Each millimeter of the bodyโs body area is penetrated by a multitude of capillary blood vessels, to which blood is delivered by arterioles and larger main vessels. And although the anatomy of the arteries is simple to understand, all the vessels of the body together make up a single, branched transport system. Due to it, the body's tissues are nourished and its vital activity is supported.
An artery is a blood vessel in the shape of a tube. It directs blood from the central circulatory organ (heart) to distant tissues. Most often, oxygenated arterial blood is delivered through these vessels. Poor oxygen 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 the arteries divert blood, and the veins supply it.
Arterial function
Considering the anatomy of an artery, it is easy to evaluate its morphological qualities. This is a hollow elastic tube, the main function of which is the transportation of 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 hemostatic system, counteraction to intravascular thrombosis, closure of vascular damage by a thrombus;
- pulse wave formation and its transmission to vessels with a smaller caliber;
- maintaining blood pressure in the lumen of blood vessels at a great distance from the heart;
- formation of a venous pulse.
Hemostasis is a term that describes the presence of a coagulation and anticoagulation mechanism within each blood vessel. That is, after non-critical damage, the artery itself is able to restore blood flow and close the defect with a blood clot. The second component of the hemostatic system is the anticoagulant system. This is a complex of enzymes and receptor molecules that destroy a blood clot that forms without violating the integrity of the vascular wall.
If a blood clot formed independently due to disorders not related to bleeding, the hemostatic system of arteries and veins will dissolve it on its own in the most effective way available. However, this becomes impossible if the thrombus blocks the lumen of the artery, because of which thrombolytics of the anticoagulant system cannot get to its surface, as happens with myocardial infarction or pulmonary embolism.
Pulse Wave Artery
The anatomy of the veins and arteries is also different due to the difference in hydrostatic pressure in their lumen. In arteries, the pressure is much higher than in the veins, because of which their wall contains more muscle cells, collagen fibers of the outer membrane are better developed in them. Blood pressure is generated by the heart at the time of systole of the left ventricle. Then a large portion of blood stretches the aorta, which, due to its elastic qualities, quickly compresses back. This allows you to first take a portion of blood from the left ventricle, and then direct 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 blood through elastic stretching and contraction. To maintain a constant level of blood pressure in the vascular arterial bed, muscle contraction is required. To do this, in the middle membrane of the arteries there are muscle cells that, after nervous sympathetic stimulation, will generate a contraction and the blood will be pushed to the capillaries.
Arterial pulsation also allows blood to be pushed through veins that are located in close proximity to a pulsating vessel. That is, arteries that come in contact with the adjacent veins give rise to their pulsation and help return blood to the heart. The skeletal muscles perform a similar function during their contraction. Such help is needed to push venous blood up against gravity.
Types of arterial vessels
The artery anatomy differs depending 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, as well as the development of connective tissue of the outer layer, change. The artery consists of a multilayer wall and cavity. The inner layer is the endothelium located on the basement membrane and subendothelial connective tissue base. The latter is also called an internal elastic membrane.
Differences in Arterial Types
The middle layer is the site of the greatest differences between the types of arteries. It contains elastic fibers and muscle cells. On top of it is an outer elastic membrane, completely covered with loose connective tissue on top, allowing the smallest arteries and nerves to penetrate into the middle membrane. And depending on the caliber, as well as the structure of the middle shell, 4 types of arteries are distinguished: elastic, transitional and muscular, as well as arterioles.
Arterioles are the smallest arteries with the thinnest connective tissue membrane and absent elastic fibers in the middle membrane. These are one of the most common arterial vessels that are directly adjacent to the capillary bed. In these areas, the main blood supply is replaced by regional and capillary. It flows in the interstitial fluid directly at the group of cells to which the vessel approached.
Trunk arteries
The main vessels are such human arteries, the anatomy of which is essential for surgery. These include large vessels of the elastic and transitional type: aorta, iliac, renal arteries, subclavian and carotid. Trunk they are called 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 to the main vessels include the femoral, brachial arteries, celiac trunk, mesenteric vessels and many others. This concept not only determines the context of the study of arterial anatomy, but also aims to clarify the regions of blood supply. This makes it possible to understand that blood is delivered from the heart through large to small arteries and in the vast area where the main vessels are represented, neither gas exchange nor metabolite exchange 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, originates from the aortic arch and subclavian vessels. The most significant is the pool of carotid arteries (right and left), through which the greatest 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 arteries. The anatomy of these vessels is notable for multiple anastomoses between the branches of these pools in the area of โโthe 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 ones - of the brain. Inside the skull there is an additional source of blood supply - the pool of vertebral arteries (the anatomy thus provided for a backup source of blood supply). They originate from the subclavian vessels, after which they go up and enter the cranial cavity.
Then they merge and form an anastomosis between the arteries of the basin of the internal carotid artery, creating the Wilizian circle of blood circulation of the brain. After the vertebral and internal carotid pools of the carotid arteries are joined together, 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 extremities
The belt of the upper extremities feeds a group of arteries that originate from the aorta. The brachiocephalic trunk branches to the right of it, 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 trunk that is common with the carotid arteries. Because of this feature, a special symptom can be observed: with significant hypertrophy of the left atrium or severe distension, it suppresses the subclavian artery, due to which its pulsation weakens.
From the subclavian arteries, after departing from the aorta or the right brachiocephalic trunk, a group of vessels branching to the free upper limb and shoulder joint later branches.
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 blood vessels should be studied on a macrodrug, according to diagrams or anatomical atlases.
Arterial bed of the abdominal cavity
In the abdominal cavity, the blood supply is also of the main type. The celiac trunk and several mesenteric arteries branch 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 blood supply are individual and variable.
Two kidneys are located in the posteriorperitoneal space, each of which is sent two short renal vessels. The left renal artery is much shorter and less likely to be affected by atherosclerosis. Both of these vessels can withstand a lot of 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 for regulating blood pressure.
Pelvic arteries
The aorta enters the pelvic cavity, which is divided into two large branches - the common iliac arteries. Right and left external and internal iliac vessels depart from them, each of which is responsible for the blood circulation of its body parts. 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, as well as to the sacrum.
Arteries of the lower extremities
In the arteries of the lower extremities, the anatomy is simpler than in the vessels of the small pelvis, due to the more pronounced magistracy of blood supply. In particular, the femoral artery, branching from the external iliac, descends and gives up many branches for blood supply to the muscles, bones and skin of the lower extremities.
On its way, it gives up a large descending branch, the popliteal, anterior and posterior tibial, peroneal branch. On the foot, branches already extend from the tibial and peroneal arteries to the ankles and ankle joints, calcaneus, muscles of the foot and fingers.
The circulatory system of the lower extremities is symmetrical - the vessels are the same on both sides.