Scheme of sources of blood supply to the spinal cord. Blood supply to the brain and spinal cord meninges and liquor circulation pathways Blood circulation of the spinal cord anatomy

blood supply spinal cord(a synonym for spinal circulation (SC) is carried out by the vertebral artery - a branch of the subclavian artery, as well as from the posterior intercostal, lumbar and lateral sacral arteries of the spinal cord: the former spinal artery, unpaired, lying in the anterior longitudinal fissure of the spinal cord, and the paired posterior spinal artery, adjacent to the posterolateral surface of the spinal cord Numerous branches depart from these arteries and the substance of the brain.

Rice. 5. Scheme of sources of blood supply to the spinal cord

: 1 - aorta; 2 - deep artery of the neck; 3 - anterior radiculomedullary artery of the cervical thickening; 4 - vertebral artery; 5 - intercostal arteries; 6 - upper additional radiculomedullary artery; 7 - large anterior radiculomedullary artery (Adamkevich's artery); 8 - lower additional radiculomedullary artery; 9 - iliac-lumbar artery; dashed lines indicate the boundaries of parts of the spinal cord (I - cervical, II - thoracic, III - lumbar, IV - sacral).

It has been established that several upper cervical segments of the spinal cord supply blood to the anterior and posterior spinal arteries, which branch off from the vertebral arteries. The segments below segments CIII-CIV receive blood from the radiculomedullary arteries. Each such artery, approaching the surface of the spinal cord, dichotomously divides into ascending and descending branches, which connect with similar branches above and below the located radiculomedullary arteries and form the anterior and two posterior arterial anastomotic tracts along the spinal cord (anterior and posterior spinal arteries).

Rice. 6 Schematic representation of the blood supply to a segment of the spinal cord (cross section):

dots indicate the peripheral arterial zone, oblique shading - the central arterial zone, horizontal shading - the area of ​​blood supply to the posterior spinal artery; 1 - area of ​​overlap of the central arterial zone and the zone of blood supply of the posterior spinal artery; 2 - submersible branches; 3 - anterior spinal artery; 4 - posterior spinal artery.

Along the anastomotic tracts, there are areas with oppositely directed blood flow, in particular, in the places where the main trunk of the radiculomedullary artery divides into ascending and descending branches. The number of radiculomedullary arteries includes from 2 to 27 (usually 4-8) anterior arteries and from 6 to 28 (usually 15-20) posterior. There are two extreme types of structure of the vessels supplying the spinal cord - main and loose. With the main type, there is a small number of radiculomedullary arteries (3-5 anterior and 6-8 posterior). With a loose type, there are more such arteries (6-12 anterior and 22 or more posterior). The largest anterior radiculomedullary arteries are located in the middle cervical region spinal cord (artery of the cervical enlargement) and in the lower thoracic or upper lumbar region (artery of the lumbar enlargement, or the large anterior radiculomedullary artery of Adamkevich). AT spinal canal Adamkevich's artery enters next to one of the spinal roots, usually on the left. In 15-16% of cases, there is a large anterior radiculomedullary artery that accompanies the LV or SI root and an inferior accessory radiculomedullary artery that supplies the segments of the epicone and cone of the spinal cord.

The sources of the radiculomedullary arteries at the level of the neck are the deep arteries of the neck (less often the vertebral arteries), at the level thoracic- posterior intercostal arteries, at the level of the lumbar - the lumbar arteries, at the level of the sacrum - the lateral sacral and iliac-lumbar arteries. The anterior radiculomedullary arteries supply blood to the anterior (ventral) 4/5 of the diameter of the spinal cord, and the branches of the posterior radiculomedullary arteries supply blood to the posterior part of the diameter.

The spine and spinal cord are richly supplied with blood, mainly by the metameric arteries, which receive blood from the branches of the aorta.

In the cervical region, such constant sources of blood supply to the vertebrae are the vertebral, deep cervical arteries. In addition, these include non-permanent accessory arteries: the ascending cervical artery and the thyroid trunk. Blood enters the thoracic spine through branches of the intercostal arteries. In the lumbosacral region, the blood supply to the vertebral motor segments and the contents of the spinal canal is provided by the lumbar, middle sacral, ilio-lumbar and lateral sacral arteries. Especially significant is the blood supply to the vertebral segments and the spinal cord LV-SI.

Thus, the blood supply to the vertebrae is usually quite stable, while the blood supply to the intervertebral

discs cease at puberty and the nutrition of the disc tissue is maintained only by diffusion from the parenchyma of the vertebral bodies. This may be one of the reasons for the subsequent development of changes in the structure of the intervertebral discs that form the basis of the spine.

For a long time, the opinion prevailed that there was a dense vascular network in the spinal cord, consisting of three large spinal vessels running longitudinally in relation to it (one anterior and two posterior spinal arteries) and anastomosing with them a large number (theoretically up to 124) anterior and posterior radicular arteries .

Subsequently, it became known that the longitudinal intravertebral, anterior and posterior spinal arteries are discontinuous and are not able to independently provide blood supply to the spinal cord. There was hope that numerous radicular arteries could well cope with this. Back in 1882, the Austrian pathologist A. Adamkevich (Admkiewicz A., 1850-1932) noticed that the blood supply to the spinal cord is not carried out according to a strictly segmental principle. At the same time, the radicular arteries differ significantly in the width of the lumen and in their length. Therefore, only some of them are involved in the blood supply to the spinal cord. Adamkevich described the large anterior radicular artery (Adamkevich's artery). In most people, it is one of the arteries that enters the spinal canal through the intervertebral foramen at the lower thoracic level. Such an artery can be the main source of blood supply to the lower part of the spinal cord (including its lumbar thickening), as well as the cauda equina. In 1889, H. Kadyi suggested that only about 25% of the radicular vessels penetrating the spinal canal participate in the blood supply to the spinal cord.

