Intraorganic arteries of the heart

Intraorganic arteries of the heart

The first one descends along the anterior interventricular sulcus to the apex of the heart, where it anastomoses with the branch of the right coronary artery. The second, continuing the main trunk of the left coronary artery, bends around the coronary sulcus the heart on the left side and also connects to the right coronary artery. As a result, an arterial ring located in the horizontal plane is formed along the entire coronary sulcus, from which the branches go to the heart perpendicularly. The ring is a functional device for the collateral circulation of the heart. The branches of the left coronary artery vascularize the left, atrium, the entire anterior wall and most of the posterior wall of the left ventricle, part of the anterior wall of the right ventricle, anterior 2/3 of the interventricular septum and the anterior papillary muscle of the left ventricle.

Different variants of the development of coronary arteries are observed, as a result of which there are various ratios of blood supply pools. From this point of view, there are three forms of blood supply to the heart: uniform, with the same development of both coronary arteries, left-handed and right-handed. In addition to the coronary arteries, “additional” arteries from the bronchial arteries, from the lower surface of the aortic arch near the arterial ligament, approach the heart, which is important to take into account in order not to damage them during operations on the lungs and esophagus and not to impair the blood supply to the heart.

The branches of the atria (rr. Atriales) and their ears (rr. Auriculares), the branches of the ventricles (rr. Ventriculares), and the partition walls (rr. Septales anteriores et posteriores) depart from the trunks of the coronary arteries and their large branches, respectively. Having infiltrated into the myocardium, they branch out according to the number, location and arrangement of its layers: first in the outer layer, then on average (in the ventricles) and finally in the inner, then penetrate the papillary muscles (aa. Papillares) and even in the atrial ventricular valves The intramuscular arteries in each layer follow the course of the muscle bundles and anastomose in all layers and parts of the heart.

Some of these arteries have a highly developed layer of involuntary muscles in their walls, with their reduction, a complete closure of the vessel lumen occurs, which is why these arteries are called “closing”. A temporary spasm of the “closure” arteries may result in cessation of blood flow to a given area of ​​the heart muscle and cause myocardial infarction.

Blood supply of the heart. The power of the heart.

Blood supply of the heart. The power of the heart.

Arteries of the heart – aa. coronariae dextra et sinistra, coronary arteries, right and left, start from bulbus aortae below the upper edges of the semilunar valves. Therefore, during systole, the entrance to the coronary arteries is covered with valves, and the arteries themselves are compressed by the contracted muscle of the heart. As a consequence, during systole, the blood supply to the heart decreases: blood enters the coronary arteries during diastole, when the inlets of these arteries, located in the aortic mouth, are not closed by the semilunar valves.

The right coronary artery emerges from the aorta, respectively, the right semilunar valve and lies between the aorta and the ear of the right atrium, outwards from which it bends around the right edge of the heart along the coronary sulcus and passes to its posterior surface. Here it continues into the interventricular branch, r. interventricularis posterior. The latter descends along the posterior interventricular groove to the apex of the heart, where it anastomoses with the branch of the left coronary artery.

The branches of the right coronary artery vascularize: the right atrium, part of the anterior wall and the entire posterior wall of the right ventricle, a small portion of the posterior wall of the left ventricle, interatrial septum, posterior third of the interventricular septum, papillary muscles of the right ventricle and posterior papillary muscle of the left ventricle. ,

The left coronary artery, coming out of the aorta at the left lunate flap, also lies in the coronary groove anterior to the left atrium. Between the pulmonary trunk and the left ear, it gives two branches: a thinner anterior, interventricular, ramus interventricularis anterior, and a larger left, envelope, ramus circumflexus.

Conductive system of the heart. Innervation of the heart.

Conductive system of the heart. Innervation of the heart.

The so-called cardiac conduction system plays an important role in the rhythmic work of the heart and in the coordination of the muscles of the individual chambers of the heart. Although the muscles of the atria are separated from the muscles of the ventricles by fibrous rings, however, there is a connection between them by means of the conduction system, which is a complex neuromuscular formation. The muscle fibers that make up it (conductive fibers) have a special structure: their cells are poor in myofibers and rich in sarcoplasm, therefore lighter. They are sometimes visible to the naked eye in the form of light colored threads and represent a less differentiated part of the original syncytium, although they are larger in size than the ordinary muscle fibers of the heart. In the conducting system there are knots and bundles.

