Subclavian artery and its pathologies. The structure of the right and left subclavian arteries The continuation of the subclavian artery is

The subclavian artery is one of the main human arteries that feeds the head, upper limbs and upper body of a person. The subclavian artery is paired, that is, there is a right and left subclavian artery. For prevention, drink Transfer Factor. They begin in the anterior mediastinum. The right one originates from the brachiocephalic trunk, and the left one - directly from the aortic arch. Therefore, the left subclavian artery is longer than the right, by about 4 cm.
The artery forms an arch convex upwards, enveloping the dome of the pleura. Then, through the upper aperture of the chest, it enters the neck, leads to the interstitial space, where it lies in the same groove of the first rib and below the lateral edge of this rib passes into the axillary cavity and continues like the axillary artery.
The walls of the subclavian artery consist of three membranes: internal, middle and external. The inner shell is formed from the endothelium and the pidendothelial layer. The middle shell consists of smooth muscle cells and elastic fibers, the ratio of which to each other is approximately the same. External - the shell is formed by loose fibrous connective tissue, which contains bundles of smooth myocytes, elastic and collagen fibers. It contains vessels of blood vessels that provide trophic function.
In the subclavian artery, three sections are topographically distinguished: the first - from the place of origin to the interstitial space, the second - in the interstitial space, and the third - from the interstitial space to the upper opening of the axillary cavity. In the first section, three branches depart from the artery: the vertebral and internal thoracic arteries, the thyroid trunk, in the second section - the costocervical trunk, and in the third - sometimes the transverse artery of the neck.
The vertebral artery, whose normal lumen is 1.9 mm–4.4 mm, is considered a branch of the subclavian artery. The vertebral artery is the most significant of the branches of the subclavian artery. It starts from its upper surface, flows into the transverse foramen of the sixth cervical vertebra and lies in the canal, which arose due to the holes in the transverse processes of the cervical vertebrae. The vertebral vein runs along with the artery. From the transverse opening of the first cervical vertebra, the vertebral artery emerges and goes in its groove. Having passed the posterior atlanto-occipital membrane and the dura mater, the artery then lies through the foramen magnum and the posterior cranial fossa. Here begins its intracranial part. Behind the pons of the brain, this artery joins with a similar artery on the opposite side, forming the basilar artery, which is unpaired. Continuing its path, the basilar artery is adjacent to the basilar groove and the lower surface of the bridge at its anterior edge.
In the cranial cavity, the following depart from the vertebral artery: the anterior spinal artery - right and left, the paired posterior spinal artery and the posterior inferior cerebellar artery, which branches on the lower surface of the cerebellar hemisphere.

The human circulatory system is a complex scheme of intricately woven veins, arteries and many capillaries. The subclavian artery is a paired and very large vessel, belongs to the arteries of the great circle. It receives blood from the aortic arch and brachiocephalic trunk and supplies nutrients to the back of the head, part of the spinal cord located in the cervical region, and the cerebellum. Also, the blood from this vessel supplies oxygen to the upper limbs, shoulder girdle and some parts of the peritoneum and chest.

Anatomy

This artery is a convex vessel in the form of an arc located in the anterior mediastinum. Heading up the chest laterally, the vessel goes around the pleura and is superimposed on the upper part of the lung. The topography of the subclavian artery, relative to the neck area, contributes to the supply of oxygen to the cervical muscles and the occipital part of the head.

The vessel is located on the surface and is visible next to the brachial plexus of nerves. The anatomy of the subclavian artery makes it possible to use it for the administration of medications, and also, with heavy bleeding, there is an excellent chance to prevent unpleasant consequences.

Departing from the brachial plexus, the vessel bends over the rib. Here a groove of the subclavian artery is formed, which extends under the clavicle and rises into the armpit. In this area, the vessel passes into the axillary artery. Having passed the armpit, the artery enters the shoulder and becomes the brachial. In the region of the elbow joint, the subclavian artery diverges into the ulnar and radial arteries.

Main branches

The left subclavian artery, like the right one, is very large and is part of the systemic circulation. On its way through the body, it gives off several branches through which blood passes to supply oxygen and nutrients to the internal organs, skin integuments in various parts of the body.

At certain points, this vessel diverges into five branches.

Internal mammary artery

This vessel departs in the region of the pleural dome from the main artery. It passes between the intrathoracic fascia and the pleura, heading towards the lower part of the sternum.

