Artery message. The largest artery in the human body. According to the structure of the wall

The largest artery is. Arteries depart from it, which, as they move away from the heart, branch and become smaller. The thinnest arteries are called arterioles. In the thickness of the organs, the arteries branch up to the capillaries (see). Nearby arteries are often connected, through which collateral blood flow occurs. Usually, arterial plexuses and networks are formed from the anastomosing arteries. An artery that supplies blood to a part of an organ (a segment of the lung, liver) is called segmental.

The wall of the artery consists of three layers: internal - endothelial, or intima, middle - muscular, or media, with a certain amount of collagen and elastic fibers, and external - connective tissue, or adventitia; the wall of the artery is richly supplied with vessels and nerves, located mainly in the outer and middle layers. Based on the structural features of the wall, the arteries are divided into three types: muscular, muscular - elastic (for example, carotid arteries) and elastic (for example, the aorta). Muscular-type arteries include small arteries and arteries of medium caliber (for example, radial, brachial, femoral). The elastic frame of the artery wall prevents its collapse, ensuring the continuity of blood flow in it.

Usually, the arteries lie for a long distance in depth between the muscles and near the bones, to which the artery can be pressed during bleeding. On a superficially lying artery (for example, the radial one), it is palpated.

The walls of the arteries have their own supplying blood vessels (“vessels of the vessels”). The motor and sensory innervation of the arteries is carried out by sympathetic, parasympathetic nerves and branches of the cranial or spinal nerves. The nerves of the artery penetrate into the middle layer (vasomotors - vasomotor nerves) and contract the muscle fibers of the vascular wall and change the lumen of the artery.

Rice. 1. Arteries of the head, trunk and upper limbs:
1-a. facialis; 2-a. lingualis; 3-a. thyreoidea sup.; 4-a. carotis communis sin.; 5-a. subclavia sin.; 6-a. axillaris; 7 - arcus aortae; £ - aorta ascendens; 9-a. brachialis sin.; 10-a. thoracica int.; 11 - aorta thoracica; 12 - aorta abdominalis; 13-a. phrenica sin.; 14 - truncus coeliacus; 15-a. mesenterica sup.; 16-a. renalis sin.; 17-a. testicular sin.; 18-a. mesenterica inf.; 19-a. ulnaris; 20-a. interossea communis; 21-a. radialis; 22-a. interossea ant.; 23-a. epigastric inf.; 24 - arcus palmaris superficialis; 25 - arcus palmaris profundus; 26 - a.a. digitales palmares communes; 27 - a.a. digitales palmares propriae; 28 - a.a. digitales dorsales; 29 - a.a. metacarpeae dorsales; 30 - ramus carpeus dorsalis; 31-a, profunda femoris; 32-a. femoralis; 33-a. interossea post.; 34-a. iliaca externa dextra; 35-a. iliaca interna dextra; 36-a. sacraiis mediana; 37-a. iliaca communis dextra; 38 - a.a. lumbales; 39-a. renalis dextra; 40 - a.a. intercostales post.; 41-a. profunda brachii; 42-a. brachialis dextra; 43 - truncus brachio-cephalicus; 44-a. subciavia dextra; 45-a. carotis communis dextra; 46-a. carotis externa; 47-a. carotis interna; 48-a. vertebralis; 49-a. occipitalis; 50 - a. temporalis superficialis.

Rice. 2. Arteries of the anterior surface of the lower leg and rear of the foot:
1 - a, genu descendens (ramus articularis); 2-ram! musculares; 3-a. dorsalis pedis; 4-a. arcuata; 5 - ramus plantaris profundus; 5-a.a. digitales dorsales; 7-a.a. metatarseae dorsales; 8 - ramus perforans a. peroneae; 9-a. tibialis ant.; 10-a. recurrens tibialis ant.; 11 - rete patellae et rete articulare genu; 12-a. Genu sup. lateralis.

Rice. 3. Arteries of the popliteal fossa and posterior surface of the lower leg:
1-a. poplitea; 2-a. Genu sup. lateralis; 3-a. Genu inf. lateralis; 4-a. peronea (fibularis); 5 - rami malleolares tat.; 6 - rami calcanei (lat.); 7 - rami calcanei (med.); 8 - rami malleolares mediales; 9-a. tibialis post.; 10-a. Genu inf. medialis; 11-a. Genu sup. medialis.

Rice. 4. Arteries of the plantar surface of the foot:
1-a. tibialis post.; 2 - rete calcaneum; 3-a. plantaris lat.; 4-a. digitalis plantaris (V); 5 - arcus plantaris; 6 - a.a. metatarsea plantares; 7-a.a. digitales propriae; 8-a. digitalis plantaris (hallucis); 9-a. plantaris medialis.

Rice. 5. Arteries of the abdominal cavity:
1-a. phrenica sin.; 2-a. gastric sin.; 3 - truncus coeliacus; 4-a. lienalis; 5-a. mesenterica sup.; 6-a. hepatica communis; 7-a. gastroepiploica sin.; 8 - a.a. jejunales; 9-a.a. ilei; 10-a. colica sin.; 11-a. mesenterica inf.; 12-a. iliaca communis sin.; 13 -aa, sigmoideae; 14-a. rectalis sup.; 15-a. appendicis vermiformis; 16-a. ileocolica; 17-a. iliaca communis dextra; 18-a. colica. dext.; 19-a. pancreaticoduodenal inf.; 20 a. colica media; 21-a. gastroepiploica dextra; 22-a. gastroduodenalis; 23-a. gastrica dextra; 24-a. hepatica propria; 25 - a, cystica; 26 - aorta abdominalis.