In 1908, Tanon L., using the method of pouring the thoracic, lumbar and sacral radicular vessels, made sure that "in the human spinal cord, the segmentation of their function is not confirmed", while he noted that most of the radicular arteries participate in the blood supply to the spine does not accept. Depending on the size of the pool of radicular arteries, L. Tanon differentiated them into three categories:

1. the radicular arteries proper, the thinnest, ending within the spinal roots;
2. radicular-shell arteries reaching only the vasculature of the pia mater;
3. radicular-spinal arterial vessels, which are arterial vessels involved in the blood supply to the spine. This classification of the radicular arteries is still recognized as correct in principle.

In 1955, the French Deproges-Gutteron R. described the radicular-spinal artery involved in the blood supply of the epiconus, cone and cauda equina. This artery enters the spinal canal more often with the L5 spinal nerve. Subsequently, it was found that not all people have it and usually takes part in providing blood to the caudal part of the basin of the Adamkevich artery. Thus, it complements the functions of the Adamkiewicz artery, and therefore it became known as the additional anterior radicular artery of Desproges-Hutteron.

A convincing argument in favor of the concept of a non-segmental structure of the spinal cord blood supply system was the clarifying principles of the spinal cord blood supply, established in the course of research by a team of French doctors headed by the neurosurgeon G. Lasorthes (Lasorthes G.). Their results were given in G. Lazorta, A. Gause "Vascularization and hemodynamics of the spinal cord", published in 1973 (Russian translation published in 1977). The authors found that the radicular arteries involved in the blood supply to the spine (radicular-spinal, or radiculo-medullary arteries), having entered the spinal canal, are divided into anterior and posterior branches. The anterior branches involved in the supply of blood to the spinal cord are usually 8-10, while they provide blood supply to 4/5 of the cross section of the spinal cord.

The distribution of the anterior radicular-spinal arterial vessels involved in the blood supply to the spinal cord is uneven and variable. At the same time, most people have anterior radiculo-medullary arteries involved in the blood supply to the cervical segments of the spinal cord, more often than 3, in the upper and middle thoracic regions there are 2-3 of them, at the level of the lower thoracic, lumbar and cauda equina 1-2 arteries. One (the large anterior radicular-medullary artery of Adamkevich, or the artery of the lumbar thickening of Lazorta) is mandatory. It has a diameter of more than 2 mm and enters the spinal canal along with one of the lower thoracic (ThIX, ThX) spinal nerve roots, with 85% on the left and 15% on the right. The second, non-permanent, also unpaired, anterior radicular medullary artery, known as the additional anterior radicular medullary artery of Desproges-Hutteron, enters the spinal canal usually together with the 5th lumbar or 1st sacral spinal nerves, one out of 4 or 5 people has it, that is, in 20-25% of cases.

There are more posterior radicular-spinal arterial vessels than the anterior ones. They take part in the blood supply of 1/5 of the diameter in the posterior part of the spinal cord, including its posterior cords, consisting of conductors of proprioceptive sensitivity (the pathways of Gaulle and Burdach), and the medial sections of the posterior horns. There are about 20 such posterior branches of the radicular medullary arteries, and there are commissural connections between them, so isolated ischemia of the posterior cords is extremely rare.

Thus, when the radicular artery is compressed, ischemia of the corresponding spinal nerve (radiculo-ischemia) occurs, and at the same time, acute or subacute hypalgesia and muscle weakness in the dermatome, myotome and skelerotom corresponding to the affected spinal nerve are possible, which, however, are not always detected due to partial their covering. If the anterior radiculomedullary artery is subjected to compression, the development of radiculomyeloischemia is usually acute with a clinical picture of an almost complete transverse lesion of the spinal nerve, in which only proprioceptive sensitivity pathways are usually preserved below the ischemic focus in the spinal cord, which have better blood supply conditions due to the posterior radicular system. arteries.

In the blood supply to the cervical spine, spinal cord and brain, an important role is played by paired vertebral arteries, which are branches of the subclavian arterial vessels extending from the aorta. First they rise and at the same time move back. Their ex-travertebral section has a length of 5 to 8 cm. At the level of the sixth cervical vertebra, the vertebral arteries, accompanied by para-arterial sympathetic plexuses, enter the channels intended for them - the channels of the vertebral artery, made up of holes in the transverse processes of the vertebrae.

Each of these vertebral arteries is surrounded by a paraarterial autonomic plexus along its entire length. In the process of following these canals of the vertebral arteries, radicular or radicular-medullary arteries depart from them at the level of each intervertebral foramen.

arteries that pass through these openings along with the spinal nerves into the spinal canal. The radicular-medullary arteries play a leading role in the blood supply to the cervical spinal cord. The largest of them is called the artery of the cervical thickening (Lazort).

The main trunks of the vertebral arteries rise to exit from the holes in the transverse processes of the axis; after that, they deviate outwards at an angle of about 45° and enter the homolateral transverse foramina of the atlas (C1 vertebra). Having passed through it, as well as through the atlanto-occipital membrane and the bony foramen magnum, the vertebral arterial vessels enter the cranial cavity, where they give off one branch each, which is the beginning of two posterior spinal arterial vessels. At the same time, each of them at the level of the Cn segment of the spinal cord gives off along the anastomosis, which, merging, form an unpaired anterior spinal artery.

