) is restored only on the upper limbs.

1331.How long does spinal shock last in humans?

1) 2 weeks,

2) 5 - 7 days;

3) at least 1 month;

1332.Who developed a method for restoring a person’s ability to perform voluntary movements after spinal cord ruptures?

1) academician I.P. Pavlov;

2) academician P.K. Anokhin;

3) athlete V. Dikul;

4) founder of space physiology, academician V.V. Parin.

1333.Where are the first neurons of the first pair of cranial nerves located?

1) in the retina of the eye;

2) in the cerebral cortex;

3) in the lower tuberosities of the quadrigeminal;

4) in the nasal mucosa.

1334.What is the function of the first pair of cranial

1) sensory pathway of visual reception;

2) sensitive pathway of auditory reception;

4) sensory pathway of olfactory reception

1335.Where is the cortical analyzer of olfactory reception located?

1) in the occipital lobe of the cerebral cortex;

2) in the frontal gyrus;

1336.Where are the first neurons of the second pair of cranial nerves located?

1) in the lateral geniculate bodies;

2) in the nasal mucosa;

3) in the occipital lobe of the cerebral cortex;

4) I retina.

1337.What is the function of the second pair of cranial nerves?

1) sensitive pathway of auditory reception;

2) sensory pathway of visual reception;

3) conducting pain reception;

4) sensitive pathway of olfactory reception.

1338.Where is the cortical analyzer of visual reception located?

1) in the anterior central gyrus;

2) in the frontal gyrus;

3) in the calcarine sulcus of the occipital lobe of the cerebral cortex;

4) in the piriform lobe of the cerebral cortex.

1339.Where are the nuclei of the third pair of cranial nerves located?

1) in the medulla oblongata at the bottom of the IV ventricle;

2) in the hypothalamus;

3) in the midbrain:

4) at the bottom of the Sylvian aqueduct

1340. How many nucleoli are there in the nucleus of the third pair of cranial nerves?

1) 5 motor pairs, 1 unpaired vegetative and 1 paired vegetative:

2) 3 motor pairs;

3) 3 pairs of vegetative ones;

4) there are no nucleoli, but there is one paired nucleus for the left and right eyes.

1341.What is the function of 5 pairs of somatic nucleoli of the nucleus of the third pair of cranial nerves?

1) motor nuclei of the muscles of the eyeball;

2) motor nuclei of the facial muscles;

3) sensitive nuclei of the visual analyzer;

4) sensitive nuclei of the auditory apparatus.

1342.What innervates the unpaired autonomic nucleolus of Perlea of ​​the nucleus of the third pair of cranial nerves?

1) lacrimal gland;

2) parotid salivary gland;

3) a mouse that regulates the tension and curvature of the lens;

4) the muscle innervating the width of the pupil lumen.

1343.What do the paired autonomic Yakubovich nucleoli of the nuclei of the third pair of cranial nerves innervate?

1) parotid salivary gland;

2) a mouse that regulates the width of the pupil;

3) a muscle that regulates the tension and curvature of the eye lens;

4) lacrimal gland.

1344.Which of the following applies to the primary subcortical centers of vision?

1) superior colliculus, tuberosity cushion, external geniculate bodies;

2) inferior colliculus, internal geniculate bodies;

3) anterior commissure, gray tubercle;

4) globus pallidus, fornix, posterior commissure.

1345.Where are the nuclei of the fourth pair of cranial nerves located?

1) in the diencephalon;

2) in the pons;

3) in the medulla oblongata;

4) in the midbrain, at the bottom of the Sylvian aqueduct.

1346.What innervates the nucleus of the IV pair of cranial nerves?

1) muscle - sphincter of the pupil, regulating its width;

2) the superior oblique muscle of the eyeball, which rotates it outward and downward;

3) ciliary muscle, which changes the curvature of the lens;

4) chewing muscles.

1347.Which of the following symptoms are observed when the nucleus of the fourth pair of cranial nerves is damaged?

1) complete blindness in both eyes;

2) blindness of the internal visual fields;

3) drooping of the upper eyelid and dilation of the pupil;

4) convergent strabismus, diplopia when looking down.

1348.Where are the nuclei of the V pair of cranial nerves located?

1) in the cerebellopontine angle;

2) in the cerebellum;

4) in the midbrain.

1349.Which of the following innervates the upper and middle branches of the V pair of cranial nerves?

1) upper nasal passages;

2) facial skin. tongue, tooth s, maxillary cavity;

3) skin of the neck, lower lip area;

4) ears, front surface of the neck, root of the tongue.

1350.Which of the following innervates the lower branch of the V pair of cranial nerves?

1) muscles of the cheeks;

2) subcutaneous muscle of the neck;

3) muscles of the upper and lower lips;

4) chewing muscles.

1351.Where are the nuclei of the VI pair of cranial nerves located?

1) in the cerebral cortex;

2) in the cerebellum;

3) in the medulla oblongata at the bottom of the IV ventricle;

4) in the cerebellopontine angle.

1352.What does the VI pair of cranial nerves innervate?

