What is the name of the most superficial layer of the heart made up of simple squamous epithelial tissue?

The superficial layer of the heart that is composed of simple squamous epithelial tissue is known as the epicardium. This layer serves as the outermost layer of the heart wall and is often found fused with the visceral layer of the pericardium, which forms part of the protective sac surrounding the heart. The simple squamous epithelium allows for smooth movement of the heart against surrounding tissues during the cardiac cycle.

In contrast, the myocardium is the thick muscular layer responsible for the contracting function of the heart. The endocardium lines the interior cavities of the heart and is also made of endothelial cells, but it is deeper than the epicardium. The pericardium, while surrounding and protecting the heart, is not a layer of the heart itself but rather a fibrous sac that contains the heart and the roots of the great vessels. Therefore, the description of the most superficial layer made of simple squamous epithelial tissue aligns perfectly with the definition of the epicardium.