In turn, the thoracic internal artery is divided into:

mediastinal branch;
Tracheal;
perforating;
thymus;
bronchial;
Anterior intercostal;
Pericardiodiaphragmatic;
Upper epigastric;
Muscular-diaphragmatic.

vertebral artery

This vessel originates a few millimeters medial to the anterior edge of the scalene muscle, in the interscalene space. The anterior part of the artery is covered by the inferior supraclavicular thyroid vessel and the carotid artery.

This branch from the subclavian artery is one of the largest and discards the following branches:

Posterior inferior cerebellar;
villous;
Posterior, anterior spinal;
Meningeal.

thyroid trunk

This vessel has a length of 0.5-1.5 cm. It branches off from the subclavian artery in the region of the anterior scalene muscle.

As well as other branches, it is divided into several arteries extending from it:

Ascending cervical;
Superficial cervical;
lower thyroid;
Suprascapular.

Costo-cervical trunk

This large vessel departs from the wall of the subclavian artery to the small axillary vessel in the interstitial space and is located at the first rib, at its head.

The trunk in its course is divided into the following branches of the large subclavian artery:

cervical transverse;
Intercostal overhanging;
Neck deep;
Surface.

Basilar artery

This vessel is formed as a result of the connection of two vertebral arteries in the region of the posterior edge of the bridge.

The following branches of the blood channels depart from it:

Posterior cerebral;
Artery of the labyrinth;
Superior cerebellar;
pontine artery;
Inferior anterior cerebellar;
Mid-brain.

Departments and functions

The superficial location of this vessel is very convenient for puncture. Subclavian artery catheterization is also often performed in this area of the neck. Specialists prefer this site, because it is accessible, due to its anatomical features, the artery has a more than suitable lumen diameter, a stable position.

During catheterization, the delivered catheter will not come into contact with the walls of the vessel, and the drug that will be injected through it will quickly reach the goal, actively influencing hemodynamics.

The main divisions of the subclavian artery are three sections:

Interstitial space. The vertebral and steam arteries depart from it;
Costo-cervical trunk;
Branching of the transverse cervical artery.

The subclavian vessel, located in the 1st section, passes into the skull. Its function is to supply blood to the brain, neck muscles. The internal thoracic artery supplies blood to the thyroid gland, diaphragm, and bronchi. It is divided into the overhanging intercostal vessel and other adjacent arteries.

Palpation

Probing and examination of the subclavian artery (palpation) is carried out according to the apical impulse palpation scheme, that is, with three or two fingers. First, the arteries are examined at the edge of the sternocleidomastoid muscles above the collarbones. Then a transition is made to the region of the depth of the subclavian fossae under the collarbones at the edges of her deltoid muscles. The study is carried out very carefully, by applying fingers and pressing on soft tissues in the area of the externally examined area.

In a healthy person who is at rest, the subclavian arteries will not be palpated, or their pulsation will be barely perceptible. This is due to their sufficient depth of occurrence. You can feel a strong pulsation in people with poor development of the muscle tissue of the shoulder and neck, after physical exertion, emotional upheaval, as well as in asthenic patients.

With the pathology of the subclavian artery, its pulsation is clearly manifested. This phenomenon can be observed in aortic insufficiency and hyperkinetic type of hemodynamics. With an aneurysm of the vessels, a pulsation is usually palpated in the supraclavicular area, slightly limited (2-3 cm). The weakening of the pulsation of these arteries can be accurately assessed by probing them simultaneously using both hands. This may be due to a violation of their patency (thrombosis, compression, atheromatosis) or, if there is an anomaly, an aberrant right subclavian artery.

Possible pathologies

The most common disease that affects the subclavian artery and its branches is stenosis. This pathology develops due to the presence of atherosclerosis or thrombosis. The disease can be both congenital and acquired. People who are fond of smoking, overweight and suffering from diabetes are at risk of getting stenosis.

Also, quite often, stenosis develops against the background of impaired metabolism, due to neoplasms and a long-term inflammatory process. In the first course of the disease in an acute form, a significant decrease in blood flow is possible, which can cause a stroke or ischemia. With stenosis of the subclavian arteries, the majority of patients complain of severe pain, which increases with exertion.

Treatment Method

A disease such as stenosis can be treated with medication, in its mild form, interventionally and surgically. But the main methods of therapy, according to experts, are shunting and stenting. These treatments have been used for a very long time and have an excellent success rate for the procedure.