1) facial muscles;

2) muscles of the tongue;

3) rectus externus muscle. abductor of the eyeball outwards:

4) chewing muscles.

1353.Where are the nuclei of the VII pair of cranial nerves located?

1) in the diencephalon;

2) in the cerebellum;

3) in the cerebellopontine angle;

4) in a gray mound.

1354.What does the VII pair of cranial nerves innervate?

1) facial muscles;

2) chewing muscles;

3) the rectus externus muscle, which abducts the eyeball outward;

4) muscles of the tongue.

1355.Where are the nuclei of the VIII pair of cranial nerves located?

1) in the cerebellopontine angle;

2) in the thalamus;

3) in the medulla oblongata at the bottom of the IV ventricle;

4) in the spinal cord,

1356.What is the functional purpose of the VIII pair of cranial nerves?

1) innervation of the facial muscles;

2) orientation of the position of the head and body in space, hearing reception:

3) the path of tactile and pain sensitivity from neck receptors;

4) innervation of the tongue.

1357.Which of the following refers to the primary subcortical hearing centers?

1) inferior colliculus. internal geniculate bodies;

2) superior colliculus, tuberosity cushion, external geniculate bodies;

3) globus pallidus, dentate fascia;

4) gray tubercle, anterior commissure.

1358.Where are the nuclei of the IX pair of cranial nerves located?

1) in the cerebral cortex;

2) in the medulla oblongata at the bottom of the IV ventricle;

3) in the cerebellum;

4) in the subcortex.

1359.What is the functional purpose of the IX pair of cranial nerves?

7) taste nerve of the posterior third of the tongue, sensory nerve of the middle ear and pharynx, motor nerve of the pharyngeal muscles, secretory nerve of the parotid gland;

1) motor nerve of the larynx, trachea, bronchi, esophagus, stomach, small and upper part of the large intestines;

2) secretory nerve of the stomach and pancreas;

3) sensory nerve of the meninges of the external auditory canal.

1360.Where are the nuclei of the X pair of cranial nerves?

1) in length the brain at the bottom of the fourth ventricle;

2) in the cerebellopontine angle;

3) in the cerebral cortex;

4) in the spinal cord.

1361.What does the motor part of the vagus nerve innervate?

1) facial muscles, muscles of the soft palate and tongue;

2) chewing muscles, neck muscles;

3) smooth muscles of the larynx, trachea, bronchi, esophagus, stomach, small and upper part of the large intestines, heart;

4) muscles of the eyeball

1362.Where are the nuclei of the XI pair of cranial nerves located?

1) in the substantia nigra;

2) in the hypothalamus;

3) in the medulla oblongata at the bottom of the IV ventricle;

4) in the telencephalon.

1363.Which pair of cranial nerves innervates the trapezius and sternocleidomastoid muscles, which ensures turning the head to the side and “shrugging” the shoulders?

The spinal cord, like the brain, is covered with meninges (see).

Anatomy (structure). Along its length, the spinal cord is divided into 5 sections, or parts: cervical, thoracic, lumbar, sacral and coccygeal. The spinal cord has two thickenings: the cervical, associated with the innervation of the arms, and the lumbar, associated with the innervation of the legs.

Rice. 1. Cross section of the thoracic spinal cord: 1 - posterior median sulcus; 2 - posterior horn; 3 - side horn; 4 - front horn; 5-central channel; 6 - anterior median fissure; 7 - anterior cord; 8 - lateral cord; 9 - posterior cord.

Rice. 3. Diagram of the location of the spinal cord in the spinal canal (longitudinal section) and the exit of the spinal nerve roots: A - cervical; B - breast; B - lumbar; G - sacral; D - coccygeal.

The spinal cord is divided into gray and white matter. Gray matter is a collection of nerve cells to which nerve fibers approach and depart. In a cross section, the gray matter has the appearance of a butterfly. In the center of the gray matter of the spinal cord is the central canal of the spinal cord, barely visible to the naked eye. In the gray matter, there are anterior, posterior, and in the thoracic region, lateral horns (Fig. 1). The sensory cells of the dorsal horns are approached by the processes of the cells of the spinal ganglia, which make up the dorsal roots; The anterior roots of the spinal cord extend from the motor cells of the anterior horns. The cells of the lateral horns belong to the autonomic nervous system (see) and provide sympathetic innervation of the internal organs, vessels, glands, and the cell groups of the gray matter of the sacral region provide parasympathetic innervation of the pelvic organs. The processes of the cells of the lateral horns are part of the anterior roots.

The roots of the spinal cord exit the spinal canal through the intervertebral foramina of their vertebrae, going from top to bottom over a more or less significant distance. They make a particularly long journey in the lower part of the vertebral column, forming the cauda equina (lumbar, sacral and coccygeal roots). The anterior and posterior roots come close to each other, forming the spinal nerve (Fig. 2). A section of the spinal cord with two pairs of roots is called a spinal cord segment. In total, 31 pairs of anterior (motor, ending in the muscles) and 31 pairs of sensory (coming from the spinal ganglia) roots depart from the spinal cord. There are eight cervical, twelve thoracic, five lumbar, five sacral segments and one coccygeal. The spinal cord ends at the level of the I - II lumbar vertebra, therefore the level of location of the spinal cord segments does not correspond to the vertebrae of the same name (Fig. 3).

