The muscular middle layer of the heart is known as which?

The muscular middle layer of the heart is known as which?

• A. Endocardium
• B. Myocardium
• C. Epicardium
• D. Pericardial sac

Answer: (B)

The heart wall has three layers, and the muscular middle layer is the myocardium, made of cardiac muscle that contracts to pump blood with each beat. This layer does the work of the heart, and electrical impulses coordinate the timing and strength of those contractions within it. The inner lining is the endocardium, the outer surface is the epicardium, and the pericardial sac is the protective outer covering that surrounds the heart. In rhythm problems, the electrical activity travels through the myocardium to produce coordinated heartbeat. So the muscular middle layer is the myocardium.

The heart wall has three layers, and the muscular middle layer is the myocardium, made of cardiac muscle that contracts to pump blood with each beat. This layer does the work of the heart, and electrical impulses coordinate the timing and strength of those contractions within it. The inner lining is the endocardium, the outer surface is the epicardium, and the pericardial sac is the protective outer covering that surrounds the heart. In rhythm problems, the electrical activity travels through the myocardium to produce coordinated heartbeat. So the muscular middle layer is the myocardium.