Arteries (Greek arteria) - a system of blood vessels extending from the heart to all parts of the body and containing blood enriched with oxygen (an exception is a. pulmonalis, which carries venous blood from the heart to the lungs). The arterial system includes the aorta and all its branches down to the smallest arterioles (Fig. 1-5). Arteries are usually designated by a topographic feature (a. facialis, a. poplitea) or by the name of the supplied organ (a. renalis, aa. cerebri). Arteries are cylindrical elastic tubes of various diameters and are divided into large, medium and small. The division of arteries into smaller branches occurs according to three main types (V. N. Shevkunenko).

With the main type of division, the main trunk is well defined, gradually decreasing in diameter as the secondary branches depart from it. The loose type is characterized by a short main trunk, quickly disintegrating into a mass of secondary branches. Transitional, or mixed, type occupies an intermediate position. Branches of arteries are often connected to each other, forming anastomoses. There are intrasystemic anastomoses (between branches of one artery) and intersystemic (between branches of different arteries) (B. A. Dolgo-Saburov). Most anastomoses exist permanently as roundabout (collateral) circulatory pathways. In some cases, collaterals may reappear. Small arteries with the help of arteriovenous anastomoses (see) can directly connect to veins.

Arteries are derivatives of the mesenchyme. In the process of embryonic development, muscle, elastic elements and adventitia, also of mesenchymal origin, join the initial thin endothelial tubules. Histologically, three main membranes are distinguished in the wall of the artery: internal (tunica intima, s. interna), middle (tunica media, s. muscularis) and external (tunica adventitia, s. externa) (Fig. 1). According to the structural features, the arteries of the muscular, muscular-elastic and elastic types are distinguished.

Muscular-type arteries include small and medium-sized arteries, as well as most of the arteries of the internal organs. The inner lining of the artery includes the endothelium, subendothelial layers, and the inner elastic membrane. The endothelium lines the lumen of the artery and consists of flat cells elongated along the axis of the vessel with an oval nucleus. The boundaries between cells have the appearance of a wavy or finely serrated line. According to electron microscopy, a very narrow (about 100 A) gap is constantly maintained between cells. Endothelial cells are characterized by the presence in the cytoplasm of a significant number of bubble-like structures. The subendothelial layer consists of connective tissue with very thin elastic and collagen fibers and poorly differentiated stellate cells. The subendothelial layer is well developed in the arteries of large and medium caliber. The internal elastic, or fenestrated, membrane (membrana elastica interna, s.membrana fenestrata) has a lamellar-fibrillar structure with holes of various shapes and sizes and is closely connected with the elastic fibers of the subendothelial layer.

The middle shell consists mainly of smooth muscle cells, which are arranged in a spiral. Between muscle cells there is a small amount of elastic and collagen fibers. In medium-sized arteries, at the border between the middle and outer shells, elastic fibers can thicken, forming an outer elastic membrane (membrana elastica externa). The complex musculo-elastic skeleton of muscular-type arteries not only protects the vascular wall from overstretching and rupture and ensures its elastic properties, but also allows the arteries to actively change their lumen.

Arteries of the muscular-elastic, or mixed, type (for example, the carotid and subclavian arteries) have thicker walls with an increased content of elastic elements. Fenestrated elastic membranes appear in the middle shell. The thickness of the internal elastic membrane also increases. An additional inner layer appears in the adventitia, containing separate bundles of smooth muscle cells.

The vessels of the largest caliber belong to the elastic type arteries - the aorta (see) and the pulmonary artery (see). In them, the thickness of the vascular wall increases even more, especially the middle membrane, where elastic elements predominate in the form of 40-50 powerfully developed fenestrated elastic membranes connected by elastic fibers (Fig. 2). The thickness of the subendothelial layer also increases, and in addition to loose connective tissue rich in stellate cells (Langhans layer), separate smooth muscle cells appear in it. The structural features of the elastic type arteries correspond to their main functional purpose - mainly passive resistance to a strong push of blood ejected from the heart under high pressure. Different sections of the aorta, differing in their functional load, contain a different amount of elastic fibers. The wall of the arteriole retains a strongly reduced three-layer structure. Arteries that supply blood to internal organs have structural features and intraorgan distribution of branches. Branches of the arteries of hollow organs (stomach, intestines) form networks in the wall of the organ. Arteries in parenchymal organs have a characteristic topography and a number of other features.

Histochemically, a significant amount of mucopolysaccharides is found in the ground substance of all the membranes of the arteries, and especially in the inner membrane. The walls of the arteries have their own blood vessels supplying them (a. and v. vasorum, s. vasa vasorum). Vasa vasorum are located in adventitia. The nutrition of the inner shell and the part of the middle shell bordering it is carried out from the blood plasma through the endothelium by pinocytosis. Using electron microscopy, it was found that numerous processes extending from the basal surface of endothelial cells reach muscle cells through holes in the inner elastic membrane. When the artery contracts, many small and medium-sized windows in the internal elastic membrane partially or completely close, which makes it difficult for nutrients to flow through the processes of endothelial cells to muscle cells. Great importance in the nutrition of areas of the vascular wall, devoid of vasa vasorum, is attached to the main substance.

