Each millimeter of the body's area is permeated with many capillary blood vessels, to which blood is delivered by arterioles and larger main vessels. And although the anatomy of the arteries is not difficult to understand, all the vessels of the body together form an integral branched transport system. Due to it, the tissues of the body are nourished and its vital activity is supported.
An artery is a blood vessel that resembles a tube in shape. It directs blood from the central circulatory organ (heart) to distant tissues. Most often, oxygenated arterial blood is delivered through these vessels. Oxygen-poor venous blood normally flows through only one artery - the pulmonary. But the general plan of the structure of the circulatory system is preserved, that is, in the center of the circles of blood circulation is the heart, from which arteries drain blood, and veins supply it.
Functionsarteries
Considering the anatomy of an artery, it is easy to assess its morphological qualities. This is a hollow elastic tube, the main function of which is to transport blood from the heart to the capillary bed. But this task is not the only one, since these vessels also perform other important functions. Among them:
- participation in the hemostasis system, counteracting intravascular thrombosis, closure of vascular damage by a clot;
- formation of a pulse wave and its transmission to vessels with a smaller caliber;
- supporting the level of blood pressure in the lumen of vessels at a great distance from the heart;
- venous pulse formation.
Hemostasis is a term that characterizes the presence of a coagulation and anticoagulation system inside each blood vessel. That is, after non-critical damage, the artery itself is able to restore blood flow and close the defect with a thrombus. The second component of the hemostasis system is the anticoagulant system. This is a complex of enzymes and receptor molecules that destroy a thrombus that forms without violating the integrity of the vascular wall.
If the clot formed spontaneously due to non-bleeding disorders, the arterial and venous hemostasis system will dissolve it on its own in the most efficient way available. However, this becomes impossible if the thrombus blocks the lumen of the artery, due to which thrombolytics of the anticoagulant system cannot reach its surface, as happens with a heart attack.myocardial or PE.
Artery pulse wave
The anatomy of veins and arteries is also different due to the difference in hydrostatic pressure in their lumen. In the arteries, the pressure is much higher than in the veins, which is why their wall contains more muscle cells, the collagen fibers of the outer shell are better developed in them. Blood pressure is generated by the heart at the time of left ventricular systole. Then a large portion of blood stretches the aorta, which, due to the elastic qualities, quickly shrinks back. This allows the left ventricle to receive blood first and then send it further when the aortic valve closes.
As you move away from the heart, the pulse wave will weaken, and it will not be enough to push the blood through only due to elastic stretching and compression. To maintain a constant level of blood pressure in the vascular arterial bed, muscle contraction will be required. To do this, there are muscle cells in the middle membrane of the arteries, which, after nervous sympathetic stimulation, will generate a contraction and push the blood to the capillaries.
The pulsation of the arteries also allows you to push blood through the veins, which are located in close proximity to the pulsating vessel. That is, arteries that come into contact with nearby veins cause them to pulsate and help return blood to the heart. A similar function is performed by skeletal muscles during their contraction. Such assistance is needed to push venous blood up against gravity.
Types of arterial vessels
The anatomy of an artery differs independing on its diameter and distance from the heart. More precisely, the general plan of the structure remains the same, but the severity of elastic fibers and muscle cells changes, as well as the development of the connective tissue of the outer layer. The artery consists of a multilayer wall and a cavity. The inner layer is the endothelium, located on the basement membrane and subendothelial connective tissue base. The latter is also called the internal elastic membrane.
Differences in types of arteries
The middle layer is the site of the greatest differences between types of arteries. It contains elastic fibers and muscle cells. On top of it is an external elastic membrane, completely covered from above with loose connective tissue, which makes it possible for the smallest arteries and nerves to penetrate into the middle shell. And depending on the caliber, as well as the structure of the middle shell, there are 4 types of arteries: elastic, transitional and muscular, as well as arterioles.
Arterioles are the smallest arteries with the thinnest connective tissue sheath and absent elastic fibers in the middle sheath. These are one of the most common arterial vessels directly adjacent to the capillary bed. In these areas, the main blood supply is replaced by regional and capillary. It occurs in the interstitial fluid directly near the group of cells to which the vessel has approached.
Main arteries
Main vessels are such human arteries, the anatomy of which is of great importance for surgery. Toit includes large vessels of elastic and transitional type: aorta, iliac, renal arteries, subclavian and carotid. They are called trunk for the reason that they deliver blood not to organs, but to areas of the body. For example, the aorta, as the largest vessel, carries blood to all parts of the body.