White matter is located along the periphery of the spinal cord, consists of nerve fibers collected in bundles - these are descending and ascending pathways; distinguish between anterior, posterior and lateral funiculi.

The spinal cord in a newborn is relatively longer than in an adult, and reaches the third lumbar vertebra. Subsequently, the growth of the spinal cord lags somewhat behind the growth of the spine, and therefore its lower end moves upward. The spinal canal of a newborn is large in relation to the spinal cord, but by 5-6 years the ratio of the spinal cord to the spinal canal becomes the same as in an adult. Growth of the spinal cord continues until approximately 20 years of age, and the weight of the spinal cord increases approximately 8 times compared to the neonatal period.

The blood supply to the spinal cord is carried out by the anterior and posterior spinal arteries and spinal branches arising from the segmental branches of the descending aorta (intercostal and lumbar arteries).

Rice. 1-6. Cross sections of the spinal cord at various levels (semi-schematic). Rice. 1. Transition of the first cervical segment into the medulla oblongata. Rice. 2. I cervical segment. Rice. 3. VII cervical segment. Rice. 4. X thoracic segment. Rice. 5. III lumbar segment. Rice. 6. I sacral segment.

Spinal cord

The anterior concave surface of the medullary cord along its length forms the anterior median fissure. Posteriorly, the surface of the brain is divided by a narrow median sulcus. These lines divide it into symmetrical halves. The motor anterior and sensory posterior nerve roots emerge along the lateral surfaces of the brain. The posterior nerve roots consist of processes of sensory neuron cells. They enter the brain along the posterolateral sulcus. The anterior roots are formed by the axons of motor cells - motor neurons. The processes emerge from the brain substance in the anterolateral sulcus. Before leaving the spinal canal, the sensory and motor nerve roots unite, forming symmetrical pairs of mixed spinal nerves. These nerves, leaving the bone canal between 2 adjacent vertebrae, are directed to the periphery. The length of the bony canal of the spine exceeds the length of the medullary cord. The reason for this is the high rate of bone growth compared to nerve tissue. Therefore, in the lower parts of the spine, the nerve roots are located vertically.

The anterior and posterior spinal arteries, as well as the spinal branches of the segmental branches of the descending aorta - the lumbar and intercostal arteries, supply blood to the structures of the spinal cord and spine.

In the section, you can discern the internal structure of the brain tissue. In the center, shaped like a butterfly or a capital H, there is gray matter surrounded by white matter. Along the entire length of the nerve cord there is a central canal containing cerebrospinal fluid. The lateral projections of the gray matter form gray pillars. In section, the pillars are visible as the posterior horns, formed by the bodies of sensory neurons, and the anterior horns, consisting of the bodies of motor cells. The halves of the “butterfly” are connected by a bridge made of a central intermediate substance. The area of ​​the brain with a pair of roots is called the spinal segment. Humans have 31 spinal segments. The segments are grouped by location: 8 are in the cervical region, 12 in the thoracic region, 5 in the lumbar region, 5 in the sacral region, 1 in the coccygeal region.

Spinal cord: structure and functions, basic physiology

The spinal cord is part of the central nervous system. It is located in the spinal canal. It is a thick-walled tube with a narrow channel inside, somewhat flattened in the anteroposterior direction. It has a rather complex structure and ensures the transmission of nerve impulses from the brain to the peripheral structures of the nervous system, and also carries out its own reflex activity. Without the functioning of the spinal cord, normal breathing, heartbeat, digestion, urination, sexual activity, and any movements in the limbs are impossible. From this article you can learn about the structure of the spinal cord and the features of its functioning and physiology.

The spinal cord is formed in the 4th week of intrauterine development. Usually a woman does not even suspect that she will have a child. Throughout pregnancy, differentiation of various elements occurs, and some parts of the spinal cord completely complete their formation after birth during the first two years of life.

What does the spinal cord look like externally?

The origin of the spinal cord is conventionally determined at the level of the upper edge of the first cervical vertebra and the foramen magnum of the skull. In this area, the spinal cord is gently rebuilt into the brain; there is no clear separation between them. At this point, the so-called pyramidal tracts cross: the conductors responsible for the movements of the limbs. The lower edge of the spinal cord corresponds to the upper edge of the II lumbar vertebra. Thus, the length of the spinal cord is less than the length of the spinal canal. It is this feature of the location of the spinal cord that makes it possible to perform a spinal puncture at the level of the III-IV lumbar vertebrae (it is impossible to damage the spinal cord during a lumbar puncture between the spinous processes of the III-IV lumbar vertebrae, since it is simply not there).

The dimensions of the human spinal cord are as follows: length approx. cm, thickness – 1-1.5 cm, weight – approx.

The spinal cord is divided into several sections according to its length:

In the region of the cervical and lumbosacral levels, the spinal cord is thicker than in other parts, because in these places there are clusters of nerve cells that provide movement of the arms and legs.