Shunting

If stenosis is detected in the 2nd section of the artery, shunting is indicated. If the ipsilateral common carotid artery is damaged, a crossover bypass is preferred. This method of surgical intervention does not injure the tissues and organs of the patient, does not require the use of general anesthesia, takes a little time and does not cause serious postoperative complications. Before it is carried out, it is necessary to conduct an ultrasound scan.

If the subclavian large artery is damaged on the left or on both sides, then its reconstruction in the affected area will first be necessary. If the operation is unsuccessful, re-intervention is difficult. Contralateral lesions of the subclavian vessels require preliminary elimination of the steel syndrome, only then can shunting be started. Reconstruction of the damaged section of the artery is possible only with non-regressive vertebrobasilar insufficiency. All surgical interventions, be it shunting, stenting, and others, are not carried out without a complete preliminary examination of the patient and an accurate diagnosis.

Stenting

This method is indicated for patients who have a hypersthenic physique and a special topography of their subclavian arteries. The first section of the artery in such people is difficult to grope. The method of stenting is very convenient and significantly prevails over surgical abdominal intervention. With this gentle process, there is no change in the arteries, and the tissues of the body are not injured.

With the help of stenting, doctors increase the lumen of the affected vessel. For this, a catheter and a balloon-shaped stent are used. All procedures are performed under local anesthesia. The movement of the stent along the artery occurs under the control of an experienced specialist, who regulates its location. Having reached the site of narrowing, the device opens. If the stent is not open enough, angioplasty is performed. The total operation time is no more than 2 hours.

Complications

Although such operations cannot be called complex, they still have a rather long rehabilitation period. After stenting, it is recommended to take painkillers, since the places of punctures and incisions in soft tissues and arteries can hurt. Postoperative complications are extremely rare, since before the procedure the patient undergoes a complete examination of the whole body (ultrasound, etc.). But still, the reaction of the body under certain circumstances can be unpredictable (for example, if there is a defect - an aberrant subclavian artery).

After stenting, the patient may experience:

Allergy to drugs;
Temperature increase;
Headache;
wound infection;
Air embolism;
Stent migration;
Bleeding at the puncture site;
arterial thrombosis;
neurological complications.

Interventional therapy of stenosis and other diseases of the subclavian arteries by stenting and agioplasty is a modern minimally invasive measure. Such effective procedures are carried out in a very short time and do not require long-term hospitalization. It is enough to pre-pass an ultrasound and pass the necessary tests.

Question:

I kindly ask you to answer me this question. I did an ultrasound scan, the diagnosis was atherosclerosis of the right subclavian artery (the intima-media complex was thickened up to 1.5 mm at the mouth of the right subclavian artery). I am very concerned. Tell me if this is dangerous and what needs to be done to stop this process? I look forward to your reply. Thank you in advance.

Answer:

Thickening of the intima is not a cause for concern. However, it is advisable to check the level of cholesterol in the blood.

SUBCLAVIAN STEAL SYNDROME honey.

Subclavian steal syndrome - cessation of blood flow along the branches of the proximal subclavian artery, which supplies blood to the upper limbs, as a result of which blood enters this section from the system of the arterial circle of the brain, which leads to ischemia of the brain tissue; maximum manifestations - during physical activity.

Etiology

Damage to the vascular wall itself - atherosclerosis (95% of cases), nonspecific arteritis, specific arteritis (in particular, syphilitic)

Pathological tortuosity of arteries, displacement of their mouths, anomalies in the development of the aortic arch

Extravasal factors that contribute to compression of the vessel from the outside (additional cervical ribs, anterior scalene syndrome, etc.).

Clinical picture

Dizziness or lightheadedness (especially on exertion), possible blurred vision, hemianopia and ataxia

Muscle weakness in the limb on the side of the lesion

Absence or weakening of the pulse on the side of the lesion.