The motor and sensory innervation of the arteries is carried out by sympathetic, parasympathetic nerves and branches of the cranial or spinal nerves. The nerves of the arteries, which form plexuses in the adventitia, penetrate into the middle shell and are designated as vasomotor nerves (vasomotors), which contract the muscle fibers of the vascular wall and narrow the lumen of the artery. The walls of the artery are equipped with numerous sensitive nerve endings - angioreceptors. In some parts of the vascular system, there are especially many of them and they form reflexogenic zones, for example, at the place of division of the common carotid artery in the area of ​​the carotid sinus. The thickness of the walls of the artery and their structure are subject to significant individual and age-related changes. And arteries have a high ability to regenerate.

Pathology of the arteries - see Aneurysm, Aortitis, Arteritis, Atherosclerosis, Coronaritis., Coronarosclerosis, Endarteritis.

See also Blood vessels.

Carotid artery

Rice. 1. Arcus aortae and its branches: 1 - mm. stylohyoldeus, sternohyoideus and omohyoideus; 2 and 22 - a. carotis int.; 3 and 23 - a. carotis ext.; 4 - m. cricothyreoldeus; 5 and 24 - aa. thyreoideae superiores sin. et dext.; 6 - glandula thyreoidea; 7 - truncus thyreocervicalis; 8 - trachea; 9-a. thyreoidea ima; 10 and 18 - a. subclavia sin. et dext.; 11 and 21 - a. carotis communis sin. et dext.; 12 - truncus pulmonais; 13 - auricula dext.; 14 - pulmo dext.; 15 - arcus aortae; 16-v. cava sup.; 17 - truncus brachiocephalicus; 19 - m. scalenus ant.; 20 - plexus brachialis; 25 - glandula submandibularis.

Rice. 2. Arteria carotis communis dextra and its branches; 1-a. facialis; 2-a. occipitalis; 3-a. lingualis; 4-a. thyreoidea sup.; 5-a. thyreoidea inf.; 6-a. carotis communis; 7 - truncus thyreocervicalis; 8 and 10 - a. subclavia; 9-a. thoracica int.; 11 - plexus brachialis; 12-a. transversa colli; 13-a. cervicalis superficialis; 14-a. cervicalis ascendens; 15-a. carotis ext.; 16-a. carotis int.; 17-a. vagus; 18 - n. hypoglossus; 19-a. auricularis post.; 20-a. temporalis superficialis; 21-a. zygomaticoorbitalis.

Rice. 1. Cross section of the artery: 1 - outer shell with longitudinal bundles of muscle fibers 2, 3 - middle shell; 4 - endothelium; 5 - internal elastic membrane.

Rice. 2. Cross section of the thoracic aorta. The elastic membranes of the middle shell are shortened (o) and relaxed (b). 1 - endothelium; 2 - intima; 3 - internal elastic membrane; 4 - elastic membranes of the middle shell.

ARTERIES(Greek arteria, singular) - blood vessels that carry blood enriched in the lungs with oxygen from the heart to all parts and organs of the body. The exception is the pulmonary trunk (see), which carries venous blood from the heart to the lungs.

Rice. 2. Arteries of the anterior surface of the lower leg and rear of the foot: 1 - a. genus descendens (ramus articularis); 2 - rami musculares; 3-a. dorsalis pedis; 4-a. arcuata; 5 - ramus plantaris profundus; 6 - a.a. digitales dorsales; 7 - a.a. metatarseae dorsales; 8-r. perforans a. peroneae; 9-a. tibialis ant.; 10-a. recurrens tibialis ant.; 11 - rete patellae et rete articulare genus; 12-a. genus superior lat.

Rice. 3. Arteries of the popliteal fossa and the posterior surface of the lower leg: 1 - a. poplitea; 2-a. genus superior lat.; 3-a. genus inferior lat.; 4-a. peronea (fibularis); 5-rr. malleolares lat.; 6-rr. calcanei (lat.); 7-rr. calcanei (med.); 8-rr. malleolares med.; 9-a. tibialis post.; 10-a. genus inferior med.; 11 - a. genus superior med.

In ancient times, the idea was created that air or air and blood circulate in the artery, since during the autopsy of corpses, the arteries turned out to be empty in most cases. The ancient Greeks also referred to the term "artery" as the windpipe - the trachea.

The totality of arteries: from the largest trunk - the aorta (see), originating from the left ventricle of the heart, to the smallest branches in the organs - precapillary arterioles - makes up the arterial system (printing. Fig. 2-6), which is part of the cardiovascular system ( cm.).

Arteries or their branches are named according to various criteria: topographic (for example, a. subclavia, a. poplitea), by the name of the organ they supply with blood (for example, a. renalis, a. uterina, a. testicularis), or part body (eg, a. dorsalis pedis, a. femoralis). A number of arteries have several names (synonyms) that appeared as a result of the revision of anatomical nomenclatures. Some large arteries are called the trunk (truncus), small arterial vessels are called branches (rami), the smallest arteries are called arterioles (arteriola), arterioles that pass into capillaries (see) are called precapillary arterioles (arteriola precapillaris), or metarterioles (metarteriola) .