Two posterior and one anterior spinal arterial vessels supply blood mainly to the upper cervical spinal region, and then go down and, at the same time, participate in the blood supply of the spine to the extent possible. However, they are soon fragmented, sometimes interrupted. As a result, these longitudinal spinal arteries usually play an auxiliary role in the blood supply to the spine and spinal cord, while the anterior radicular medullary arteries are the main sources of blood supply to the spinal cord.

The vertebral arteries that have entered the cranial cavity, having approached the posterior edge of the brain bridge, are connected into a single basilar artery. Thus, the vertebrobasilar system is involved in the blood supply to the upper cervical region and provides blood to the brainstem, cerebellum, is involved in the blood supply to the structures of the diencephalon, in particular the hypothalamic region and thalamus, as well as the occipital lobes and the occipito-parietal zone of the cerebral cortex.

The innervation of the vertebral arteries is provided by the paraarterial autonomic plexuses surrounding them, which have a connection with the ganglia of the paravertebral sympathetic chains. Nerve branches also depart from these plexuses, heading to the cervical vertebrae. They participate in the innervation of the periosteum, joint capsules, ligaments and other connective tissue structures of the spine.

To central nervous system function well, it is necessary that the spinal cord be supplied with blood without interruption and in sufficient quantity. With blood supply, the nerve tissues are saturated with oxygen and useful elements. If the blood supply is normal, then the metabolic products are excreted and the metabolism inside the cells occurs. To provide many vital important processes the spinal cord has a rather complex structure. In addition, he is able to be responsible for the correct functioning of muscle contractions, and this greatly affects the movement of the joints. With insufficient blood supply, joint dysfunction may occur. The English physician T. Willis discovered the anterior spinal artery in 1664. This was the beginning of the study of the blood supply to the spinal cord.

Anatomy of the device of the spinal cord

The human spinal cord looks like a thick white tourniquet that is placed in the spinal canal. Its length can reach 45 cm, and its diameter is about 1.5 cm. The average weight of the spinal cord is about 38 g.

Located and protected in a narrow spinal canal. The middle of the spinal cord is made up of gray matter, which covers the element white color. This substance is covered with special membranes that nourish and protect the middle of the spinal cord.

Topography and structure

The spinal cord is arranged and functions quite complicated. Neurosurgeons are seriously studying its development. Ordinary people are very interested in information about the main role of the spinal cord and the topography of blood supply, innervation.

The section of the spinal cord, which is located at the level of the neck and the back of the head, at the site of the opening passes into such an organ as the cerebellum. Where the first two lumbar vertebrae are placed, the spinal cord ends. Its cone is located next to the vertebrae near the lower back. After that comes the so-called terminal thread, which is listed as an atrophied part, otherwise called the “terminal region”. Nerve endings are arranged along this thread. The terminal thread contains such a substance, which contains a small part of the nervous tissue.

In the place where the processes of innervation come out, there are several thickenings: lumbar and cervical. Actually, they are covered by the topography of the spinal cord. Median openings highlight the back and outer surface of the tourniquet.

How is it carried out?

How is the blood supply to the spinal cord? The tourniquet is supplied with blood by the adjacent arteries. The blood supply to the spinal cord is carried out with the help of the carotid and paired vertebral arteries. The main part of the transferred blood falls on the carotid arteries. The anterior artery located along the fissure of the tourniquet is formed by connecting the branches of the arteries of the spine. The arteries located in the anterior opening of the tourniquet are sources of blood supply to the spinal cord. Their placement is behind the tourniquet. These arteries merge with the neck and the posterior lumbar, intercostal and sacral lateral arteries, in the middle of which there is a network of anastomoses. In addition, the blood supply to the spinal cord is also carried out with the help of veins that provide blood outflow.

Anatomy of the blood supply to the spinal cord

The structure of the arteries and vessels of the spinal cord is quite complex, since they are connected by many anastomoses, which is a network that wraps around the surface of the spinal cord. Its scientific name is Vasa corona. Its structure is quite complex. Vessels located perpendicular to the main trunks depart from this ring. They enter the spinal canal through the vertebrae themselves. Between the trunks, in the middle, there are many anastomoses, from which a large network of capillaries usually forms. As a rule, white matter has a less dense network of capillaries than gray matter.

The blood supply to the spinal cord can be briefly described as follows: it is supplied with blood through three spinal arteries, one vertebral artery, segmental arteries and small vessels of the pia mater of the spinal cord.

vertebral artery

The vertebral artery is a large vessel with a lumen of more than 4 mm. It enters the thickness of the spine at the location of the sixth cervical vertebra. This artery saturates some parts of the brain and the upper zone of the spinal cord with blood. That is why the structure of the spinal cord and the brain is usually considered together.

The spinal arteries in the spinal canal are branches extending from one of the structures on the front surface, from which small vessels also depart. They are located in the center of the spinal cord. From there, the blood, which is saturated with oxygen and useful elements, enters the capillaries. They, in turn, fill the nerve cells with blood.

Two spinal arteries follow the posterior surface of the spinal cord, having a smaller lumen than in the anterior artery. The branches departing from them are connected with the branches of the anterior artery. This is how the vascular network enveloping the spinal cord is obtained. The circulatory network is closely connected with the vessels located behind the spinal column. These vessels supply the spinal cord.