Diagnostics

Non-invasive measurement of blood pressure in the upper limbs (the difference in unilateral lesions reaches more than 20 mm Hg)

Differential Diagnosis

Subclavian artery occlusion

Occlusion of the subclavian artery is a complete closure of the lumen of the subclavian artery, accompanied by insufficient blood supply to the brain and upper limbs. In vascular surgery and cardiology, stenosis and occlusion of the carotid arteries are more common (54-57%). Occlusion of the first segment of the subclavian artery, according to different authors, is found in 3-20% of cases; while in 17% of cases there are concomitant lesions of the vertebral artery and/or the second segment of the subclavian artery. Bilateral occlusion of the subclavian artery occurs in 2% of cases; the second and third segments of the subclavian artery are affected much less frequently and have no independent significance in the pathogenesis of cerebrovascular ischemia. Occlusion of the left subclavian artery occurs 3 times more often than the right one.

The subclavian artery is a paired branch of the aortic arch, consisting of the right and left subclavian arteries that supply blood to the upper limbs and neck. The right subclavian artery originates from the brachiocephalic trunk, the left directly departs from the aortic arch. Topographically, 3 segments are distinguished in the subclavian artery. The vertebral artery departs from the first segment (supplies the spinal cord, muscles and dura mater of the occipital lobes of the brain), the internal thoracic artery (provides blood supply to the pericardium, main bronchi, trachea, diaphragm, sternum, anterior and superior mediastinum, pectoral muscles, rectus abdominis ) and the thyroid trunk (blood supply to the thyroid gland, esophagus, pharynx and larynx, muscles of the scapula and neck).

The only branch of the second segment of the subclavian artery (costocervical trunk) supplies blood to the muscles of the neck, cervical and beginning of the thoracic spine. The branch of the third segment (the transverse artery of the neck) mainly supplies blood to the muscles of the back.

Causes of subclavian artery occlusion

The main causes of subclavian artery occlusion are obliterating atherosclerosis. obliterating endarteritis. Takayasu's disease (nonspecific aortoarteritis), post-embolic and post-traumatic obliterations.

Atherosclerosis is the most common cause of occlusive lesions of the aorta and its branches. At the same time, atherosclerotic plaques protruding into the lumen of the vessel are formed in the intima of the arteries. As a result of subsequent sclerosis and calcification of the vascular wall in the area of the affected area, the deformation and stenosis of the vessel lumen gradually progress, which determine the ischemic stage of atherosclerosis. In some cases, atherosclerotic lesions can be complicated by thrombosis, leading to acute ischemia and necrosis of the blood-supplying organ (thrombo-necrotic stage of atherosclerosis). Additional risk factors for atherosclerosis are smoking, arterial hypertension. hypercholesterolemia. diabetes. cardiovascular disease.

Obliterating endarteritis, as the cause of occlusion of the subclavian artery, is characterized by inflammatory changes in the walls of the arteries, pronounced hyperplastic processes leading to thrombosis and obliteration of the vessels.

Takayasu's disease, named after a Japanese ophthalmologist. who first described it, can proceed with damage to the branches of the aortic arch, the development of aortic aneurysms. coarctation syndrome, aortic insufficiency. renovascular hypertension, abdominal ischemia, pulmonary artery disease, general inflammatory reaction. Nonspecific aortoarteritis most often leads to occlusion of the distal (second or third) segments of the subclavian arteries.

The development of occlusion of the subclavian artery can be facilitated by extravasal compression factors: scars and tumors of the mediastinum. curvature of the cervicothoracic spine, cervical osteochondrosis. neck injuries, fracture of the clavicle and 1st rib with the formation of excessive bone callus, chest trauma. In some cases, occlusion of the subclavian artery is the result of congenital anomalies of the aortic arch and its branches.

In the pathogenesis of disorders arising from occlusion of the subclavian artery, the main role belongs to ischemia of the tissues supplied by the affected branch. Thus, when the proximal segment of the subclavian artery is occluded, blood enters its distal segment and upper limb through the vertebral artery, which leads to depletion of the blood supply to the brain. This phenomenon, especially manifested during physical exertion, is called steel syndrome or "subclavian steal syndrome".

The rapid development of occlusion of the subclavian artery, associated with associated thrombosis, leads to cerebral ischemia - acute ischemic stroke.

Symptoms of subclavian artery occlusion

Occlusion of the first segment of the subclavian artery is manifested by one of the characteristic syndromes or their combination: vertebrobasilar insufficiency. upper limb ischemia, distal digital embolism, or coronary-mammary-subclavian steal syndrome.

Vertebrobasilar insufficiency with occlusion of the subclavian artery develops in approximately 66% of cases. The clinic of vertebrobasilar insufficiency is characterized by dizziness. headaches, cochleovestibular syndrome (hearing loss and vestibular ataxia), visual disturbances due to ischemic optic neuropathy.