Rice. 6. Arteries of the head, trunk and upper limbs: 1 - a. facialis; 2-a. lingualis; 3 - a. thyreoidea sup.; 4 - a. carotis communis sin.; 5-a. subclavia sin.; 6-a. axillaris; 7-arcus aortae; aorta ascendens; 9-a. brachialis sin.; 10-a. thoracica int.; 11-aorta thoracica; / 2- aorta abdominalis; 13-a. phrenica inf. sin.; 14 - truncus celiacus; 15-a. mesenterica sup.; 16-a. renalis sin.; 17-a. testicularis sin.; 18-a. mesenterica inf.; 19-a. ulnaris; 20-a. interossea communis; 21-a. radialis; 22-a. interossea ant.; 23-a. epigastric inf.; 24-arcus palmaris superficialis; 25-arcus palmaris profundus; 26 - a.a. digitales palmares communes; 27-a.a. digitales palmares propriae; 28-a.a. digitales dorsales; 29 - a.a. metacarpeae dorsales; 30 - ramus carpeus dorsalis; 31-a. profunda femoris; 32-a. femoralis; 33-a. interossea post.; 34-a. iliaca externa dext.; 35-a. iliaca int. dext.; 36-a. sacralis mediana; 37-a. iliaca communis dext.; 38 - a.a. lumbales; 39-a. renalis dext.; 40 - a.a. intercostales post.; 41-a. profunda brachii; 42-a. brachialis dext.; 43 - truncus brachiocephalicus; 44-a. subclavia dext.; 45-a. carotis communis dext.; 46-a. carotis ext.; 47-a. carotis int.; 48-a. vertebralis; 49-a. occipitalis; 50-a. temporalis superficialis.

Rice. 1. Development of human arteries. A - E - development of the celiac trunk, superior and inferior mesenteric arteries in the embryo: A - 4th week; B - 5th week, C - 6th week; G - 7th week; D - arteries of the body wall in the embryo of the 7th week 1 - pharynx; 2 - pulmonary kidney; 3 - liver; 4-a. omphalomesenterica; 5 - a. umbilicalis; 6 - hindgut; 7 - allantois; 8 - yolk sac; 9 - stomach; 10 - ventral segmental artery; and - a. vertebralis; 12 - a. subclavia; 13 - truncus celiacus; 14 - pancreas; 15-a. mesenterica inf.; 16-a. basilaris; 17 - large intestine; 18-a. sacralis mediana; 19-a. mesenterica sup.; 20 - a. carotis ext.; 21-a. intercostalis suprema; 22 - aorta; 23-a. intercostalis post.; 24-a. lumbalis; 25-a. epigastric inf.; 26-a. ischiadica; 27-a. iliaca ext.; 28-a. thoracica int.; 29-a. carotis int.

Embryology

Rice. 4. Arteries of the plantar surface of the foot: 1 - a. tibialis post.; 2 - rete calcaneum; 3-a. plantaris lat.; 4-a. digitalis plantaris (V); 5 - arcus plantaris; 6 - a.a. metatarsea plantares; 7 - a.a. digitales propriae; 8-a. digitalis plantaris (hallucis); 9-a. plantaris medialis.

Rice. 5. Arteries of the abdominal cavity: 1 - a. phrenica inferior sin.; 2-a. gastric sin.; 3 - truncus celiacus; 4-a. lienalis; 5-a. mesenterica sup.; 6-a. hepatica communis; 7-a. gastroepiploica sin.; 8 - a.a. jejunales; 9 - a.a. ilei; 10-a. colica sin.; 11-a. mesenterica inf.; 12 a. iliaca communis sin.; 13 - sigmoideae; 14_a. rectalis sup.; 15-a. appendicularis; 16-a. ileocolica; 17-a. iliaca communis dext.; 18-a. colica dext.; 19-a. pancreaticoduodenalis inf.; 20-n. colica media; 21-a. gastroepiploica dext.; 22-a. gastroduodenalis; 23-a. gastrica dext.; 24-a. hepatica propria; 25-a. cystica; 26 - aorta abdominalis.