The radicular-spinal vessels extending from the branches of the aorta provide additional blood supply to the spinal cord in the regions located below the cervical. They receive blood from the branches of the ascending and vertebral arteries, which are located in the thoracic region. Arteries of the lumbar and intervertebral type send blood to the lower parts of the spinal cord, passing through the openings between the vertebrae. These arteries enter the network that closes the spinal cord.

The dorso-spinal artery is one of the branches of the intercostal artery. It divides into the posterior and anterior radicular arteries. They pass through along with the nerve roots.

The artery, which is located in front of the spinal cord, starts from two branches of the vertebral spinal arteries, which join and form a single trunk. Two posterior spinal arteries run along the dorsal surface of the spinal cord, originating from the vertebral arteries.

The radicular-spinal arteries receive blood from the cervical ascending and vertebral arteries, as well as from the lumbar and intercostal. They regulate the nutrition of most parts of the spinal cord, except for the two upper cervical segments, which are supplied with blood through the vertebral spinal arteries.

Venous system

The spinal cord is very well developed. The most important venous channels receive venous blood from the substance of the spinal cord. They run in the longitudinal direction in the same way as the arterial trunks. The venous channels form a permanent venous tract, connecting at the top with the veins at the base of the skull. The veins of the spinal cord have a connection with the veins of various body cavities through the venous plexuses of the spine.

Areas of blood supply

The spinal cord is supplied with blood from the inside to three different zones. The first zone is a gelatinous substance, Clark's columns, as well as the lateral, anterior and posterior bases of the horns, which represent most of the gray matter. They are located differently for each person. This zone also consists of a part of the white matter, the structures of which are the posterior and anterior cords. They are ventral and deep divisions. Branches of the spinal artery of the anterior view mainly feed the first zone with blood. The second zone consists of the cords and the outer sections of the posterior horns. The Burdach's bundle in this zone is supplied with blood less than the Gaulle's bundle. Branches extending from the posterior spinal artery are of an anastomotic type. It is they who feed the bundles of Gaulle and Burdakh. Sections of the white matter are included in the third zone, which is supplied by the marginal arteries.

Meninges of the spinal cord

The shells perform a shock-absorbing and protective function. The shells of the spinal cord and the brain are very similar in structure, since the brain is a continuation of the spine. The dorsal contains three shells: soft, medium and hard.

The pia mater connects the cerebrospinal fluid and the middle (arachnoid) membrane. It contains blood vessels and closely covers the spinal cord.

The layer of the arachnoid (middle) membrane does not contain blood vessels. It is located between the inner and outer layers of the brain. The middle shell is small in thickness and is able to form. It includes cerebrospinal fluid and nerve roots.

The dura consists of venous tangles and limits the epidural space. It forms the transverse and sagittal sinuses. In this case, the diaphragm of the saddle and the crescent of the cerebellum and cerebrum are formed.

The soft shell covers the spinal cord, on top of it is the middle layer, at the very top is the protective layer.

Functions of the meninges of the spinal cord

The soft shell nourishes the brain with blood and useful elements. It helps to normalize metabolism and supports human performance.

The middle shell helps in metabolism and the formation of hormones. Between the middle and soft layers is a cavity called cerebrospinal fluid. It, in turn, catalyzes the human metabolism and helps to protect the brain as much as possible.

The function of the arachnoid membrane - the layer plays a significant role in the appearance of hormones and the metabolic process in the body, as well as in the neurology of the blood supply to the spinal cord. Functions are associated with the originality of the shell device. Between the soft and arachnoid layer there is a subarachnoid cavity, which contains cerebrospinal fluid. A very important function in the blood supply to the brain and spinal cord is sheath neurology. The cerebrospinal fluid is responsible for the formation of nervous tissue. Connective reticular tissue is the middle layer of the spinal cord. It is very strong and small in thickness. There are no nerves in this sheath.

The hard shell takes an important part in the blood supply, and also, being a natural shock absorber, reduces the mechanical impact on the brain during injuries or movement.

Pachion granulations and cerebrospinal fluid

There are certain features of the blood supply to the spinal cord. Initially, the blood does not go directly to the spinal cord. First it goes through a large number of departments and shells, and only after that it passes into a different state, splitting into useful elements. They, in turn, enter the cerebrospinal fluid, delivering substances to the spinal cord. CSF is the cerebrospinal fluid that circulates between the brain and spinal cord. It is produced by plexuses of blood vessels located in the ventricles of the brain. After filling the ventricles, the cerebrospinal fluid enters the spinal canal. Liquor protects the spinal cord from damage through the depreciation created by it. The cerebrospinal fluid enters the venous sinuses due to granulation occurring in the media.

neurotransmitters

Neurotransmitters play an important role in the blood supply to the spinal cord. They contribute to the release useful substances from the blood, and also produce a special secret through the synthesis of protein and polypeptide compounds. The number and activity of the resulting disorders in the blood circulation is associated with the work of neurotransmitters, since they are located in nerve cells.

Circulatory disorders

There are several causes of impaired blood supply to the spinal cord. Such problems are often various diseases of cardio-vascular system: heart diseases; blood clots in the vessels; vascular atherosclerosis; hypotension (low blood pressure); arterial aneurysm. Atherosclerosis and osteochondrosis are considered fairly common causes of circulatory disorders, which are common in many people, even in young people. In addition, one of the factors of impaired blood supply is the deterioration in the work of the musculoskeletal system. A proper blood supply to the spinal cord is very important, since each vessel in the system plays an important role in the functioning of the spinal cord.