1. The sinoatrial node, nodus sinuatrialis, is located in the wall section of the right atrium corresponding to the cold-blooded sinus venosus (in sulcus terminalis, between the superior vena cava and the right ear). It is associated with atrial musculature and is important for their rhythmic contraction.

2. The atrioventricular node, nodus atrioventricularis, is located in the wall of the right atrium, near the tricuspid cuspis septalis. Fibers of the node, directly connected with the muscles of the atrium, continue into the septum between the ventricles in the form of the atrioventricular bundle, fasciculus atrioventricularis (His bundle). In the septum of the ventricles, the bundle is divided into two legs – crus dextrum et sinistrum, which go into the walls of the co-named ventricles and branch under the endocardium in their muscles. The atrioventricular bundle is very important for the functioning of the heart, since it transmits a wave of contraction from the atria to the ventricles, thereby establishing regulation of the rhythm of systole — the atria and ventricles.

Consequently, the atria are interconnected by the sinoatrial node, and the atria and the ventricles are connected by the atrioventricular bundle. Usually, irritation from the right atrium is transmitted from the sinus node to the atrioventricular node, and from it through the atrioventricular bundle to both ventricles.

The structure of the walls of the heart. Myocardium.

The structure of the walls of the heart. Myocardium.

The walls of the heart consist of 3 membranes: the inner endocardium, the middle myocardium, and the outer epicardium, which is the pericardium visceral leaflet, pericardium. The thickness of the walls of the heart is formed mainly by the middle sheath, myocardium, myocardium, consisting of cardiac striated muscle tissue. The outer sheath, epicardium, is a serous coat. The inner lining, endocardium, endocardium, lines the cavity of the heart.

Myocardium, myocardium, or muscular tissue of the heart, although it has a transverse striation, but differs from skeletal muscles in that it is not composed of individual multicore fibers, but is a network of mononuclear cells — cardiomyocytes. In the musculature of the heart there are two sections: the muscle layers of the atrium and the muscle layers of the ventricles. The fibers of those and others start from two fibrous rings – anulifibrosi, of which one surrounds ostium atrioventriculare dextrum, the other – ostium atrioventriculare sinistrum. Since the fibers of one section, as a rule, do not pass into the fibers of another, the result is the possibility of reducing the atria separately from the ventricles. In the atria, the superficial and deep muscular layers are distinguished: the superficial consists of circular or transversely located fibers, deep – from the longitudinal, which with their ends begin from the fibrous rings and loop around the atrium. Around the circumference of large venous trunks, flowing into the atria, there are circular fibers covering them, like sphincters. Fibers of a superficial layer cover both auricles, deep belong separately to each auricle.

The muscles of the ventricles are even more complex. Three layers can be distinguished in it: a thin surface layer is composed of longitudinal fibers that start from the right fibrous ring and go obliquely downwards, passing to the left ventricle; at the apex of the heart, they form a curl, vortex cordis, bending here loop-like in depth and forming the inner longitudinal layer, the fibers of which are attached to the fibrous rings with their upper ends. The fibers of the middle layer, located between the longitudinal outer and inner, go more or less circularly, and, unlike the surface layer, they do not pass from one ventricle to another, but are independent for each ventricle.

Left ventricle

Left ventricle

The left ventricle, ventriculus sinister, has the shape of a cone, the walls of which are 2–3 times as thick as the walls of the right ventricle (10–15 mm versus 5–8 mm). This difference is due to the muscular layer and is explained by the greater work done by the left ventricle (circulatory circle) compared to the right one (small circle). The thickness of the walls of the atria according to their function is even less significant (2 – 3 mm). The hole leading from the cavity of the left atrium to the left ventricle, octal ostium atrioventriculare sinistrum, is equipped with a left atrial-ventricular (mitral) valve, valva atrioventricularis sinistra (mitralis), of the two valves of which is smaller on the left and behind (cuspis posterior), – right and front (cuspis anterior). The free edges of the leaf are turned into the cavity of the ventricle, and chordae tendineae are attached to them. Musculi papillares are in the left ventricle, two in number – anterior and posterior; each papillary muscle gives the tendon threads of one or the other valvae mitralis valve. The aortic opening is called ostium aortae, and the nearest ventricular branch is conus arteriosus.