Arteries develop from mesenchyme. In vertebrate and human embryos, the arterial trunk departs from the heart, which, heading to the head section of the embryo, soon divides into two ventral aorta. The latter are connected by six arterial gill arches to the dorsal aortas (see Aorta, comparative anatomy). A number of paired arterial vessels depart from the dorsal aortas, running along the sides of the neural tube in the dorsal direction between the somites (dorsal intersegmental arteries). In addition to them, two other types of paired arteries depart from the aorta of the embryo: lateral segmental arteries and ventral segmental arteries. The ascending aorta (aorta ascendens) and the pulmonary trunk (truncus pulmonalis) develop from the arterial trunk; the initial sections of the ventral and dorsal aortas, connected by 6 arterial gill arches, give rise to the internal, external and common carotid arteries (aa. carotis interna, externa et communis), to the right of the brachiocephalic trunk and subclavian artery (trartery uncus brachiocephalicus and a. subclavia dext .), on the left - the aortic arch (arcus aortae), pulmonary arteries (aa. pulmonales) and arterial duct (ductus arteriosus). From the dorsal intersegmental arteries, the vertebral arteries (aa. vertebrales) are formed, more cranially - the basilar artery (a. basilaris) and its branches. Caudal to the level of origin of the vertebral arteries from the dorsal intersegmental arteries are formed intercostal and lumbar arteries (aa. intercostales post, et aa. lumbales). Numerous anastomoses of these vessels form the internal thoracic artery (a. thoracica int.) and the superior and inferior epigastric arteries (aa. epigastricae sup. et inf). The lateral segmental arteries are associated with the developing urinary-genital organs. In embryos in the early stages of development, the branches of the lateral segmental arteries form the glomeruli of the tubules of the primary kidney (mesonephros). From the lateral segmental arteries, the renal, adrenal and gonadal arteries develop (aa. renales, aa. suprarenales et aa. testiculares, s. ovaricae). The ventral segmental arteries are connected to the yolk sac and the intestinal tract. In embryos of the early stages of development, they are directed laterally along the dorsal wall of the primary intestine, and from here into the walls of the yolk sac, constituting the arterial part of the yolk circulation of the embryo. Later, when the intestine separates from the yolk sac and the mesentery appears, the paired ventral segmental arteries unite and form the arteries located in the mesentery (tsvetn. rice. 1): celiac trunk (truncus celiacus), superior and inferior mesenteric arteries (aa. mesentericae sup. et inf.). In the caudal region, umbilical arteries (aa. umbilicales) develop from the ventral segmental arteries. In the process of development of the upper limbs, the axial artery grows into them as a continuation of the subclavian artery, the remnant of which later in the region of the forearm is the interosseous artery (a. interossea communis). The vessels of the developing hand are connected with the axial artery. In the later stages of development, the connection with this artery disappears and the median artery develops in parallel with it. The radial and ulnar arteries (aa. radialis et ulnaris) develop as branches of the axial artery. The primary artery of the leg, like the arm, is axial, departs from the initial section of the umbilical artery and is called the sciatic artery. In the later stages of development, it loses its significance, and only the peroneal artery (a. peronea) and a number of small arteries of the lower limb remain from it, and the external iliac artery (a. iliaca externa) receives significant development, and its continuation is the femoral, popliteal and the posterior tibial artery (a. femoralis, a. poplitea et tibialis post.) make up the main arterial line of the leg. After birth, with the cessation of placental circulation, the proximal parts of the umbilical arteries form the internal iliac arteries (aa. iliacae int.), and the umbilical artery itself is reduced and becomes the medial umbilical ligament (lig. umbilicale mediale).

Anatomy and histology

Arteries are cylindrical tubes with a very complex wall structure. In the course of successive branching of the arteries, the diameter of their lumen gradually decreases, while the total diameter of the arterial bed increases significantly. There are large, medium and small arteries.

Rice. 1. Cross section of an artery and its accompanying vein: A - artery; B - vein. 1 - tunica intima; 2 - tunica media; 3 - tunica externa; 4 - membrana elastica int.; 5 - membrana elastica ext.; 6 - vasa vasorum.

There are three membranes in the wall of the arteries: internal (tunica intima), middle (tunica media) and external (tunica externa, s. tunica adventitia) (Fig. 1). The walls of large arteries are dominated by intercellular substance in the form of elastic fibers and membranes. Such arteries are vessels of the elastic type of structure (arteria elastotypica). The walls of arteries of small and partly medium caliber are dominated by smooth muscle tissue with a small amount of intercellular substance. Such arteries are classified as muscular type of structure (arteria myotypica). Part of the arteries of medium caliber has a mixed type of structure (arteria mixtotypica).

Inner shell - tunica intima- inner cell layer - formed by the endothelium (endothelium) and the underlying subendothelial layer (stratum subendotheliale). The aorta has the thickest cell layer. As the arteries branch, it gradually becomes thinner and passes into the capillaries. Endothelial cells look like thin plates arranged in one row. This structure is due to the modeling role of blood flow. In the subendothelial layer, the cells have processes with which they contact each other, forming a syncytium. In addition to the trophic function, the inner cell layer also has regenerative properties, showing great potential for development. At the site of damage to the artery wall, it is a source of development of various types of connective tissue, including smooth muscles. In arterial homotransplantation, this vessel structure serves as a source of tissue that fouls the graft.

Middle shell - tunica media It is predominantly made up of smooth muscle tissue. In the course of cell development, intermediate, or intercellular, structures are formed in the form of a network of elastic fibers, elastic membranes, argyrophilic fibrils, and the main intermediate substance that make up the elastic stroma as a whole.

Rice. 2. Elastic stroma of the artery wall of the muscular type with complete relaxation of its muscles; 1 - membrana elastica interna; 2 - elastic fibers of tunicae mediae; 3 - membrana elastica ext.; 4 - elastic fibers of tunicae externae (according to Shchelkunov).

In different arteries, the degree of development of the elastic stroma is expressed differently. It reaches its highest development in the wall of the aorta and arteries extending from it, which have an elastic type of structure. In them, the elastic stroma is represented by an internal elastic membrane (membrana elastica interna), which lies on the border with the inner membrane and an external elastic membrane (membrana elastica externa), located outside the muscle layer (Fig. 2). Between the numerous layers of muscle cells there are also elastic fenestrated membranes (membranae fenestratae) that run in different directions. All these membranes and bundles of elastic fibers connected with them, which run longitudinally in the adventitia, constitute the elastic stroma of the arterial wall. Smooth muscle cells are connected to it with the help of argyrophilic fibrils and the main intermediate substance.

As the artery branches, the elastic stroma gradually becomes less pronounced. In an artery of medium and small caliber, only the inner and outer membranes remain in the elastic stroma, while between the layers of muscle cells, unlike the aorta, there are only thin networks of elastic fibers. In the smallest arteries, the elastic stroma is weakly expressed and is presented in the form of a delicate network of elastic fibers. In the wall of precapillary arterioles, it is completely lost, leaving only a network of thin argyrophilic fibrils and the main intermediate substance. Muscle cells in the wall of precapillary arterioles form one row and are circular (Fig. 3). When the precapillary arteriole passes into the capillary, they disappear, only the inner cell layer continues, which makes up the entire wall of the capillary, formed by the endothelium and the basal layer containing individual adventitial cells.