Sometimes there may be a variety of violations. The blood supply to the membranes of the spinal cord can slow down as a result of the appearance of hernias, the growth of tumors and bone tissue, and severe muscle spasms. In addition, squeezing may occur due to previous fractures of the spine. When the vertebral artery is blocked in the cervical region, the blood supply to the membranes of the spinal cord is very severely disturbed. Since this artery constantly provides blood to the human body.

Circulatory failure can also occur due to This problem can occur due to the conduction surgical operation or studies for diagnostic purposes: manual therapy, improper lumbar puncture. Fractures and hemorrhages due to aneurysms are critical.

Hematomyelia

Preventive measures against circulatory disorders of the spinal cord

To improve the circulation of the spinal cord, the following complex is relevant: the prevention of degenerative-dystrophic distortions in the joints and the prevention of atherosclerosis.

Hematomyelia and blood supply pathologies inherited cannot be detected without the help of a specialist doctor. But everyone can influence their lifestyle, attracting more and more people into it. physical activity for healthy joints and blood vessels.

Improving blood supply to the spinal cord and brain

Very often people face the following question: how to restore the blood supply to the spinal cord? Not allowed to apply medications independently without the permission of a medical specialist. To improve blood circulation in the brain, doctors usually prescribe the following drugs:

• Psychostimulants.
• Vasodilator drugs.
• Means against sticking of thrombocytes.
• nootropic drugs.

Medicines that prevent blood clotting

In addition, it is very important to review your diet. For a better blood supply to the spinal cord and brain, it is recommended to use the following products:

• Nuts and sunflower seeds.
• Berries - cranberries, lingonberries.
• Vegetable oil - olive, linseed, pumpkin.
• Fish - salmon, tuna, trout.
• Bitter chocolate.
• Green tea.

Also, in order to prevent dysfunctions in the activity of the brain and spinal cord, it is recommended to avoid a motionless, sedentary lifestyle. Therefore, you should regularly walk, run, play sports, and also do exercises that can activate and improve blood circulation throughout the human body as a whole.

In addition, baths and saunas also help a lot, since the blood supply to the brain and spinal cord improves when the body warms up. Some alternative medicines are also very effective: propolis, periwinkle and many others.

Cerebral circulation has some anatomical and functional features, the knowledge of which is necessary for neurologists to better understand the pathogenesis of many diseases of the nervous system.

Blood supply to the brain

The brain is supplied with arterial blood from two pools: carotid and vertebrobasilar.

The system of the carotid basin in its initial segment is represented by the common carotid arteries. The right common carotid artery is a branch of the brachiocephalic trunk, the left one directly departs from the aorta. At the level of the upper edge of the thyroid cartilage, the common carotid artery branches into the external and internal carotid arteries. Then, through the foramen caroticum, the internal carotid artery enters the canalis caroticum of the pyramid temporal bone. After the artery leaves the canal, it passes along the anterior side of the body of the pterygoid bone, enters the sinus cavernosus of the dura and reaches the place under the anterior perforated substance, where it divides into terminal branches. An important collateral branch of the internal carotid artery is the ophthalmic artery. Branches depart from it, irrigating the eyeball, lacrimal gland, eyelids, forehead skin and, partially, the walls of the nasal cavities. Terminal branches a. ophthalmica - supratrochlear and supraorbital anastomose with branches of the external carotid artery.

Then the artery lies in the Sylviian furrow. The terminal branches of the internal carotid artery are represented by 4 arteries: the posterior communicating artery, which anastomoses with the posterior cerebral artery, which is a branch of the basilar artery; the anterior villous artery, which forms the choroid plexuses of the lateral cerebral ventricles and plays a role in the production of cerebrospinal fluid and blood supply to some nodes of the base of the brain; anterior cerebral artery and middle cerebral artery.

The internal carotid artery connects to the posterior cerebral artery through the posterior communicating arteries. The anterior cerebral arteries are connected to each other through the anterior communicating artery. Thanks to these anastomoses, the arterial circle of Willis, circulus arteriosus cerebry, is formed at the base of the brain. The circle connects the arterial systems of the carotid and vertebrobasilar basins.

Already within the circle of Willis, the anterior cerebral artery gives off several small branches from itself - the anterior perforating arteries - aa. perforante arterios. They pierce the anterior perforated plate and nourish part of the head of the caudate nucleus. The largest of these is the recurrent artery of Geibner, which feeds the anteromedial sections of the head of the caudate nucleus, the putamen, and the anterior two-thirds of the anterior leg of the internal capsule. The anterior cerebral artery itself lies above the corpus callosum and supplies arterial blood to the medial surface of the hemispheres from the frontal pole to the fissura parieto-occipitalis and the anterior two-thirds of the corpus callosum. Also, its branches can enter the orbital region of the base of the brain and the lateral surface of the frontal pole, superior frontal gyrus and paracentral lobule.

The middle cerebral artery is the largest. It lies in the Sylvian sulcus and supplies the entire convexital surface of the hemispheres (with the exception of areas irrigated by the anterior and posterior cerebral arteries) - the lower and middle frontal gyrus, the anterior and posterior central gyrus, the supramarginal and angular gyrus, the rail island, the outer surface of the temporal lobe, the anterior sections occipital lobe. Within the circle of Willis, the middle cerebral artery gives off several thin trunks that pierce the lateral parts of the anterior perforated plate, the so-called aa. perforantes mediales et laterales. The largest of the perforating arteries are aa. lenticulo-striatae and lenticulo-opticae. They supply blood to the subcortical nodes of the hemispheres, the fence, the posterior third of the anterior leg and the upper part of the posterior leg of the internal capsule.

