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 is housed within a fibroserous sac called the pericardium. This structure has a tough outer fibrous layer and an inner serous layer that folds back to form the parietal layer lining the sac and the visceral layer that covers the heart itself. The space between these serous layers, the pericardial cavity, contains a small amount of fluid to reduce friction as the heart beats, helping protect and stabilize the heart within the chest. Endocardial refers to the lining inside the heart chambers, not a surrounding sac. Myocardial describes the heart muscle itself, not a enclosing sac. The epicardium is the outer surface layer of the heart, part of the serous pericardium, but it is not a separate enclosing sac. So the enclosing structure is the pericardium.

The heart is housed within a fibroserous sac called the pericardium. This structure has a tough outer fibrous layer and an inner serous layer that folds back to form the parietal layer lining the sac and the visceral layer that covers the heart itself. The space between these serous layers, the pericardial cavity, contains a small amount of fluid to reduce friction as the heart beats, helping protect and stabilize the heart within the chest.

Endocardial refers to the lining inside the heart chambers, not a surrounding sac. Myocardial describes the heart muscle itself, not a enclosing sac. The epicardium is the outer surface layer of the heart, part of the serous pericardium, but it is not a separate enclosing sac. So the enclosing structure is the pericardium.