Which heart layer is responsible for contraction and forms the muscular wall?

Which heart layer is responsible for contraction and forms the muscular wall?

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

Answer: (A)

The heart's muscular wall is the myocardium, the contractile layer of cardiac muscle. Its cells are connected in a network through intercalated discs and gap junctions, which lets electrical impulses sweep quickly and coordinate a strong, unified contraction to pump blood. The myocardium is especially thick in the ventricles to generate the pressure needed to push blood to the lungs and the rest of the body. The endocardium lines the interior chambers and valves, but it is not muscular. The epicardium covers the outer surface of the heart as a thin layer, and the parietal pericardium is part of the surrounding pericardial sac, not heart muscle.

The heart's muscular wall is the myocardium, the contractile layer of cardiac muscle. Its cells are connected in a network through intercalated discs and gap junctions, which lets electrical impulses sweep quickly and coordinate a strong, unified contraction to pump blood. The myocardium is especially thick in the ventricles to generate the pressure needed to push blood to the lungs and the rest of the body. The endocardium lines the interior chambers and valves, but it is not muscular. The epicardium covers the outer surface of the heart as a thin layer, and the parietal pericardium is part of the surrounding pericardial sac, not heart muscle.