The vertebrobasilar basin in its proximal section is represented by the vertebral arteries that branch off from the subclavian arteries at the level of the transverse process of the VI cervical vertebra (segment V1). Here it enters the opening of its transverse process and rises up along the canal of the transverse processes to the level of the II cervical vertebra (segment V2). Further, the vertebral artery turns backwards, goes to for. transversarium of the atlas (segment V3), passes it and lies down in sulcus a. vertebralis. In the extracranial section, the artery gives off branches to the muscles, bone and ligamentous apparatus of the cervical spine, and takes part in the nutrition of the meninges.

The intracranial vertebral artery is the V4 segment. In this department, branches depart to the dura mater of the posterior cranial fossa, the posterior and anterior spinal arteries, the posterior inferior cerebellar artery, and the paramedian artery. The posterior spinal artery is a steam room. It is located in the posterior lateral groove of the spinal cord and is involved in the blood supply to the nuclei and fibers of the thin and wedge-shaped bundles. Anterior spinal artery - unpaired is formed as a result of the merger of two trunks extending from the vertebral arteries. It supplies the pyramids, the medial loop, the medial longitudinal fasciculus, the nuclei of the hypoglossal nerve and the solitary tract, and the dorsal nucleus. vagus nerve. The posterior inferior cerebellar artery is the largest branch of the vertebral artery and supplies blood to medulla and lower cerebellum. Paramedian branches provide blood supply to the ventral and lateral sections of the medulla oblongata and roots of the IX-XII pairs of cranial nerves.

At the posterior edge of the pons, both vertebral arteries merge to form the main artery - a. basilaris. It lies in the groove of the bridge and on the slope of the occipital and sphenoid bones. Paramedian branches, short envelopes, long envelopes (paired - lower anterior cerebellar and superior cerebellar arteries) and posterior cerebral arteries depart from it. Of these, the largest are the inferior anterior cerebellar, superior cerebellar and posterior cerebral arteries.

The inferior anterior cerebellar artery departs from the main one at the level of its middle third and supplies blood to a piece of the cerebellum and a number of lobes on its anteroinferior surface.

The superior cerebellar artery departs from the upper part of the basilar artery and supplies the upper half of the cerebellar hemispheres, the vermis, and partially the quadrigemina.

The posterior cerebral artery is formed by division of the basilar artery. It nourishes the roof of the midbrain, the brain stem, the thalamus, the lower internal sections of the temporal lobe, the occipital lobe and partially the upper parietal lobule, gives small branches to the choroid plexus of the third and lateral ventricles of the brain.

Between the arterial systems there are anastomoses that begin to function when any one arterial trunk is occluded. There are three levels of collateral circulation: extracranial, extra-intracranial, intracranial.

The extracranial level of collateral circulation is provided by the following anastomoses. With occlusion of the subclavian artery, blood flow is carried out:

 from the contralateral subclavian artery through the vertebral arteries;

 from the homolateral vertebral artery through the deep and ascending arteries of the neck;

 from the contralateral subclavian artery through the internal mammary arteries;

 from the external carotid artery through the superior and inferior thyroid arteries.

With occlusion initial department The vertebral artery flows from the external carotid artery through the occipital artery and the muscular branches of the vertebral artery.

Extra-intracranial collateral circulation is carried out between the external and internal carotid arteries by supraorbital anastomosis. Here the supratrochlear and supraorbital arteries from the system of the internal carotid artery and the terminal branches of the facial and superficial temporal from the system of the external carotid artery are connected.

At the intracranial level, collateral circulation is carried out through the vessels of the circle of Willis. In addition, there is a cortical anastomotic system. It consists of anastomoses on the convexital surface of the hemispheres. Anastomose the terminal branches of the anterior, middle and posterior cerebral arteries (in the region of the superior frontal sulcus, on the border of the upper and middle thirds of the central gyri, along the interparietal sulcus, in the region of the superior occipital, inferior and middle temporal, in the region of the wedge, precuneus and ridge of the corpus callosum) . From the anastomotic network under the pia mater, perpendicular branches extend deep into the gray and white matter of the brain. They form anastomoses in the region of the basal ganglia.

The venous system of the brain takes an active part in blood circulation and cerebrospinal fluid circulation. The veins of the brain are divided into superficial and deep. Superficial veins lie in the cells of the subarachnoid space, anastomose and form a looped network on the surface of each of the hemispheres. They drain venous blood from the cortex and white matter. The outflow of blood from the veins goes to the nearest cerebral sinus. Blood from the outer and medial sections of the frontal, central, and parietal-occipital regions flows mainly into the superior sagittal sinus, and to a lesser extent into the transverse, straight, cavernous, and parietal-basic sinuses. In the deep veins of the brain, the outflow of blood comes from the veins of the choroid plexus of the lateral ventricles, subcortical nodes, visual tubercles, midbrain, pons, medulla oblongata and cerebellum. The main collector of this system is the large vein of Galen, which flows into the straight sinus under the cerebellum. Blood from the superior sagittal and rectus sinuses enters the transverse and sigmoid sinuses and is drained into the internal jugular vein.

Blood supply to the spinal cord

The beginning of the study of the blood supply to the spinal cord dates back to 1664, when the English physician and anatomist T. Willis pointed out the existence of the anterior spinal artery.

