Description
The heart is a muscular pump situated in the middle mediastinum. It is responsible for propelling blood to all parts of the body, either through the systemic or pulmonary circulatory systems. The heart is composed of four chambers, the left and right atria and left and right ventricles. The left and right atria are separated by an interatrial septum, and from the ventricles by atrioventricular valves (tricuspid and bicuspid valves); the left and right ventricles are separated by an interventricular septum.
The heart is enclosed within a fibroserous sac, the pericardium. The pericardium is composed of a tough outer fibrous layer and the inner serous layers, the parietal and visceral layers of the serous pericardium. The fibrous layer is attached to the sternum anteriorly, the central tendon of the diaphragm inferiorly, the vertebral column posteriorly, the mediastinal pleural laterally, and to the outer layer of the base of the great vessels. However, it’s not attached to the heart itself. The outer parietal layer of the serous pericardium adhers to the internal surface of the fibrous layer; while the inner visceral layer is adherent to the heart as the epicardium. Between the two serous layers is a potential space called the pericardial sac, which contains serous fluid. The pericardium ensures stability for the heart by attaching to surrounding structures mentioned above. It also provides a physical limit to cardiac distension and a barrier to the spread of infection. Additionally, the serous layer produces fluid, which enables friction-free movement of the heart.
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Pericardium
The pericardium (from the Greek πɛρι´, “around” and κa´ρδιον, “heart”) is a double-walled sac containing the heart and the roots of the great vessels.
