Heart topography.
The heart is located in the anterior mediastinum asymmetrically. Most of it is to the left of the median line, only the right atrium and both vena cava remain to the right. The long axis of the heart is located obliquely from top to bottom, from right to left, back to front, forming an angle of approximately 40 ° with the axis of the whole body. At the same time, the heart is turned in such a way that its right venous section lies more anteriorly, the left arterial section lies posteriorly.
The heart together with the pericardium in most of its anterior surface (facies sternocostalis) is covered with lungs, the anterior edges of which, together with the corresponding parts of both pleura, coming in front of the heart, separate it from the anterior chest wall, except for one place where the anterior surface of the heart is through the pericardium adjacent to the sternum and cartilage of the V and VI ribs. The borders of the heart are projected on the chest wall as follows. The push of the apex of the heart can be palpated 1 cm internally from linea mamillaris sinistra in the fifth left intercostal space. The upper limit of the cardiac projection is at the level of the upper edge of the third costal cartilage. The right border of the heart extends 2–3 cm to the right of the right edge of the sternum, from the third to the fifth rib; the lower boundary goes transversely from the V right costal cartilage to the apex of the heart, the left border from the cartilage of the III rib to the apex of the heart.
The ventricular outlets (aorta and pulmonary trunk) lie on the level III of the left costal cartilage; pulmonary trunk (ostium trunci pulmonalis) – at the sternal end of this cartilage, aorta (ostium aortae) – behind the sternum somewhat to the right. Both ostia atrioventricularia are projected on a straight line running along the sternum from the third left to the fifth right intercostal space.
During auscultation of the heart (listening to the tones of the valves using a phonendoscope), the tones of the heart valves are heard in certain places: mitral – at the apex of the heart; tricuspid – on the sternum to the right against the V costal cartilage; the tone of the aorta valves – at the edge of the sternum in the second intercostal space on the right; the tone of the pulmonary valves – in the second intercostal space to the left of the sternum.