Which layer is the outer layer of the pericardial sac?

Which layer is the outer layer of the pericardial sac?

• A. Fibrous pericardium
• B. Serous pericardium
• C. Endocardium
• D. Myocardium

Answer: (A)

The outer boundary of the pericardial sac is the fibrous pericardium. This tough, dense connective tissue layer encases the heart and the roots of the great vessels, provides protection, and anchors the heart to surrounding structures such as the diaphragm and sternum, helping prevent overexpansion. Beneath it lies the serous pericardium, which is a thinner membrane that forms a parietal layer lining the fibrous sac and a visceral layer covering the heart itself, with a small fluid-filled space between them to reduce friction. The endocardium lines the interior chambers of the heart, and the myocardium is the thick muscular wall of the heart.

The outer boundary of the pericardial sac is the fibrous pericardium. This tough, dense connective tissue layer encases the heart and the roots of the great vessels, provides protection, and anchors the heart to surrounding structures such as the diaphragm and sternum, helping prevent overexpansion. Beneath it lies the serous pericardium, which is a thinner membrane that forms a parietal layer lining the fibrous sac and a visceral layer covering the heart itself, with a small fluid-filled space between them to reduce friction. The endocardium lines the interior chambers of the heart, and the myocardium is the thick muscular wall of the heart.