Nursing Preparation Study Guide

Nursing Preparation Study Guide

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 tissue consists of concentric layers. Muscle bundles that form figure eights wrap around the atria and encircle the great vessels within the atrial myocardium. Both ventricles are wrapped with superficial cardiac muscles, while deeper muscle layers spiral around and between the ventricles toward the apex in a figure-eight pattern.

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