Ischemia of the upper limb with occlusion of the subclavian artery is observed in approximately 55% of patients. During ischemia, 4 stages are distinguished:

I - stage of full compensation. Accompanied by increased sensitivity to cold, chilliness, numbness, paresthesia, vasomotor reactions. II - stage of partial compensation. Circulatory failure develops against the background of a functional load on the upper limbs. It is characterized by transient symptoms of ischemia - weakness, pain, numbness, coldness in the fingers, hand, muscles of the forearm. There may be transient signs of vertebrobasilar insufficiency. III - stage of decompensation. Circulatory failure of the upper extremities occurs at rest. It proceeds with constant numbness and coldness of the hands, muscle hypotrophy, a decrease in muscle strength, and the inability to perform fine movements with the fingers. IV - stage of development of ulcerative-necrotic changes in the upper limbs. There is cyanosis, swelling of the phalanges, cracks, trophic ulcers. necrosis and gangrene of the fingers.

Stage III and IV ischemia with occlusion of the subclavian artery is rarely detected (6-8% of cases), which is associated with a good development of the collateral circulation of the upper limb.

Distal digital embolism with occlusion of the subclavian artery of atherosclerotic origin, it occurs in no more than 3-5% of cases. In this case, ischemia of the fingers occurs, accompanied by severe pain, blanching, coldness and impaired sensitivity of the fingers, and occasionally gangrene.

In patients who have previously undergone mammary coronary bypass surgery. in 0.5% of cases may develop coronary-mammary-subclavian steal syndrome. In this case, hemodynamically significant stenosis or occlusion of the first segment of the subclavian artery can aggravate myocardial ischemia and cause myocardial infarction.

Diagnosis of occlusion of the subclavian artery

Occlusion of the subclavian artery can be suspected during the physical examination. With a difference in blood pressure in the upper limbs> 20 mm Hg. Art. should think of critical stenosis, and >40 mm Hg. Art. - about occlusion of the subclavian artery. The pulsation of the radial artery on the affected side is weakened or absent. With occlusion of the subclavian artery, a systolic murmur is heard in the supraclavicular region in 60% of patients.

Ultrasound or duplex scanning of the vessels of the upper limb helps to detect occlusion of the subclavian artery in 95% of cases. The criteria for occlusion of the first segment of the subclavian artery are the vertebral-subclavian steal syndrome, the presence of collateral blood flow in the distal subclavian artery, the presence of retrograde blood flow in the vertebral artery, and a positive reactive hyperemia test.

Peripheral arteriography allows you to finally determine the diagnosis of subclavian artery occlusion and treatment tactics. With the help of radiopaque angiography, the level of occlusion of the subclavian artery, retrograde blood flow through the vertebral arteries, the extent of obliteration, the presence of post-stenotic aneurysms, etc. are revealed.

Treatment and prognosis of subclavian artery occlusion

Subclavian artery occlusion, accompanied by subclavian-vertebral steal syndrome, symptoms of vertebrobasilar insufficiency, ischemia of the upper limb, is an indication for angiosurgical intervention.

Reconstructive interventions for occlusion of the subclavian artery are divided into:

plastic (endarterectomy, resection with prosthetics, implantation of the subclavian artery into the common carotid); shunting (aorto-subclavian bypass, carotid-subclavian bypass, carotid-axillary bypass, cross subclavian-subclavian bypass); endovascular (dilatation and stenting of the subclavian artery, laser or ultrasound recanalization of the subclavian artery).

Due to the high sensitivity of the brain to ischemia and the complexity of the anatomy of the neck, in the surgical treatment of occlusion of the subclavian artery, specific complications are possible - intraoperative or postoperative stroke; damage to peripheral nerves with the development of Horner's syndrome, plexitis, paresis of the dome of the diaphragm, dysphagia; cerebral edema, pneumothorax. lymphorrhea, bleeding.

The prognosis of occlusion of the subclavian artery depends on the nature and extent of the vessel lesion, as well as the timeliness of surgical intervention. Early surgery and good condition of the vessel wall is the key to restoring blood flow in the limb and vertebrobasilar basin in 96% of cases.

The subclavian artery is a paired organ that consists of the right and left arteries. It is part of the systemic circulation and begins in the anterior mediastinum. It is from this artery that the blood supply to the arms, neck and organs that are located in the upper body depends.

