Nursing Entrance Exam

increased production of pericardial fluid. Fluid then collects in the pericardial cavity, restricting the movement of the heart. This condition, called cardiac tamponade, can also be caused by traumatic injuries (such as stab wounds) that produce bleeding into the pericardial cavity. 7.4.2 Superficial Anatomy of the Heart There are four cardiac chambers that can be identified in a superficial view of the heart. The two superior chambers are the atria. Anatomically, the atria have thin, muscular walls and are highly expandable to allow the chamber to be filled. When not filled with blood, the outer portion of each atrium resembles a deflated and wrinkled flap. Each atrium has an atrial appendage, or an auricle, which is an expandable extension that appeared to be ear-like, according to early anatomists. The border between the superior chambers and inferior chambers is a deep groove known as the coronary sulcus. The inferior chambers are the ventricles. The anterior interventricular sulcus and the posterior interventricular sulcus, which are shallower depressions, mark the boundary between the left and right ventricles.

7.4.3 The Heart Wall When dissected, the wall of the heart reveals three distinct layers: an outer epicardium, a middle myocardium, and an inner endocardium. 1. The epicardium covers the outer surface of the heart as the visceral pericardium. This serous membrane consists of an exposed mesothelium and an underlying layer of loose, areolar connective tissue that adheres to themyocardium. 2. Themyocardiumdefines themuscle layer that forms the bulk of both atria and ventricles. This layer contains cardiac muscle tissue, blood vessels, and nerves. The cardiac muscle

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