Pericardium is:

Pericardium is:

• A. The muscular layer of the heart wall.
• B. A thin layer that lines the surface of the heart.
• C. The fibrous sac that encloses the heart.
• D. A thin layer that lines the inside of the heart.

Answer: (C)

The pericardium is the protective sac around the heart. It has an outer tough layer called the fibrous pericardium that forms the enclosing sac, plus a serous layer that lines the inside of that sac (parietal) and covers the heart itself (visceral, or epicardium). The option describing the fibrous sac that encloses the heart correctly identifies the main anatomical feature of the pericardium. The other structures are different parts of the heart’s walls or its inner lining: the muscular layer of the heart wall is the myocardium; the thin layer that lines the surface of the heart is the epicardium (visceral layer of the serous pericardium); and the thin layer that lines the inside of the heart is the endocardium.

The pericardium is the protective sac around the heart. It has an outer tough layer called the fibrous pericardium that forms the enclosing sac, plus a serous layer that lines the inside of that sac (parietal) and covers the heart itself (visceral, or epicardium). The option describing the fibrous sac that encloses the heart correctly identifies the main anatomical feature of the pericardium.

The other structures are different parts of the heart’s walls or its inner lining: the muscular layer of the heart wall is the myocardium; the thin layer that lines the surface of the heart is the epicardium (visceral layer of the serous pericardium); and the thin layer that lines the inside of the heart is the endocardium.