The last sacral segments, together with the coccygeal segment, are called the conus spinal cord due to their corresponding geometric shape. The cone passes into the terminal (final) filament. The thread no longer has nerve elements in its composition, but only connective tissue, and is covered with the membranes of the spinal cord. The terminal filum is fixed to the II coccygeal vertebra.

The entire length of the spinal cord is covered with 3 meninges. The first (inner) membrane of the spinal cord is called soft. It carries arterial and venous vessels that provide blood supply to the spinal cord. The next shell (middle) is the arachnoid (arachnoid). Between the inner and middle membranes there is a subarachnoid (subarachnoid) space containing cerebrospinal fluid (CSF). When performing a spinal puncture, the needle must enter exactly this space so that the cerebrospinal fluid can be taken for analysis. The outer shell of the spinal cord is hard. The dura mater continues to the intervertebral foramina, accompanying the nerve roots.

Inside the spinal canal, the spinal cord is attached to the surface of the vertebrae by ligaments.

In the middle of the spinal cord along its entire length there is a narrow tube, the central canal. It also contains cerebrospinal fluid.

From all sides, depressions – fissures and grooves – protrude deep into the spinal cord. The largest of them are the anterior and posterior median fissures, which separate the two halves of the spinal cord (left and right). Each half has additional depressions (grooves). The grooves split the spinal cord into cords. The result is two anterior, two posterior and two lateral cords. This anatomical division has a functional basis - nerve fibers pass through different cords, carrying different information (about pain, about touch, about temperature sensations, about movements, etc.). Blood vessels penetrate into the grooves and crevices.

Segmental structure of the spinal cord - what is it?

How is the spinal cord connected to the organs? In the transverse direction, the spinal cord is divided into special sections, or segments. From each segment there are roots, a pair of anterior ones and a pair of posterior ones, which communicate the nervous system with other organs. The roots emerge from the spinal canal and form nerves that are directed to various structures of the body. The anterior roots transmit information primarily about movements (stimulate muscle contraction), therefore they are called motor roots. The dorsal roots carry information from receptors to the spinal cord, that is, they send information about sensations, which is why they are called sensitive.

The number of segments is the same for all people: 8 cervical segments, 12 thoracic, 5 lumbar, 5 sacral and 1-3 coccygeal (usually 1). The roots from each segment rush into the intervertebral foramen. Since the length of the spinal cord is shorter than the length of the spinal canal, the roots change their direction. In the cervical region they are directed horizontally, in the thoracic region - obliquely, in the lumbar and sacral regions - almost vertically downwards. Due to the difference in the length of the spinal cord and spine, the distance from the exit of the roots from the spinal cord to the intervertebral foramen also changes: in the cervical region the roots are the shortest, and in the lumbosacral region they are the longest. The roots of the four lower lumbar, five sacral and coccygeal segments form the so-called cauda equina. It is this that is located in the spinal canal below the second lumbar vertebra, and not the spinal cord itself.

Each segment of the spinal cord is assigned a strictly defined zone of innervation on the periphery. This zone includes an area of ​​skin, certain muscles, bones, and part of the internal organs. These zones are almost the same for all people. This structural feature of the spinal cord allows one to diagnose the location of the pathological process in the disease. For example, knowing that the sensitivity of the skin in the navel area is regulated by the 10th thoracic segment, if the sensation of touching the skin below this area is lost, we can assume that the pathological process in the spinal cord is located below the 10th thoracic segment. This principle works only taking into account the comparison of zones of innervation of all structures (skin, muscles, and internal organs).

If you cut the spinal cord in a transverse direction, it will not look the same in color. On the cut you can see two colors: gray and white. Gray color is the location of the cell bodies of neurons, and white color is the peripheral and central processes of neurons (nerve fibers). In total, there are more than 13 million nerve cells in the spinal cord.

The bodies of gray neurons are arranged in such a way that they have a bizarre butterfly shape. This butterfly has clearly visible convexities - the front horns (massive, thick) and the rear horns (much thinner and smaller). Some segments also have lateral horns. The region of the anterior horns contains the bodies of neurons responsible for movement, the region of the posterior horns contains neurons that receive sensory impulses, and the lateral horns contain neurons of the autonomic nervous system. In some parts of the spinal cord, the bodies of nerve cells responsible for the functions of individual organs are concentrated. The locations of these neurons have been studied and clearly defined. Thus, in the 8th cervical and 1st thoracic segments there are neurons responsible for the innervation of the pupil of the eye, in the 3rd - 4th cervical segments - for the innervation of the main respiratory muscle (diaphragm), in the 1st - 5th thoracic segments - for regulation of cardiac activity. Why do you need to know this? It is used in clinical diagnosis. For example, it is known that the lateral horns of the 2nd - 5th sacral segments of the spinal cord regulate the activity of the pelvic organs (bladder and rectum). If there is a pathological process in this area (hemorrhage, tumor, destruction due to injury, etc.), a person develops urinary and fecal incontinence.