The carotid arteries, the anatomy of which will be discussed below, deliver nutrients and oxygen to the head and brain. Also, the main vessels include the femoral, brachial arteries, celiac trunk, mesenteric vessels and many others. This concept does not so much define the context for studying the anatomy of the arteries, but is intended to clarify the regions of blood supply. This allows us to understand that blood is delivered from the heart through large to small arteries and in a huge area where the main vessels are represented, neither gas exchange nor exchange of metabolites is possible. They perform only a transport function and are involved in hemostasis.
Arteries of the neck and head
Arteries of the head and neck, the anatomy of which allows us to understand the nature of vascular lesions of the brain, originate from the aortic arch and subclavian vessels. The most significant is the pool of carotid arteries (right and left), through which the largest amount of oxygenated blood enters the head tissue.
The right common carotid (carotid) artery branches off from the brachiocephalic trunk, which originates on the aortic arch. To the left is a branch of the left common carotid and left subclavian artery.
Blood supply to the brain
Both carotid arteries are divided into two large branches - the external and internal carotid artery. The anatomy of these vessels is notable for multiple anastomoses between the branches of these pools in the region of the facial skull.
The external carotid arteries are responsible for the blood supply to the muscles and skin of the face, tongue, larynx, and the internal carotid arteries are responsible for the brain. Inside the skull there is an additional source of blood supply - a pool of vertebral arteries (anatomy thus provided a backup source of blood supply). They originate from the subclavian vessels, after which they go up and enter the cranial cavity.
Further, they merge and form an anastomosis between the arteries of the internal carotid artery, creating the Willisian circle of blood circulation in the brain. After the vertebral and internal carotid basins of the carotid arteries are combined with each other, the anatomy of the blood supply to the brain becomes more complicated. This is a backup mechanism that protects the main organ of the nervous system from most ischemic episodes.
Arteries of the upper limbs
The upper limb belt is fed by a group of arteries that originate from the aorta. To the right of it, the brachiocephalic trunk branches off, giving rise to the right subclavian artery. The anatomy of the blood supply to the left limb is slightly different: the subclavian artery on the left is separated directly from the aorta, and not from the common trunk with the carotid arteries. Because of this feature, a special sign can be observed: with significant hypertrophy of the left atrium or severe stretching, it presses the subclavian artery, due to which itpulsation weakens.
From the subclavian arteries, after departing from the aorta or the right brachiocephalic trunk, a group of vessels later branches off, going to the free upper limb and shoulder joint.
On the arm, the largest arteries are the brachial and ulnar, for a long time going along with the nerves and veins in one channel. True, this description is very inaccurate, and the location is variable for each individual. Therefore, the course of the vessels should be studied on a macropreparation, according to diagrams or anatomical atlases.
Abdominal arterial bed
In the abdominal cavity, the blood supply is also of the main type. The celiac trunk and several mesenteric arteries branch off from the aorta. From the celiac trunk, branches are sent to the stomach and pancreas, liver. To the spleen, the artery sometimes branches off from the left gastric, and sometimes from the right gastroduodenal. These features of the blood supply are individual and variable.
In the retroperitoneal space there are two kidneys, each of which is directed by two short renal vessels. The left renal artery is much shorter and less commonly affected by atherosclerosis. Both of these vessels are capable of withstanding great pressure, and a quarter of each systolic ejection of the left ventricle flows through them. This proves the fundamental importance of the kidneys as organs of blood pressure regulation.
Pelvic arteries
The aorta enters the pelvic cavity, which is divided into two large branches - the common iliac arteries. The right ones depart from themand the left external and internal iliac vessels, each of which is responsible for the blood circulation of its parts of the body. The external iliac artery gives a number of small branches and goes to the lower limb. From now on, its continuation will be called the femoral artery.
The internal iliac arteries give many branches to the genitals and bladder, the muscles of the perineum and rectum, and to the sacrum.
Arteries of the lower limbs
In the arteries of the lower extremities, the anatomy is simpler than that of the vessels of the small pelvis, due to the more pronounced trunk blood supply. In particular, the femoral artery, branching off from the external iliac, descends and gives off many branches for the blood supply to the muscles, bones and skin of the lower extremities.
On its way, it gives off a large descending branch, popliteal, anterior and posterior tibial, peroneal branches. On the foot, branches from the tibial and peroneal arteries to the ankles and ankle joints, calcaneal bones, foot muscles and fingers.
Circulation pattern of the lower extremities is symmetrical - the vessels are the same on both sides.
