What are the three layers of the heart?

The correct answer outlines the three main layers of the heart, which are integral to its structure and function.

The endocardium is the innermost layer, lining the chambers of the heart and covering the heart valves. Its smooth surface plays a critical role in ensuring efficient blood flow and preventing turbulence that could lead to clot formation or damage.

The myocardium is the thick muscular layer of the heart responsible for contracting and pumping blood throughout the body. This layer comprises cardiac muscle tissue, and its strength and health directly influence the heart's ability to function effectively.

Lastly, the pericardium is a protective sac surrounding the heart. It consists of an outer fibrous layer and an inner serous layer, which reduces friction between the heart and surrounding structures during its contractions.

In contrast, the other options include terms associated with different tissues or reproductive anatomy (like endometrium and myometrium), which are not relevant to the heart's structure. Subendocardium refers to a deeper area within the endocardium, while epicardium is a layer commonly associated with pericardium, as it is the same as the visceral layer of the serous pericardium. However, the standard layers of the heart are best described