Outer shell - tunica externa (adventitia) It is built from loose connective tissue with a high content of elastic and collagen fibers. It performs the function of delimiting the arteries and protecting them. The outer shell of the arteries is rich in blood vessels and nerves.

The walls of the arteries have their own blood and lymphatic vessels (vasa vasorum, vasa lymphatica vasorum). Arteries supplying the walls of blood vessels originate from branches of nearby arteries, in particular from small arteries located in the connective tissue around the circumference of the supplied vessel and forming, due to the presence of a large number of anastomoses, the arterial plexus. Arterial branches penetrating through the adventitia into the thickness of the walls of the arteries form networks in it.

The outflow of venous blood from the wall of the artery is carried out into the nearby veins. Lymphatic vessels from the wall of the arteries are directed to the regional lymph nodes.

The arteries are innervated by branches of the sympathetic nerves and nearby spinal and cranial nerves. The issue of parasympathetic innervation of the arteries has not yet been resolved, although recently there have been studies stating the dual innervation of the carotid arteries, which is confirmed by the presence of cholinergic (E. K. Plechkova and A. V. Borodulya, 1972) and adrenergic fibers in their walls. The nerves of the arteries, which form plexuses in the adventitia, penetrate into the middle membrane and innervate its muscular elements. These nerves are called vasomotor - "vasomotors". Under the influence of "vasomotors" ("vasoconstrictors"), the muscle fibers of the arterial wall contract and narrow its lumen.

The walls of the arteries are equipped with numerous and diverse in structure and function of sensitive nerve endings - angioreceptors (chemoreceptors, pressoreceptors, etc.). In some parts of the arterial system there are zones of particularly high sensitivity, which are defined as reflexogenic zones, (see). In addition to the nerves of the arteries themselves, in the connective tissue surrounding the arteries, along the course of the latter, there are plexuses of autonomic nerves with nerve knots included in them, which, together with the branches of the corresponding artery, reach the organ they innervate.

Branching of large arteries into smaller ones occurs most often in three main types: main, loose or mixed (V. N. Shevkunenko and others). In the first type of branching from a large artery - the main - sequentially, along its length, branches depart; as the branches branch off, the arterial trunk decreases in diameter. In the second case, the vessel soon after its discharge is immediately divided into several branches. One and the same artery can branch according to the main or loose type, or its branching can have a transitional - mixed character. The main arterial trunks usually lie between the muscles, deep on the bones. According to P.F. Lesgaft, the arterial trunks are divided according to the bone basis. So, for example, there is one arterial trunk on the shoulder, two on the forearm, and five on the hand.

The arteries of some organs or areas have a tortuous, or spiral, course. This tortuosity is normal and occurs mainly in organs with varying volume or easily mobile. The spiral course has, for example, the splenic artery. With age, due to changes in the walls of the arteries, tortuosity increases or appears where it was not observed at a young age.

The arterial system as part of the cardiovascular system is characterized by the presence in all organs, areas and parts of the body of connections between arteries or their branches - anastomoses, thanks to which collateral circulation is carried out (see Vascular collaterals). With underdevelopment of one of the arteries supplying this organ, there is a compensatory development of the other artery with an increase in its caliber. Arteries that do not have anastomoses with neighboring trunks are often called terminal.

In addition to anastomoses, there are direct connections between arterial branches - fistulas between small arteries or arterioles and veins; through these anastomoses, blood passes from the arteries to the veins, bypassing the capillaries (see Arteriovenous anastomoses). The branching of arterial branches inside the organs and the distribution of the smallest branches in them - arterioles and precapillary arterioles in each organ, depending on its structure and functions, have their own characteristics. In the walls of hollow organs, they form plexuses and networks located in separate layers or between them. In parenchymal, glandular (mostly lobular) organs, arterial branches, together with veins, lymphatic vessels and nerves, lie in the connective tissue layers between the lobules (for example, in the liver). If an artery supplies blood to a part of an organ - a segment, it is called segmental (for example, in the lung, liver, kidney). To the muscles, arteries come from their inner side; to the nerves - at the place of their exit to the periphery and accompany the nerve. Arteries are subject to a large extent of individual variability - variations. Each artery varies in its position, course, number of branches it gives off, etc.

Research methods, Malformations, Diseases and damage to the arteries- see Blood vessels.

S. I. Shchelkunov, E. A. Vorobieva.

From the aorta (or from its branches) all the arteries of the systemic circulation begin. Depending on the thickness (diameter), the arteries are conditionally divided into large, medium and small. Each artery has a main trunk and its branches.

The arteries that supply blood to the walls of the body are called parietal (parietal), arteries of internal organs - visceral (visceral). Among the arteries, there are also extraorganic, carrying blood to the organ, and intraorganic, branching within the organ and supplying its individual parts (lobes, segments, lobules). Many arteries are named after the organ they supply (renal artery, splenic artery). Some arteries got their name in connection with the level of their discharge (beginning) from a larger vessel (superior mesenteric artery, inferior mesenteric artery); by the name of the bone to which the vessel is attached (radial artery); in the direction of the vessel (medial artery surrounding the thigh), as well as in depth (superficial or deep artery). Small vessels that do not have special names are designated as branches (rami).

