Which layer is the inner lining of the heart chambers and covers the surface of the valves?

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

Answer: (A)

The inner lining of the heart chambers and the surfaces of the valves is the endocardium. This layer sits closest to the blood inside the heart and is made of endothelial cells, providing a smooth, low-friction surface that helps blood flow and reduces clot formation. It also forms the continuous lining with the endothelium of all blood vessels entering and leaving the heart.

Beyond this innermost layer lies the myocardium, the muscular wall responsible for pumping. Outside that is the epicardium, the thin outer layer that sometimes contains fat and houses coronary vessels. Surrounding the heart is the pericardium, a fibrous sac that encases the heart.