Epicardium: The outermost layer, also known as the visceral layer of the serous pericardium. It is composed of mesothelial cells, connective tissue, and adipose tissue. Myocardium: The middle and thickest layer, primarily made up of cardiac muscle cells (cardiomyocytes). This layer is responsible for the contractile function of the heart. Endocardium: The innermost layer, which lines the interior of the heart chambers. It consists of endothelial cells and a thin layer of connective tissue.
