Which heart structure forms the outer protective sac around the heart?

Which heart structure forms the outer protective sac around the heart?

• A. Endocardium
• B. Pericardium
• C. Myocardium
• D. Endothelium

Answer: (B)

The outer protective sac around the heart is the pericardium. It surrounds and protects the heart, anchoring it in the chest and providing a lubricated cavity to reduce friction during beating. The pericardium has two parts: the tough fibrous layer that anchors the heart and a serous layer that forms the pericardial cavity with fluid between layers. The other options describe different heart structures that aren’t protective coverings. The endocardium lines the inside of the heart chambers; the myocardium is the thick muscular wall of the heart; the endothelium lines the interior surfaces of blood vessels and the heart.

The outer protective sac around the heart is the pericardium. It surrounds and protects the heart, anchoring it in the chest and providing a lubricated cavity to reduce friction during beating. The pericardium has two parts: the tough fibrous layer that anchors the heart and a serous layer that forms the pericardial cavity with fluid between layers.

The other options describe different heart structures that aren’t protective coverings. The endocardium lines the inside of the heart chambers; the myocardium is the thick muscular wall of the heart; the endothelium lines the interior surfaces of blood vessels and the heart.