Epicardium

The epicardium is the outer layer of the heart wall and is also known as the visceral layer. It consists of a thin layer of cells, which are separated from the myocardium by a layer of serous fluid. Its main function is to protect the underlying heart muscle from external trauma and to serve as a lubricating surface. It also plays an important role in the regulation of cardiac functions, including coronary blood flow, conduction of electrical impulses, and immunity. Its physiological significance is further enhanced by the presence of several important enzymes, hormones, and other molecules that support the heart's functions. The epicardium has a wide range of clinical uses including in coronary artery bypass surgery and as a source of stem cells for cardiac regenerative therapies.