On the way to the organ or in the organ itself, the arteries branch into smaller vessels. Distinguish the main type of branching of the arteries and loose. At trunk type there is a main trunk - the main artery and lateral branches extending from it. As the side branches depart from the main artery, its diameter gradually decreases. Loose type artery branching is characterized by the fact that the main trunk (artery) is immediately divided into two or more terminal branches, the general branching plan of which resembles the crown of a deciduous tree.

There are also arteries that provide roundabout blood flow, bypassing the main path, - collateral vessels. If movement along the main (main) artery is difficult, blood can flow through collateral bypass vessels, which (one or more) start either from a common source with the main vessel, or from different sources and end in a common vascular network.

Collateral vessels connecting (anastomosing) with branches of other arteries act as inter-arterial anastomoses. Distinguish intersystem interarterial anastomoses- connections (fistulas) between different branches of different large arteries, and intrasystemic interarterial anastomoses- connections between branches of one artery.

The wall of each artery consists of three membranes: internal, middle and external. The inner shell (tunica intima) is formed by a layer of endothelial cells (endotheliocytes) and a subendothelial layer. Endothelial cells lying on a thin basement membrane are flat thin cells connected to each other by means of intercellular contacts (nexuses). The perinuclear zone of endotheliocytes is thickened, protrudes into the lumen of the vessel. The basal part of the cytolemma of endotheliocytes forms numerous small branched processes directed towards the subendothelial layer. These processes pierce the basal and internal elastic membranes and form nexuses with smooth myocytes of the middle lining of the artery (myoepithelial junctions). subepithelial layer in small arteries (muscular type) thin, consists of the main substance, as well as collagen and elastic fibers. In larger arteries (muscle-elastic type), the subendothelial layer is better developed than in small arteries. The thickness of the subendothelial layer in elastic type arteries reaches 20% of the thickness of the vessel walls. This layer in large arteries consists of fine-fibrillar connective tissue containing unspecialized stellate cells. Sometimes longitudinally oriented myocytes are found in this layer. In the intercellular substance, glycosaminoglycans and phospholipids are found in large quantities. In middle-aged and elderly people, cholesterol and fatty acids are detected in the subendothelial layer. Outside of the subendothelial layer, on the border with the middle shell, the arteries have internal elastic membrane formed by densely intertwined elastic fibers and representing a thin continuous or intermittent (fenestrated) plate.

The middle shell (tunica media) is formed by smooth muscle cells of a circular (spiral) direction, as well as elastic and collagen fibers. In various arteries, the structure of the middle membrane has its own characteristics. So, in small arteries of the muscular type with a diameter of up to 100 microns, the number of layers of smooth muscle cells does not exceed 3-5. Myocytes of the middle (muscular) membrane are located in the elastin-containing ground substance that these cells produce. Muscle-type arteries have intertwining elastic fibers in the middle shell, thanks to which these arteries retain their lumen. In the middle layer of arteries of the muscular-elastic type, smooth myocytes and elastic fibers are distributed approximately equally. This membrane also contains collagen fibers and single fibroblasts. Arteries of the muscular type with a diameter of up to 5 mm. Their middle shell is thick, formed by 10-40 layers of spirally oriented smooth myocytes, which are connected to each other by means of interdigitations.

In the arteries of the elastic type, the thickness of the middle membrane reaches 500 microns. It is formed by 50-70 layers of elastic fibers (elastic fenestrated membranes), 2-3 microns thick each fiber. Between the elastic fibers are relatively short spindle-shaped smooth myocytes. They are oriented spirally, connected to each other by tight contacts. Around the myocytes are thin elastic and collagen fibers and an amorphous substance.

On the border of the middle (muscular) and outer shells there is a fenestrated outer elastic membrane, which is absent in small arteries.

The outer shell, or adventitia (tunica externa, s. adventicia), is formed by loose fibrous connective tissue, passing into the connective tissue of organs adjacent to the arteries. Vessels feeding the walls of the arteries (vascular vessels, vasa vasorum) and nerve fibers (vascular nerves, nervi vasorum) pass through the adventitia.

In connection with the structural features of the walls of arteries of different calibers, arteries of elastic, muscular and mixed types are distinguished. Large arteries, in the middle shell of which elastic fibers predominate over muscle cells, are called elastic type arteries(aorta, pulmonary trunk). The presence of a large number of elastic fibers counteracts excessive stretching of the vessel by blood during contraction (systole) of the ventricles of the heart. The elastic forces of the walls of arteries, filled with blood under pressure, also contribute to the movement of blood through the vessels during relaxation (diastole) of the ventricles. Thus, continuous movement is ensured - blood circulation through the vessels of the large and small circles of blood circulation. Part of the arteries of medium and all arteries of small caliber are muscular arteries. In their middle shell, muscle cells predominate over elastic fibers. The third type of arteries - mixed arteries(muscular-elastic), these include most of the middle arteries (carotid, subclavian, femoral, etc.). In the walls of these arteries, muscle and elastic elements are distributed approximately equally.

It should be borne in mind that as the caliber of the arteries decreases, all their membranes become thinner. The thickness of the subepithelial layer, the internal elastic membrane, decreases. The number of smooth myocytes of elastic fibers in the middle shell decreases, the outer elastic membrane disappears. In the outer shell, the number of elastic fibers decreases.

The topography of the arteries in the human body has certain patterns (P. Flesgaft).

