What is the outer layer of the heart wall called?

The correct answer is the epicardium, which is the outer layer of the heart wall. The epicardium is a thin layer of tissue that serves both as a protective barrier and as a part of the heart’s structure, closely adhering to the underlying myocardium, the muscular middle layer of the heart wall.

In the context of cardiac anatomy, the epicardium plays a crucial role in housing the coronary blood vessels that supply the heart muscle with nutrients and oxygen. Its smooth surface also helps reduce friction between the heart and surrounding structures, particularly during the heart's rhythmic contractions.

It’s important to distinguish the epicardium from the endocardium, which is the inner layer lining the chambers of the heart; the myocardium, which is the muscular layer responsible for contracting and pumping blood; and the pericardium, which is a fibrous sac surrounding the heart that offers additional protection and anchors the heart in the thoracic cavity. Understanding these layers is essential for interpreting EKG findings and their implications for heart health.