Learn to visualize the underlying structures of the heart as you examine the anterior chest. Understanding cardiac anatomy and physiology is particularly important in the examination of the cardiovascular system.
Note that the right ventricle occupies most of the anterior cardiac surface. This chamber and the pulmonary artery form a wedgelike structure behind and to the left of the sternum.
The inferior border of the right ventricle lies below the junction of the sternum and the xiphoid process. The right ventricle narrows superiorly and meets the pulmonary artery at the level of the sternum or "base of the heart"—a clinical term that refers to the right and left 2nd interspaces close to the sternum.
The left ventricle, behind the right ventricle and to the left, forms the left lateral margin of the heart. Its tapered inferior tip is often termed the cardiac "apex." It is clinically important because it produces the apical impulse, sometimes called the point of maximal impulse, or PMI.* This impulse locates the left border of the heart and is usually found in the 5th interspace 7 cm to 9 cm lateral to the midsternal line. It is about the size of a quarter, roughly 1 to 2.5 cm in diameter.
The right heart border is formed by the right atrium, a chamber not usually identifiable on physical examination. The left atrium is mostly posterior and cannot be examined directly, although its small atrial appendage may make up a segment of the left heart border between the pulmonary and the left ventricle.
Above the heart lie the great vessels. The pulmonary artery, already mentioned, bifurcates quickly into its left and right branches. The aorta curves upward from the left ventricle to the level of the sternal angle, where it arches backward to the left and then down. On the right, the superior vena cava empties into the right atrium.
Although not illustrated, the inferior vena cava also empties into the right atrium. The superior and inferior venae cavae carry venous blood to the heart from the upper and lower portions of the body.
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