1. Arteries are sent to the organs along the shortest path. So, on the limbs, the arteries run along a shorter flexion surface, and not along a longer extensor one.
2. The main significance is not the final position of the organ, but the place of its laying in the embryo. For example, to the testicle, which is laid in the lumbar region, a branch of the abdominal aorta, the testicular artery, is sent along the shortest path. As the testicle descends into the scrotum, the artery that feeds it descends along with it, the beginning of which in an adult is at a great distance from the testicle.
3. Arteries approach the organs from their inner side, facing the source of blood supply - the aorta or another large vessel, and in most cases the artery or its branches enter the organ through its gates.
4. There are certain correspondences between the structure of the skeleton and the number of main arteries. The spinal column accompanies the aorta, the clavicle - one subclavian artery. On the shoulder (one bone) there is one brachial artery, on the forearm (two bones - the radius and ulna) - two arteries of the same name.
5. On the way to the joints, the collateral arteries depart from the main arteries, and the recurrent arteries depart from the underlying sections of the main arteries towards them. Anastomosing among themselves along the circumference of the joints, the arteries form articular arterial networks that provide continuous blood supply to the joint during movement.
6. The number of arteries entering the organ and their diameter depend not only on the size of the organ, but also on its functional activity.
7. The patterns of branching of arteries in organs are determined by the shape and structure of the organ, the distribution and orientation of bundles of connective tissue in it. In organs with a lobular structure (lung, liver, kidney), the artery enters the gate and then branches, respectively, into lobes, segments and lobules. To the organs that are laid in the form of a tube (for example, the intestines, uterus, fallopian tubes), the feeding arteries approach from one side of the tube, and their branches have an annular or longitudinal direction. Entering the organ, the arteries branch many times to the arterioles.

The walls of blood vessels have abundant sensory (afferent) and motor (efferent) innervation. In the walls of some large vessels (the ascending part of the aorta, the aortic arch, bifurcation - the place where the common carotid artery branches into the external and internal, the superior vena cava and jugular veins, etc.), there are especially many sensitive nerve endings, which is why these areas are called reflexogenic zones. Virtually all blood vessels have abundant innervation, which plays an important role in the regulation of vascular tone and blood flow.

The human body consists of biological tissues permeated with a mass of blood vessels. They are responsible for the nutrition of cells and the removal of metabolites, supporting their vital activity. Arteries are a type of blood vessels that carry blood directly to the capillaries. All cells of the body receive solutes from them through the interstitial fluid.

Morphology

An artery is an anatomical structure in the form of an elastic tube with a wall and a lumen. It passes in body cavities or connective tissue veins of parenchymal organs, where it constantly gives off small branches to nourish the surrounding tissues. An artery is a vessel that constantly conducts a pulse wave.

In large vessels, its distribution is achieved mainly due to the elastic qualities of the wall, and in small vessels due to muscle contraction. Like the heart, arterial vessels are constantly in good shape and experience periods of stretching and contraction. The muscular wall also alternates periods of contraction with relaxation.

Histological structure

Any artery is a formation with a multilayer wall, which consists of elastic fibers intertwined with each other and muscle cells embedded between them. This is how the middle wall of the vessel is arranged, which is covered with a connective tissue membrane from the inside. It is based on the endothelial layer, facing the inside of the vessel. It is a single-layer protozoan epithelium, the cells of which fit tightly with their edges in order to prevent platelet cells from reaching the connective tissue membrane. The latter contains platelet adhesion receptors, which is the basis of the mechanism of thrombus formation in case of damage to the endothelial layer.

Outside the middle shell, represented by smooth muscle cells woven into an elastic network, there is another layer of connective tissue. It serves to ensure the mechanical strength of the artery. What is it in terms of histology? This shell is a strong network of embedded single cells. It is connected to a looser adventitia, which connects the artery with the stromal tissue of the parenchymal organs.

Regulation of arterial tone

All arterial vessels of the body have their own blood circulation, since only the endothelium can feed on the blood in their lumen. These vessels and nerves run in the outer connective tissue sheath and supply blood to the middle layer - the muscle cells. The smallest nerves of the autonomic system also go to them. They transmit sympathetic impulses that accelerate the conduction of the pulse wave with an increase in the heart rate.

In addition, the artery is a hormone-dependent structure that expands or narrows depending on the presence of humoral factors: adrenaline, dopamine, norepinephrine. Through them, the body regulates the tone of the entire vascular system. The main goal is to rapidly increase blood flow to the muscles by dilating peripheral blood vessels in the event of suprathreshold stress. This is an evolutionary mechanism for saving the life of an organism by fleeing from danger.

main arteries of the body

The largest artery that can withstand maximum pressure is the aorta - the main vessel, from which regional branches depart. The aorta originates in the left outflow tract of the corresponding ventricle. The pulmonary artery originates in the right outflow tract of the heart. This system demonstrates the separation of circulation circles: the aorta carries blood into a large circle, and the pulmonary trunk into a small one. Both of these vessels drain blood from the heart, and the veins deliver it to it, where the circulatory system is crossed.

Among the most important arteries of the body, renal, carotid, subclavian, mesenteric, and vessels of the extremities should be distinguished. Albeit not the largest, but extremely important for the body, coronary arteries stand separately. What does this mean and why are they special? Firstly, they nourish the heart and form two mutually perpendicular circles of blood circulation of this organ. Secondly, they are special because they are the only arterial vessels that fill in ventricular diastole before the development of the pulse wave of the ascending aorta.