The processes of neuron bodies form connections with each other, with different parts of the spinal cord and brain, and tend upward and downward, respectively. These nerve fibers, which are white in color, constitute the white matter in cross section. They also form the cords. In the cords, the fibers are distributed in a special pattern. In the posterior cords there are conductors from the receptors of muscles and joints (articular-muscular feeling), from the skin (recognition of an object by touch with closed eyes, sensation of touch), that is, the information goes in an upward direction. In the lateral cords pass fibers that carry information about touch, pain, temperature sensitivity to the brain, to the cerebellum about the position of the body in space, muscle tone (ascending conductors). In addition, the lateral cords also contain descending fibers that provide body movements programmed in the brain. In the anterior cords there are both descending (motor) and ascending (sensation of pressure on the skin, touch) pathways.

The fibers can be short, in which case they connect the segments of the spinal cord with each other, and long, in which case they communicate with the brain. In some places, the fibers may cross or simply move to the opposite side. The crossing of different conductors occurs at different levels (for example, the fibers responsible for the feeling of pain and temperature sensitivity cross 2-3 segments above the level of entry into the spinal cord, and the fibers of the joint-muscular sense go uncrossed to the very upper parts of the spinal cord). The result of this is the following fact: in the left half of the spinal cord there are conductors from the right parts of the body. This does not apply to all nerve fibers, but is especially true for sensory processes. Studying the course of nerve fibers is also necessary to diagnose the location of the lesion in the disease.

Blood supply to the spinal cord

The spinal cord is supplied by blood vessels coming from the vertebral arteries and the aorta. The uppermost cervical segments receive blood from the vertebral artery system (as does part of the brain) through the so-called anterior and posterior spinal arteries.

Along the entire spinal cord, additional vessels carrying blood from the aorta, the radicular spinal arteries, flow into the anterior and posterior spinal arteries. The latter also come in front and rear. The number of such vessels is determined by individual characteristics. Usually there are about 6-8 anterior radicular-spinal arteries, they are larger in diameter (the thickest ones are suitable for the cervical and lumbar enlargements). The inferior radicular-spinal artery (the largest) is called the artery of Adamkiewicz. Some people have an additional radicular-spinal artery coming from the sacral arteries, the Deproge-Gotteron artery. The blood supply zone of the anterior radicular-spinal arteries occupies the following structures: the anterior and lateral horns, the base of the lateral horn, the central sections of the anterior and lateral cords.

The posterior radicular-spinal arteries are an order of magnitude larger than the anterior ones - from 15 to 20. But they have a smaller diameter. The area of ​​their blood supply is the posterior third of the spinal cord in cross section (posterior cords, main part of the posterior horn, part of the lateral cords).

In the system of radicular-spinal arteries there are anastomoses, that is, places where vessels connect with each other. It plays an important role in the nutrition of the spinal cord. If a vessel stops functioning (for example, a blood clot has blocked the lumen), then blood flows through the anastomosis, and the neurons of the spinal cord continue to perform their functions.

The veins of the spinal cord accompany the arteries. The venous system of the spinal cord has extensive connections with the vertebral venous plexuses and veins of the skull. Blood from the spinal cord flows through a whole system of vessels into the superior and inferior vena cava. Where the veins of the spinal cord pass through the dura mater, there are valves that prevent blood from flowing in the opposite direction.

Functions of the spinal cord

Essentially, the spinal cord has only two functions:

Let's take a closer look at each of them.

Reflex function of the spinal cord

The reflex function of the spinal cord is the response of the nervous system to irritation. Have you touched something hot and involuntarily pulled your hand away? It's a reflex. Did something get in your throat and you started coughing? This is also a reflex. Many of our daily actions are based precisely on reflexes that are carried out thanks to the spinal cord.

So, a reflex is a response. How is it reproduced?

To make it clearer, let's take as an example the reaction of withdrawing the hand in response to touching a hot object (1). The skin of the hand contains receptors (2) that perceive heat or cold. When a person touches something hot, an impulse (signaling “hot”) travels from the receptor along the peripheral nerve fiber (3) to the spinal cord. At the intervertebral foramen there is a spinal node in which the body of the neuron (4) is located, along the peripheral fiber of which the impulse arrived. Further along the central fiber from the neuron body (5), the impulse enters the posterior horns of the spinal cord, where it “switches” to another neuron (6). The processes of this neuron are directed to the anterior horns (7). In the anterior horns, the impulse switches to motor neurons (8), responsible for the work of the arm muscles. The processes of motor neurons (9) leave the spinal cord, pass through the intervertebral foramen and, as part of the nerve, are directed to the muscles of the arm (10). The “hot” impulse causes the muscles to contract, and the hand withdraws from the hot object. Thus, a reflex ring (arc) was formed, which provided a response to the stimulus. In this case, the brain did not participate at all in the process. The man pulled his hand back without thinking about it.

Each reflex arc has obligatory links: an afferent link (a receptor neuron with peripheral and central processes), an intercalary link (a neuron connecting the afferent link with the executing neuron) and an efferent link (a neuron that transmits the impulse to the direct executor - an organ, a muscle).