According to the length, three arterial basins of the spinal cord are distinguished - cervicothoracic, thoracic and lower (lumbar-thoracic):

 The cervicothoracic basin supplies the brain with blood at the C1-D3 level. In this case, the vascularization of the uppermost parts of the spinal cord (at the level C1-C3) is carried out by one anterior and two posterior spinal arteries, which branch off from the vertebral artery in the cranial cavity. Throughout the rest of the spinal cord, blood supply comes from the system of segmental radiculomedullary arteries. At the middle, lower cervical and upper thoracic levels, the radiculomedullary arteries are branches of the extracranial vertebral and cervical arteries.

 In the thoracic basin, there is the following scheme for the formation of radiculomedullary arteries. The intercostal arteries depart from the aorta, giving off dorsal branches, which in turn are divided into the musculocutaneous and spinal branches. The spinal branch enters the spinal canal through the intervertebral foramen, where it divides into the anterior and posterior radiculomedullary arteries. The anterior radiculomedullary arteries merge to form one anterior spinal artery. The posterior form the two posterior spinal arteries.

 In the lumbar-thoracic region, dorsal branches depart from the lumbar arteries, lateral sacral arteries, and iliac-lumbar arteries.

Thus, the anterior and posterior lumbar arteries are a collection of terminal branches of the radiculomedullary arteries. At the same time, along the course of the blood flow, there are zones with opposite blood flow (at the places of branching and junction).

There are zones of critical circulation where spinal ischemic strokes are possible. These are the junction zones of the vascular basins - CIV, DIV, DXI-LI.

In addition to the spinal cord, the radiculomedullary arteries supply blood to the membranes of the spinal cord, spinal roots, and spinal ganglia.

The number of radiculomedullary arteries varies from 6 to 28. At the same time, there are fewer anterior radiculomedullary arteries than the posterior ones. Most often, there are 3 arteries in the cervical part, 2-3 in the upper and middle thoracic, and 1-3 in the lower thoracic and lumbar.

The following major radiculomedullary arteries are distinguished:

1. Artery of the cervical thickening.

2. Large anterior radiculomedullary artery of Adamkevich. It enters the spinal canal at the level of DVIII-DXII.

3. Inferior radiculomedullary artery of Desproges-Gutteron (available in 15% of people). Included at the LV-SI level.

4. Superior accessory radiculomedullary artery at the DII-DIV level. Occurs with the main type of blood supply.

According to the diameter, three arterial pools of blood supply to the spinal cord are distinguished:

1. The central zone includes the anterior horns, the periependymal gelatinous substance, the lateral horn, the base of the posterior horn, Clark's columns, the deep sections of the anterior and lateral columns of the spinal cord, and the ventral part of the posterior cords. This zone is 4/5 of the entire diameter of the spinal cord. Here, the blood supply comes from the anterior spinal arteries due to the striated submerged arteries. There are two of them on each side.

2. The posterior arterial zone includes the posterior columns, the tops of the posterior horns, and the posterior sections of the lateral columns. Here the blood supply comes from the posterior spinal arteries.

3. Peripheral arterial zone. The blood supply here is carried out from the system of short and long circumflex arteries of the perimedullary vasculature.

The venous system of the spinal cord has a central and peripheral sections. The peripheral system collects venous blood from the peripheral parts of the gray and mainly the peripheral white matter of the spinal cord. It flows into the venous system of the pial network, which forms the posterior spinal or posterior spinal vein. The central anterior zone collects blood from the anterior commissure, the medial and central parts of the anterior horn, and the anterior funiculus. The posterior central venous system includes the posterior cords and posterior horns. Venous blood flows into the striated veins, and then into the anterior spinal vein, located in the anterior fissure of the spinal cord. From the pial venous network, blood flows through the anterior and posterior radicular veins. The radicular veins merge into a common trunk and drain into the internal vertebral plexus or intervertebral vein. From these formations, venous blood flows into the system of the superior and inferior vena cava.

Meninges and cerebrospinal fluid circulation pathways

The brain has three shells: the outermost hard shell - dura mater, under it lies the arachnoid - arachnoidea, under the arachnoid, directly adjacent to the brain, lining the furrows and covering the gyrus, lies the pia mater. The space between the dura mater and the arachnoid is called subdural, between the arachnoid and soft subarachnoid.

Dura mater has two leaves. The outer leaf is the periosteum of the bones of the skull. The inner lamina is connected to the brain. The dura mater has the following processes:

 large crescent process, falx cerebry major, located between both hemispheres of the brain from cristae Galii in front along the sagittal suture to protuberantia occipitalis interna behind;

 small crescent process, falx cerebry minor, goes from protuberantia occipitalis interna to foramen occipitale magnum between the hemispheres of the cerebellum;

 tentorium cerebelli, separates the dorsal surface of the cerebellum from the lower surface of the occipital lobes of the brain;

 the diaphragm of the Turkish saddle is stretched over the Turkish saddle, under it lies an appendage of the brain - the pituitary gland.

Between the sheets of the dura mater and its processes are sinuses - receptacles of venous blood:

1. Sinus sagittalis superior - the superior longitudinal sinus runs along the upper edge of the greater falciform process.

2. Sinus sagittalis inferior - the lower sagittal sinus runs along the lower edge of the large falciform process.

3. Sinus rectus. Sinus sagittalis inferior flows into it. The straight sinus reaches the protuberantia occipitalis interna and merges with the sinus sagittalis superior.

