Question

Thickest layer in heart is:

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

Hint:

The myocardium is the thickest layer of the heart and is essential for its pumping function.

Answer 1

The Correct Option is D

The heart wall consists of the thin outer epicardium, the thin inner endocardium, and the thick middle myocardium, which is made of cardiac muscle tissue responsible for the heart's pumping contractions. Because generating enough force to circulate blood throughout the body requires substantial muscle mass, the myocardium is by far the thickest of the three layers, while the pericardium is a separate protective sac outside the heart wall altogether.

Therefore, the correct answer is Myocardium.

Answer 2

Another way to work through this is to think about the function each layer serves and what that implies about how much tissue it needs.

1. Epicardium: Serving mainly a protective and lubricating function, this layer does not need to be thick.
2. Endocardium: Serving as a smooth lining to reduce friction with flowing blood, this layer only needs to be a thin cellular sheet.
3. Pericardium: Functioning as an external protective sac rather than part of the wall structure, it is not counted among the heart wall's three layers at all.
4. Myocardium: Serving as the contractile engine of the heart, generating the pressure needed to push blood through the circulatory system, this layer requires substantial muscular bulk, making it the thickest.

Since pumping blood requires the greatest mechanical work, the muscular layer responsible for that work is necessarily the thickest.

Therefore, the correct answer is Myocardium.