What is the sac of connective tissue surrounding the heart called?

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

Answer: (B)

A protective sac surrounds the heart. This outer fibrous tissue wrapping is called the pericardium. It forms a double-layered sac with a parietal layer that lines the cavity and a visceral layer that hugs the heart itself (the visceral layer is the epicardium, part of the heart wall). Inside the heart, the layers are the myocardium, which is the muscular wall, and the endocardium, which lines the heart chambers. The pericardial space between the layers contains a small amount of lubricating fluid to reduce friction as the heart beats, helping it move smoothly and stay anchored in the chest.