Epicardium:The innermost layer of the pericardium, which is a cone-shaped sac made of fibrous tissue, envelops the heart and the origins of the major blood vessels. The pericardium consists of an outer and an inner layer. The outer layer is robust and thick, loosely covering the heart, and is connected to the central diaphragm and the back of the sternum (breastbone). The inner layer has two parts: one adheres closely to the heart, while the other lines the inside of the outer layer. The space between them contains a small amount of fluid, known as pericardial fluid, which serves as a lubricant to facilitate the heart's normal movement within the chest. The term "pericardium" translates to "around the heart." The outer layer of the pericardium is referred to as the fibrous pericardium, whereas the inner layer, which tightly encases the heart, is known as the epicardium or visceral pericardium.