Structure

This artery originates in the anterior mediastinum, the right subclavian artery is the terminal branch of the brachiocephalic trunk, and the left one originates from the aortic arch. At the same time, the left subclavian artery is much longer than the right one, and its intrathoracic part is located behind the brachiocephalic vein. This artery goes around the top of the lung, and also the dome of the pleura, forming a convex arc. In the region of the first rib, the brachial plexus is located on it. Bypassing the rib, the artery goes under the collarbone and passes into the axillary artery.

There are three main divisions in the left and right subclavian arteries. The first section begins at the place of its formation and continues to the interstitial space. The second is located in the interstitial space, and the third section of the artery begins near the exit from the interstitial space and ends at the entrance to the axillary cavity.

Functions

Like any other, this artery is engaged in the delivery of blood to the organs. Numerous branches of the subclavian artery depart from its first section. One of them is the vertebral artery, which supplies the spinal cord, the hard shell of the brain, and muscles. From the lower surface of the subclavian artery, the internal thoracic artery originates, which supplies blood to the main bronchi, thyroid gland, sternum, diaphragm, tissue of the anterior and superior mediastinum, as well as the rectus abdominis and chest. The thyroid trunk departs from the inner edge of the scalene muscle and is divided into branches that supply blood to the larynx, muscles of the scapula and neck.

Only one branch departs from the second section of the artery - the costal-cervical trunk. It supplies blood to the spinal cord, spinal cord and other muscles. The transverse artery of the neck departs from the third section, which also supplies blood to the muscles of the shoulder and back.

Diseases

The main disease that can affect the branches of the subclavian artery and the artery itself is stenosis or narrowing of the lumen. The most common cause of stenosis is atherosclerotic changes in the vessels or thrombosis. Sometimes this disease is congenital, but more often acquired. Among the most common causes of subclavian artery stenosis are metabolic disorders in the body, inflammatory diseases and neoplasms. Severe stenosis, leading to a decrease in blood flow, causes a deficiency of oxygen and nutrients in the tissues. Also, stenosis can cause ischemic stroke. With stenosis, patients most often complain of pain from the affected limb. The pain is aggravated by physical activity.

Treatment Methods

There are several treatments for subclavian artery stenosis, the main ones being carotid-subclavian bypass and endovascular stenting. Carotid-subclavian bypass is usually recommended for patients with hypersthenic stature in whom it is difficult to isolate the first section of the artery. It is also recommended for stenosis in the second section.

X-ray endovascular stenting - treatment through a small incision in the skin 2-3 mm long through a puncture hole. It has great advantages over surgery, as it injures the patient less.

Left only subclavian artery, a. subclavia, refers to the number of branches extending directly from the aortic arch, while the right one is a branch of the truncus brachiocephalicus. The artery forms an arch convex upwards, enveloping the dome of the pleura. It leaves the chest cavity through the apertura superior, approaches the clavicle, lies down in the sulcus a. subclaviae I rib and bends over it. Here the subclavian artery can be pressed to stop bleeding to the 1st rib behind tuberculum m. scaleni. Further, the artery continues into the axillary fossa, where, starting from the outer edge of the 1st rib, it is called a. axillaris.

On its way, the subclavian artery passes along with the brachial plexus through the spatium interscalenum, therefore, 3 sections are distinguished in it: the first - from the place of origin to the entrance to the spatium interscalenum, the second - to the spatium interscalenum and the third - after leaving it, before moving to a . axillaris.

Branches of the first section of the subclavian artery (before entering the spatium interscalenum):

A. vertebralis, vertebral artery, the first branch extending upward in the interval between m. scalenus anterior and m. longus colli, goes to the foramen processus transversus of the VI cervical vertebra and rises up through the holes in the transverse processes of the cervical vertebrae to the membrana atlantooccipitalis posterior, perforating which it enters through the foramen magnum of the occipital bone into the cranial cavity. In the cranial cavity, the vertebral arteries of both sides converge to the midline and near the posterior edge of the bridge merge into one unpaired basilar artery, a. basilaris. On its way, it gives off small branches to the muscles, spinal cord and hard shell of the occipital lobes of the brain, as well as large branches:

