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.