The reflex function of the spinal cord is built on the basis of such an arc. Reflexes are innate (which can be determined from birth) and acquired (formed during life during learning), they are closed at different levels. For example, the knee reflex closes at the level of the 3rd-4th lumbar segments. By checking it, the doctor makes sure that all elements of the reflex arc are intact, including segments of the spinal cord.

It is important for the doctor to check the reflex function of the spinal cord. This is done at every neurological examination. Most often, superficial reflexes are tested, which are caused by touch, line irritation, puncture of the skin or mucous membranes, and deep reflexes, which are caused by the impact of a neurological hammer. Surface reflexes carried out by the spinal cord include abdominal reflexes (stroke irritation of the skin of the abdomen normally causes contraction of the abdominal muscles on the same side), plantar reflex (stroke irritation of the skin of the outer edge of the sole in the direction from the heel to the toes normally causes flexion of the toes) . Deep reflexes include flexion-ulnar, carporadial, extension-ulnar, knee, Achilles.

Conducting function of the spinal cord

The conductor function of the spinal cord is to transmit impulses from the periphery (from the skin, mucous membranes, internal organs) to the center (brain) and vice versa. The conductors of the spinal cord, which make up its white matter, transmit information in the ascending and descending directions. An impulse about an external influence is sent to the brain, and a certain sensation is formed in a person (for example, you are petting a cat, and you have a feeling of something soft and smooth in your hand). This is impossible without the spinal cord. Evidence of this comes from cases of spinal cord injuries, where connections between the brain and spinal cord are disrupted (for example, spinal cord rupture). Such people lose sensitivity; touch does not create sensations in them.

The brain receives impulses not only about touch, but also about the position of the body in space, the state of muscle tension, pain, and so on.

Descending impulses allow the brain to “guide” the body. Thus, what a person intends is carried out with the help of the spinal cord. Did you want to catch up with the leaving bus? The idea is immediately realized - the necessary muscles are set in motion (and you don’t have to think about which muscles need to be contracted and which ones to relax). This is done by the spinal cord.

Of course, the implementation of motor acts or the formation of sensations require complex and well-coordinated activity of all structures of the spinal cord. In fact, you need to use thousands of neurons to get results.

The spinal cord is a very important anatomical structure. Its normal functioning ensures all human life. It serves as an intermediate link between the brain and various parts of the body, transmitting information in the form of impulses in both directions. Knowledge of the structure and functioning of the spinal cord is necessary for diagnosing diseases of the nervous system.

Video on the topic “Structure and functions of the spinal cord”

Scientific educational film from the USSR on the topic “Spinal Cord”

Functions of the spinal cord in the central nervous system - structure and sections, white and gray matter

The organ of the central nervous system is the spinal cord, which performs special functions and has a unique structure. It is located in the spinal column, in a special canal, directly connected to the brain. The functions of the organ are conductive and reflex activity; it ensures the functioning of all parts of the body at a given level, transmits impulses and reflexes.

What is the spinal cord

The Latin name for the spinal cord is medulla spinalis. This central organ of the nervous system is located in the spinal canal. The border between it and the brain passes approximately at the intersection of the pyramidal fibers (at the level of the back of the head), although it is conditional. Inside there is a central canal - a cavity protected by the pia mater, arachnoid and dura mater. Between them is cerebrospinal fluid. The epidural space between the outer shell and the bone is filled with fatty tissue and a network of veins.

Structure

The segmental organization distinguishes the structure of the human spinal cord from other organs. This serves for communication with the periphery and reflex activity. The organ is located inside the spinal canal from the first cervical vertebra to the second lumbar vertebra, maintaining the curvature. From above it begins with an oblong section - at the level of the back of the head, and below - it ends with a conical point, a terminal thread made of connective tissue.

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The organ is characterized by longitudinal segmentation and the significance of its links: the anterior root filaments (axons of nerve cells) emerge from the anterolateral groove, forming the anterior motor root, which serves to transmit motor impulses. The posterior radicular filaments form the dorsal root, conducting impulses from the periphery to the center. The lateral horns are equipped with motor, sensory centers. The roots create the spinal nerve.

Length

In an adult, the organ is 1 cm in length, 1-1.5 cm in width, weighing 35 g. It increases in thickness from bottom to top, reaching its greatest diameter in the upper cervical region (up to 1.5 cm) and the lower lumbosacral region (up to 1 cm). .2 cm). In the chest area the diameter is 1 cm. The organ has four surfaces:

• flattened anterior;
• convex back;
• two rounded side ones.

Appearance

On the anterior surface along the entire length there is a median fissure, which has a fold of the meninges - the intermediate cervical septum. At the back there is a median groove connected to a plate of glial tissue. These slits divide the spinal column into two halves, connected by a narrow bridge of tissue, in the center of which is the central canal. There are also grooves on the sides - anterolateral and posterolateral.

Spinal cord segments

The sections of the spinal cord are divided into five parts, the significance of which depends not on the location, but on the section in which the exiting nerves leave the spinal canal. In total, a person can have five segments:

• cervical part - 8 segments, at its level there is more gray matter;
• chest – 12;
• lumbar – 5, the second region with a large amount of gray matter;
• sacral – 5;
• coccygeal – 1-3.