a. spinalis anterior leaves in the cranial cavity near the confluence of two vertebral arteries and goes down and towards the midline towards the same-named artery of the opposite side, with which it merges into one trunk;
a. spinalis posterior departs from the vertebral artery immediately after its entry into the cranial cavity and also goes down the sides of the spinal cord. As a result, three arterial trunks descend along the spinal cord: unpaired - along the anterior surface (a. spinalis anterior) and two paired - along the posterolateral surface, one on each side (aa. spinales posteriores). All the way to the lower end of the spinal cord, they receive reinforcements in the form of g. spinales: in the neck - from aa. vertebrales, in the thoracic region - from aa. intercostales posteriores, in the lumbar - from aa. lumbales. Through these branches, anastomoses of the vertebral artery with the subclavian artery and the descending aorta are established;
A. Cerebelli inferior posterior is the largest of the a. vertebralis, begins near the bridge, goes back and, bypassing the medulla oblongata, branches on the lower surface of the cerebellum.

A. basilaris, basilar artery, obtained from the fusion of both vertebrates, unpaired, lies in the median groove of the bridge, at the front edge it is divided into two aa. cerebri posteribres (one on each side), which go back and up, go around the lateral surface of the legs of the brain and branch out on the lower, inner and outer surfaces of the occipital lobe. Taking into account the aa described above. communicantes posteriores from a. carotis interna, the posterior cerebral arteries are involved in the formation of the cerebral arterial circle, circulus arteriosus cerebri.

From trunk a. basilaris small branches depart to the bridge, to the inner ear, passing through the meatus acusticus internus, and two branches to the cerebellum: a. cerebelli inferior anterior and a. cerebelli superior. A. vertebralis, which runs parallel to the trunk of the common carotid artery and participates along with it in the blood supply to the brain, is a collateral vessel for the head and neck. Merged into one trunk, a. basilaris, two vertebral arteries and two aa merged into one trunk. spinales anteriores, form an arterial ring, which, along with circulus arteriosus cerebri, is important for the collateral circulation of the medulla oblongata.

Truncus thyrocervicalis, thyrocervical trunk, departs from a. subclavia up at the medial edge m. scalenus anterior, is about 4 cm long and divides into the following branches:

a. thyroidea inferior goes to the posterior surface of the thyroid gland, gives a. laryngea inferior, which branches in the muscles and mucous membrane of the larynx and anastomoses with a. laryngea superior; branches to the trachea, esophagus and thyroid gland; the latter anastomose with branches a. thyroidea superior from system a. carotis externa;
a. cervicalis ascendens ascends along m. scalenus anterior and supplies the deep muscles of the neck; c) a. suprascapularis goes down from the trunk and laterally, to the incusura scapulae, and, bending over the lig. transversum scapulae, branches in the dorsal muscles of the scapula; anastomoses with a. circumflexa scapulae.

A. thoracica interna, internal thoracic artery, departs from a. subclavia versus beginning a. vertebralis, goes down and medially, adjacent to the pleura; starting from the I costal cartilage, goes vertically down at a distance of about 12 mm from the edge of the sternum. Having reached the lower edge of the VII costal cartilage, a. thoracica interna is divided into two terminal branches: a. musculophrenica stretches laterally along the line of attachment of the diaphragm, giving branches to it and into the nearest intercostal spaces, and a. epigastrica superior - continues the path of a. thoracica interna downwards, penetrates into the sheath of the rectus abdominis muscle and, reaching the level of the navel, anastomoses with a. epigastica inferior (from a. iliaca externa). On its way a. thoracica interna gives branches to the nearest anatomical formations: the connective tissue of the anterior mediastinum, the thymus gland, the lower end of the trachea and bronchi, to the six upper intercostal spaces and the mammary gland. Its long branch, a. pericardiacophrenica, together with n. phrenicus goes to the diaphragm, giving branches to the pleura and pericardium along the way. Her rami intercostales anteribres run in the upper six intercostal spaces and anastomose with aa. intercostales posteriores (from the aorta). Branches of the second division of the subclavian artery:

Truncus costocervicalis, costocervical trunk, departs in the spatium interscalenum, goes back and up to the neck of the 1st rib, where it divides into two branches that penetrate the back muscles of the neck and give branches to the canalis vertebralis to the spinal cord and into the first and second intercostal spaces. Branches of the third division of the subclavian artery:

A. transversa colli, transverse artery of the neck, perforates the plexus brachialis, supplies neighboring muscles and descends along the medial edge of the scapula to its lower angle.