The aortic valve, valva aortae, has the same structure as the valve of the pulmonary trunk. One of the flaps, valvula semilunaris posterior, occupies the posterior third of the aortic circumference; the other two, valvulae semilunares dextra et sinistra, are the right and left sides of the hole. Nodules on their free edges, noduli valvularum semilunarium aortae, are more pronounced than on valves of the pulmonary trunk; lunulae valvularum semilunarium aortae are also available.

The septum between the ventricles, septum interventriculare, is represented mainly by muscle tissue, pars muscularis, except for the uppermost part, where there is only fibrous tissue covered on both sides with the endocardium, pars membranasea. Pars membranacea corresponds to the site of incomplete development of the interventricular septum of animals. There are often anomalies in the form of defects in the septum.

Right ventricle.

Right ventricle.

The right ventricle, ventriculus dexter, has the shape of a triangular pyramid, the base of which, facing up, is occupied by the right atrium, with the exception of the upper left corner, where the pulmonary trunk emerges from the right ventricle, truncus pulmonalis. The ventricular cavity is divided into two sections: the department closest to the ostium atrioventriculare and the anterior-superior section closest to the ostium trunci pulmonalis, conus arteriosus, which continues into the pulmonary trunk.

Ostium atrioventriculare dextrum, leading from the cavity of the right atrium to the cavity of the right ventricle, is equipped with a tricuspid valve, valva atrioventricularis dextra s. valva tricuspidalis, which makes it impossible for blood to return to the atrium during systole; blood is sent to the pulmonary trunk. Three valve leaflets are designated by their location as cuspis anterior, cuspis posterior, and cuspis septalis. The free edges of the leaf turn into the ventricle. Attached to them are thin tendon threads, chordae tendineae, which at their opposite ends are attached to the tips of the papillary muscles, the musculi papillares. The papillary muscles are cone-shaped muscular eminences, with their tips projecting into the cavity of the ventricle and passing into its walls with bases. In the right ventricle, there are usually three papillary muscles: the anterior, the largest in size, gives rise to tendon threads to the anterior and posterior cusps of the tricuspid valve; the posterior one, smaller in size, sends the tendinous filaments to the posterior and septal flaps and, finally, m. papillaris septalis, not always available muscle, gives tendon threads usually to the anterior cusp. In case of its absence, the filaments arise directly from the wall of the ventricle. In the area of ​​the conus arteriosus, the wall of the right ventricle is smooth, the fleshy trabeculae, trabeculae carneae, enter the rest of the length.

Blood from the right ventricle enters the pulmonary trunk through the ostium trunci pulmonalis, equipped with a valve, valva trunci pulmonalis, which prevents the return of blood from the pulmonary trunk back to the right ventricle during diastole. The valve consists of three semi moon flaps. Of these, one is attached to the anterior third of the circumference of the pulmonary trunk (valvula semilunaris anterior) and two to the back (valvulae semilunares dextra et sinistra). On the inner free edge of each flap there is a small nodule in the middle, nodulus valvulae semilunaris, on the sides of the knot the thin marginal segments of the flap are called lunulae valvulae semilunaris. Nodules contribute to a tighter closing of the flaps.

Chambers of the heart. Right atrium. Left atrium.

Chambers of the heart. Right atrium. Left atrium.

The atria are blood-receiving chambers, the ventricles, in contrast, eject blood from the heart into the arteries. The right and left atria are separated from each other by a septum, as well as the right and left ventricles. On the contrary, between the right atrium and the right ventricle there is a message in the form of a right atrioventricular opening, ostium atrioventriculare dextrum; between the left atrium and the left ventricle – ostium atrioventriculare sinistrum. Through these holes, blood during atrial systole is directed from the cavities of the latter into the cavity of the ventricles.

The right atrium, the atrium dextrum, is shaped like a cube. Behind him pour in at the top v. cava superior and v. below. cava inferior, anterior to the anterior to the hollow process – right ear, auricula dextra. The right and left ears cover the base of the aorta and pulmonary trunk. The partition between the atria, septum interatriale, set obliquely, from the front wall it goes back and to the right, so that the right atrium is located on the right and front, and the left – on the left and behind. The inner surface of the right atrium is smooth, with the exception of a small area in front and the inner surface of the ear, where a number of vertical ridges from the comb muscles, musculi pectinati, are visible. At the top of the musculi pectinati end with a scallop, crista terminalis, which on the outer surface of the atrium corresponds to sulcus terminalis. This sulcus indicates the junction of the primary sinus venosus with the atrium of the embryo. On the septum separating the right atrium from the left, there is an oval-shaped recess – fossa ovalis, which is bounded at the top and front by the edge – limbus fossae ovalis. This recess is the remainder of the hole – foramen ovale, through which the atria during the prenatal period communicate with each other. In cases of foramen ovale lasts for a lifetime, as a result of which it is possible to periodically shift arterial and venous blood in the event that the contraction of the atrial septum does not close it. There is a slight elevation between the openings of the upper and lower hollow veins on the back wall, tuberculum intervenosum, behind the upper fossae ovalis. It is believed that he directs the blood flow from the superior vena cava to the ostium atrioventriculare dextrum at the embryo.