Gray and white matter

A section of the symmetrical halves reveals a deep median fissure, a connective tissue septum. The inner part is darker - this is the gray matter, and the periphery is lighter - the white matter. In cross-section, the gray matter is represented by a “butterfly” pattern, and its protrusions resemble horns (anterior ventral, posterior dorsal, lateral lateral). Most gray matter is in the lumbar region, less in the thoracic region. The entire surface of the conus medullaris is gray, and along the periphery there is a narrow layer of white.

Functions of gray matter

How is the gray matter of the spinal cord formed? It consists of nerve cell bodies with processes without a myelin sheath, thin myelin fibers, and neuroglia. The basis is multipolar neurons. Cells lie inside in groups called nuclei:

• radicular - axons leave as part of the anterior roots;
• internal - their processes end in synapses;
• fascicular - axons pass to the white matter, carry nerve impulses, and form pathways.

Between the posterior and lateral horns, the gray protrudes in strands into the white, forming a network-like loosening - a reticular formation. The functions of the gray matter of the central nervous system are: transmission of pain impulses, information about temperature sensitivity, closure of reflex arcs, receiving data from muscles, tendons and ligaments. Neurons of the anterior horns are involved in the communication of departments.

White matter functions

A complex system of myelinated, unmyelinated nerve fibers is the white matter of the spinal cord. It includes supporting nervous tissue - neuroglia, plus blood vessels, and a small amount of connective tissue. The fibers are collected in bundles that provide connections between segments. White matter surrounds the gray matter, conducts nerve impulses, and performs mediating activities.

Functions of the spinal cord

The structure and functions of the spinal cord are directly related. There are two important tasks of the organ’s work: reflex and conduction. The first is to perform the simplest reflexes (withdrawing a hand when burned, straightening joints), connections with skeletal muscles. The conduction transmits impulses from the spinal cord to the brain, back along the ascending and descending pathways.

Reflex

The response of the nervous system to irritation consists of a reflex function. This includes withdrawing the hand when receiving an injection, coughing when foreign particles enter the throat. Irritation from the receptors is impulsed into the spinal canal, switches motor neurons that are responsible for the muscles, causing them to contract. This is a simplified diagram of a reflex ring (arc) without the participation of the brain (a person does not think when performing an action).

Reflexes are classified as congenital (breast sucking, breathing) or acquired. The first ones help to identify the correct operation of the elements of the arch and organ segments. They are checked during a neurological examination. The knee, abdominal, and plantar reflexes are mandatory for checking a person’s health. These are superficial types; deep reflexes include flexion-elbow, knee, and Achilles.

Conductor

The second function of the spinal cord is conductive, which transmits impulses from the skin, mucous membranes and internal organs to the brain, in the opposite direction. White matter serves as a conductor, carries information, an impulse about external influences. Due to this, a person receives a certain sensation (a soft, smooth, slippery object). If sensitivity is lost, sensations from touching something cannot be formed. In addition to commands, impulses transmit data about the position of the body in space, pain, and muscle tension.

Which human organs control the functioning of the spinal cord?

The main organ of the central nervous system, the brain, is responsible for the spinal canal and control of the entire functioning of the spinal cord. Numerous nerves and blood vessels act as assistants. The brain has a great influence on the activity of the spinal cord - it controls walking, running, and labor movements. When communication between organs is lost, a person ultimately becomes practically helpless.

Risk of damage and injury

The spinal cord connects all body systems. Its structure plays an important role in the proper functioning of the musculoskeletal system. If it is damaged, a spinal injury will occur, the severity of which depends on the extent of the damage: sprains, ligament ruptures, dislocations, damage to discs, vertebrae, processes - mild, moderate. Severe fractures include displaced fractures and multiple injuries to the canal itself. This is very dangerous and leads to dysfunction of the cords and paralysis of the lower extremities (spinal shock).

If the injury is severe, shock lasts from several hours to months. The pathology is accompanied by impaired sensitivity below the site of injury and dysfunction of the pelvic organs, including urinary incontinence. Computed resonance imaging can detect injuries. To treat minor bruises and damaged areas, medications, therapeutic exercises, massage, and physiotherapy can be used.

Severe variants require surgery, especially to diagnose compression (rupture - cells die instantly, there is a risk of disability). The consequences of spinal cord injury are a long recovery period (1-2 years), which can be accelerated by acupuncture, occupational therapy and other interventions. After a severe case, there is a risk of not fully regaining motor ability, and sometimes of remaining in a wheelchair forever.

Video

The information presented in the article is for informational purposes only. The materials in the article do not encourage self-treatment. Only a qualified doctor can make a diagnosis and make recommendations for treatment based on the individual characteristics of a particular patient.

The spinal cord is the part of the central nervous system located in the spinal canal. The conditional boundary between the medulla oblongata and the spinal cord is considered to be the place of decussion and origin of the first cervical root.

The spinal cord, like the brain, is covered with meninges (see).

Anatomy (structure). Along its length, the spinal cord is divided into 5 sections, or parts: cervical, thoracic, lumbar, sacral and coccygeal. The spinal cord has two thickenings: the cervical, associated with the innervation of the arms, and the lumbar, associated with the innervation of the legs.