4. In the transverse direction from protuberantia occipitalis interna goes the largest sinus transverses - the transverse sinus.

5. In the region of the temporal bone, it passes into the sinus sigmoideus, which descends to the foramen jugulare and passes into the bulbus superior v. jugulare.

6. Sinus cavernosus - the cavernous sinus is placed on the lateral surface of the Turkish saddle. n are placed in the walls of the sinus. oculomotorius, n. trochlearis, n. ophthalmicus, n. abducens. Inside the sinus passes a. carotis interna. In front of the pituitary gland is the sinus intercavernosus anterior, and behind the sinus intercavernosus posterior. Thus, the pituitary gland is surrounded by a circular sinus.

7. Sinus petrosus superior is located along the upper edge of the pyramid of the temporal bone. It connects sinus cavernosus with sinus transversus.

8. Sinus petrosus inferior lies in the groove of the same name and connects sinus cavernosus with bulbus superior v. jugulare.

9. Sinus occipitalis covers the edges of the foramen magnum and joins the sinus sigmoideus.

The confluence of the sinuses is called confluens sinuum. Blood flows from it into the jugular vein.

The arachnoid is located between the dura and pia mater. On both sides it is lined with endothelium. The outer surface is loosely connected to the dura mater by cerebral veins. The inner surface faces the pia mater, is connected to it by trabeculae, and above the convolutions is tightly fused with it. This is how cisterns are formed in the area of ​​the furrows.

The following tanks are distinguished:

 cisterna cerebello-oblongata, or a large cistern of the brain, is located between the lower surface of the cerebellum and the dorsal surface of the medulla oblongata;

 cisterna fossae Silvii - located in the region of the Sylvius furrow;

 cisterna chiasmatis - located in the region of the optic chiasm;

 cisterna interpeduncularis - located between the legs of the brain;

 cisterna pontis - located on the lower surface of the pons;

 cisterna corporis callosi - located along the dorsal surface of the corpus callosum;

 cisterna ambiens - located between the occipital lobes of the brain and the upper surface of the cerebellum;

 cisterna terminalis, dural sac from level LII, where the spinal cord ends to SII-SIII vertebrae.

All cisterns communicate with each other and with the subarachnoid space of the brain and spinal cord.

Pachion granulations are ectropions of the arachnoid membrane, pushed into the lower wall of the venous sinuses and the skull bones. This is the main place for the outflow of cerebrospinal fluid into the venous system.

The pia mater is adjacent to the surface of the brain, goes into all the furrows and crevices. Richly supplied with blood vessels and nerves. In the form of a double-folded sheet, it penetrates into the cavity of the ventricles and takes part in the formation of the choroid plexuses of the ventricles.

The blood supply to the spinal cord is provided by the anterior and paired posterior spinal arteries, as well as the radicular-spinal arteries.

Located on the anterior surface of the spinal cord, the artery originates from two vertebral arteries and branches (called the spinal arteries) that extend from the intracranial part, which soon merge and form a common trunk running down along the anterior sulcus of the ventral surface of the spinal cord.

Two posterior spinal arteries, originating from the vertebral arteries, run along the dorsal surface of the spinal cord directly at the posterior roots: each artery consists of two parallel stems, one of which is located medially and the other is lateral to the posterior roots.

The spinal arteries from the vertebral arteries supply blood to only 2-3 upper cervical segments, while the rest of the spinal cord is nourished by the radicular-spinal arteries, which in the cervical and thoracic regions receive blood from the branches of the vertebral and ascending cervical arteries (subclavian artery system) , and below - from the intercostal and lumbar arteries extending from the aorta. The dorso-spinal artery departs from the intercostal artery and divides into the anterior and posterior radicular-spinal arteries. The latter, having passed through the intervertebral foramen, go along with the nerve roots. Blood from the anterior radicular arteries enters the anterior spinal artery, and from the posterior - into the posterior spinal artery.

The anterior radicular arteries are smaller than the posterior ones, but they are larger. The number of arteries varies from 4 to 14 (usually 5-8). In the cervical region, in most cases there are 3. The upper and middle parts of the thoracic spinal cord (from D3 to D8) are fed by 2-3 thin anterior radicular arteries.

In some cases, in addition to Adamkevich's artery, small arteries are found that enter from the VII, VIII or IX root, and an artery that enters from the V lumbar or I sacral root, supplying the cone and epicone of the spinal cord.

A large number of “central arteries” depart from the anterior spinal artery at a right angle, which pass along the anterior spinal sulcus and, near the anterior gray commissure, enter the substance of the spinal cord either in the right or in the left half of it. The central arteries supply the anterior horns, the base of the posterior horns, Clark's columns, the anterior columns, and most of the lateral columns of the spinal cord. Thus, the anterior spinal artery supplies approximately 4/5 of the diameter of the spinal cord.

The branches of the posterior spinal arteries enter the region of the posterior horns and, in addition to them, feed almost entirely the posterior columns and a small part of the lateral columns.

Both posterior spinal arteries are connected to each other and to the anterior spinal artery using a horizontal arterial trunk,

The spinal cord has a highly developed venous system. The veins that drain the anterior and posterior sections of the spinal cord have a "watershed" approximately in the same place as the arteries. The main venous channels, which receive the blood of the veins from the substance of the spinal cord, run in the longitudinal direction, similarly to the arterial trunks. At the top, they connect with the veins of the base of the skull, forming a continuous venous tract. The veins of the spinal cord also have a connection with the venous plexuses of the spine, and through them - with the veins of the body cavities.