From the bottom edge of the hole v. cava inferior to limbus fossae ovalis stretches a crescent-shaped fold, varying in size, valvula venae cavae inferioris. It is of great importance in the embryo, directing blood from the inferior vena cava through the foramen ovale to the left atrium. Below this flap, between the holes v. cava inferior and ostium atrioventriculare dextrum, sinus coronarius cordis flows into the right atrium, collecting blood from the veins of the heart; in addition, small veins of the heart, independently flow into the right atrium. Their small holes, foramina vendrum minimorum, are scattered on the surface of the walls of the atrium. Near the opening of the venous sinus there is a small fold of the endocardium, valvula sinus corondrii. In the lower anterior part of the atrium, the wide right atrioventricular ostium, ostium atrioventriculare dextrum, leads into the cavity of the right ventricle.

The left atrium, atrium sinistrum, is adjacent to the posterior descending aorta and esophagus. On each side, two pulmonary veins flow into it; the left ear, auricula sinistra, bulges anteriorly, bending around the left side of the aortic trunk and pulmonary trunk. In the ear there are musculi pectinati. In the inferior anterior left atrial ventricular opening, ostium atrioventriculare sinistrum, oval in shape leads to the cavity of the left ventricle.

Anatomy: Heart. The structure of the heart.

Anatomy: Heart. The structure of the heart.

The heart, cor, is a hollow muscular organ that takes blood from venous trunks poured into it and drives blood into the arterial system. The cavity of the heart is subdivided into 4 chambers: 2 atria and 2 ventricles. The left atrium and the left ventricle together form the left, or arterial, heart according to the properties of the blood in it; the right atrium and the right ventricle make up the right or venous heart. The contraction of the walls of the heart chambers is called systole, and their relaxation is diastole.

The heart has the shape of a somewhat flattened cone. It distinguishes apex, apex, base, basis, anterior-upper and lower surfaces and two edges – right and left, separating these surfaces.

The rounded apex of the heart, apex cordis, faces downward, forward and to the left, reaching the fifth intercostal space at a distance of 8–9 cm to the left of the midline; the apex of the heart is formed entirely by the left ventricle. The base, basis cordis, is facing up, back and to the right.

It is formed by the atria and in front by the aorta and the pulmonary trunk. In the upper right corner of the quadrilateral formed by the atria, there is a place – the occurrence of the superior vena cava, in the inferior – the inferior vena cava; now to the left are the places of entry of the two right pulmonary veins, on the left edge of the base – the two left pulmonary veins. The anterior, or sterno-costal, surface of the heart, facies sternocostalis, is anterior, upward and leftward and lies behind the body of the sternum and cartilage ribs from III to VI. The coronary sulcus, sulcus coronarius, which runs transversely to the longitudinal axis of the heart and separates the atria from the ventricles, the heart divides into the upper portion formed by the atria and the larger lower ventricle.

The anterior longitudinal sulcus, running along the facies sternocostalis, sulcus interventricularis anterior, runs along the border between the ventricles, with the greater part of the anterior surface forming the right ventricle and the smaller one the left.

The lower, or diaphragmatic, surface, facies diaphragmatica, is adjacent to the diaphragm, to its tendon center. On it passes the posterior longitudinal groove, sulcus interventricularis posterior, which separates the surface of the left ventricle (large) from the surface of the right (smaller). The anterior and posterior interventricular furrows of the heart with their lower ends merge with each other and form on the right edge of the heart, immediately to the right of the apex of the heart, a heart tenderloin, incisura apicis cordis. The edges of the heart, right and left, different configuration: right more acute; the left edge is rounded, more dull due to the greater thickness of the wall of the left ventricle.

