The heart is housed within a fibroserous sac called the what?

The heart is housed within a fibroserous sac called the what?

• A. Pericardial sac
• B. Endocardial sac
• C. Myocardial sac
• D. Epicardial sac

Answer: (A)

The heart sits inside a protective fibroserous envelope called the pericardium, forming the pericardial sac. This enclosing structure has a tough outer fibrous layer that anchors the heart and a serous layer that folds inward to create a parietal layer lining the sac and a visceral layer that covers the heart surface (the epicardium). The small space between these serous layers contains fluid to minimize friction as the heart beats. The epicardium is the outer surface of the heart, not a separate sac, and the endocardium and myocardium refer to the inner lining and muscular wall of the heart, respectively.