Rice. 1. Cross section of the thoracic spinal cord: 1 - posterior median sulcus; 2 - posterior horn; 3 - side horn; 4 - front horn; 5-central channel; 6 - anterior median fissure; 7 - anterior cord; 8 - lateral cord; 9 - posterior cord.

Rice. 2. Location of the spinal cord in the spinal canal (cross-section) and exit of the spinal nerve roots: 1 - spinal cord; 2 - posterior root; 3 - anterior root; 4 - spinal node; 5 - spinal nerve; 6 - vertebral body.

Rice. 3. Diagram of the location of the spinal cord in the spinal canal (longitudinal section) and the exit of the spinal nerve roots: A - cervical; B - breast; B - lumbar; G - sacral; D - coccygeal.

The spinal cord is divided into gray and white matter. Gray matter is a collection of nerve cells to which nerve fibers approach and depart. In a cross section, the gray matter has the appearance of a butterfly. In the center of the gray matter of the spinal cord is the central canal of the spinal cord, barely visible to the naked eye. In the gray matter, there are anterior, posterior, and in the thoracic region, lateral horns (Fig. 1). The sensory cells of the dorsal horns are approached by the processes of the cells of the spinal ganglia, which make up the dorsal roots; The anterior roots of the spinal cord extend from the motor cells of the anterior horns. The cells of the lateral horns belong to (see) and provide sympathetic innervation of the internal organs, vessels, glands, and the cell groups of the gray matter of the sacral region provide parasympathetic innervation of the pelvic organs. The processes of the cells of the lateral horns are part of the anterior roots.

The roots of the spinal cord exit the spinal canal through the intervertebral foramina of their vertebrae, going from top to bottom over a more or less significant distance. They make a particularly long journey in the lower part of the vertebral column, forming the cauda equina (lumbar, sacral and coccygeal roots). The anterior and posterior roots come close to each other, forming the spinal nerve (Fig. 2). A section of the spinal cord with two pairs of roots is called a spinal cord segment. In total, 31 pairs of anterior (motor, ending in the muscles) and 31 pairs of sensory (coming from the spinal ganglia) roots depart from the spinal cord. There are eight cervical, twelve thoracic, five lumbar, five sacral segments and one coccygeal. The spinal cord ends at the level of the I - II lumbar vertebra, therefore the level of location of the spinal cord segments does not correspond to the vertebrae of the same name (Fig. 3).

White matter is located along the periphery of the spinal cord, consists of nerve fibers collected in bundles - these are descending and ascending pathways; distinguish between anterior, posterior and lateral funiculi.

The spinal cord is relatively longer than that of an adult, and reaches the third lumbar vertebra. Subsequently, the spinal cord lags somewhat behind its growth, and therefore its lower end moves upward. The spinal canal of a newborn is large in relation to the spinal cord, but by 5-6 years the ratio of the spinal cord to the spinal canal becomes the same as in an adult. Growth of the spinal cord continues until approximately 20 years of age, and the weight of the spinal cord increases approximately 8 times compared to the neonatal period.

The blood supply to the spinal cord is carried out by the anterior and posterior spinal arteries and spinal branches arising from the segmental branches of the descending aorta (intercostal and lumbar arteries).

Rice. 1-6. Cross sections of the spinal cord at various levels (semi-schematic). Rice. 1. Transition of the first cervical segment into the medulla oblongata. Rice. 2. I cervical segment. Rice. 3. VII cervical segment. Rice. 4. X thoracic segment. Rice. 5. III lumbar segment. Rice. 6. I sacral segment.

Ascending (blue) and descending (red) pathways and their further connections: 1 - tractus corticospinalis ant.; 2 and 3 - tractus corticospinalis lat. (fibers after decussatio pyramidum); 4 - nucleus fasciculi gracilis (Gaull); 5, 6 and 8 - motor nuclei of cranial nerves; 7 - lemniscus medlalis; 9 - tractus corticospinalis; 10 - tractus corticonuclearis; 11 - capsule interna; 12 and 19 - pyramidal cells of the lower parts of the precentral gyrus; 13 - nucleus lentiformis; 14 - fasciculus thalamocorticalis; 15 - corpus callosum; 16 - nucleus caudatus; 17 - ventrulculus tertius; 18 - nucleus ventrals thalami; 20 - nucleus lat. thalami; 21 - crossed fibers of tractus corticonuclearis; 22 - tractus nucleothalamlcus; 23 - tractus bulbothalamicus; 24 - nodes of the brain stem; 25 - sensitive peripheral fibers of the trunk nodes; 26 - sensitive nuclei of the trunk; 27 - tractus bulbocerebellaris; 28 - nucleus fasciculi cuneati; 29 - fasciculus cuneatus; 30 - ganglion splnale; 31 - peripheral sensory fibers of the spinal cord; 32 - fasciculus gracilis; 33 - tractus spinothalamicus lat.; 34 - cells of the posterior horn of the spinal cord; 35 - tractus spinothalamicus lat., its decussation in the white commissure of the spinal cord.