Collateral circulation. Anastomosis. Collateral

Collateral circulation. Anastomosis. Collateral

Collateral circulation is an important functional adaptation of the body, associated with the high plasticity of blood vessels and ensuring uninterrupted blood supply to organs and tissues. His deep study, which has important practical significance, is connected with the name of V.N. Tonkov and his school.

By collateral circulation is meant a lateral, roundabout blood flow through the lateral vessels. It takes place under physiological conditions with temporary impairment of blood flow (for example, when blood vessels are compressed in places of movement, in joints). It can also occur in pathological conditions during blockage, injuries, ligation of vessels during operations, etc.

Under physiological conditions, a roundabout flow of blood is carried out along lateral anastomoses running parallel to the main one. These lateral vessels are called collaterals (for example, a. Collateralis ulnaris, etc.), hence the name of the bloodstream “roundabout”, or collateral, circulation.

When blood flow is obstructed through the main vessels, caused by blockage, damage or ligation during operations, the blood rushes through the anastomoses into the nearest lateral vessels, which expand and become crimped, their vascular wall is rebuilt due to changes in the muscle membrane and elastic frame and they are gradually transformed into collaterals other structure than normal.

Thus, collaterals exist under normal conditions, and can develop again in the presence of anastomoses. Consequently, in case of breakdown of the normal blood circulation caused by an obstacle to the flow of blood in a given vessel, the existing bypass circulatory pathways, the collaterals, first turn on, and then new ones develop. As a result, impaired blood circulation is restored. In this process, an important role is played by the nervous system.

From the above follows the need to clearly define the difference between anastomoses and collaterals.

Anastomosis (from the Greek. Anastomos – I supply the mouth) – fistula, every third vessel that connects the other two; This concept is anatomical.

Collateral (from lat. Collateralis – side) – side vessel carrying out a roundabout flow of blood; The concept of this anatomical and physiological.
Collaterals are of two kinds. Some exist in the norm and have the structure of a normal vessel, as well as the anastomosis. Others develop again from the anastomoses and acquire a special structure.

To understand the collateral circulation, it is necessary to know those anastomoses that interconnect systems of different vessels, which establish a collateral flow of blood in the event of vascular injuries, ligation during operations and blockage (thrombosis and embolism).

Anastomoses between the branches of large arterial highways supplying the main parts of the body (aorta, carotid arteries, subclavian, iliac, etc.) and representing, as it were, separate vascular systems, are called intersystem ones. Anastomoses between the branches of one large arterial highway, limited to the limits of its branching, are called intrasystem. These anastomoses have already been noted in the course of the presentation of the arteries.

There are anastomoses and between the thinnest intraorgan arteries and veins – arteriovenous anastomoses. According to them, blood flows around the microcirculatory bed when it overflows and, thus, forms a collateral path directly connecting the arteries and veins, bypassing the capillaries.

In addition, thin arteries and veins accompanying the great vessels in the neurovascular bundles and constituting the so-called perivascular and circulatory arterial and venous channels take part in the collateral circulation.

Anastomoses, besides their practical significance, are an expression of the unity of the arterial system, which, for the convenience of studying, we artificially divide into separate parts.

Arteries ligaments. Arteries of the brain.

Arteries ligaments. Arteries of the brain.

The content of the body includes its vascular system, which is part of the body as a whole. Therefore, the nature of the intraorgan arterial bed and the architectonics of the intraorgan arteries correspond to the structure, function, and development of the organ in which these vessels branch out (M. G. Prives). This explains that in different organs the arterial bed is constructed differently, and in similar organs it is approximately the same.

Brain arteries also go from the periphery to the center, and:
a) in the cerebral cortex (screen centers) they have the form of straight and short arteries,
b) in the white matter – direct and long, running along the nerve bundles, and c) vascular networks form in the subcortical nuclei (nuclear centers). In the nerve roots and nerves, the arteries run in endoneurium layers in parallel to the bundles of nerve fibers, to which, like in muscles, they are delivered perpendicular branches, forming longitudinal loops extending along the nerve bundles.

Thus, in organs built from a system of fibers (muscles, ligaments, nerves), the arteries are about the same: they enter in several places along the length of the organ and are located along the fibers. For the nutrition of this organ, not only the arteries that enter directly into it, but also the neighboring ones that give blood through the anastomosis are important. All the arteries of a given organ and its surrounding formations constitute the “organ system of vessels”.