pericardiumthe

The pericardium is a double-layered sac that surrounds the heart and the roots of the great vessels. The outer layer, the fibrous pericardium, is a tough, inelastic sac made of dense connective tissue. It anchors the heart to surrounding structures like the diaphragm and the sternum, preventing overfilling and maintaining its position within the chest. The inner layer, the serous pericardium, is a delicate membrane that folds back on itself. It consists of two sub-layers: the parietal layer, which lines the fibrous pericardium, and the visceral layer, also known as the epicardium, which is directly attached to the heart's surface.

Between the parietal and visceral layers of the serous pericardium is a potential space called the pericardial cavity. This cavity contains a small amount of pericardial fluid, typically about 15-50 ml. This fluid acts as a lubricant, allowing the heart to beat smoothly and frictionless within the pericardial sac during each cardiac cycle. The pericardium protects the heart from infection and excessive stretching, and it plays a role in the heart's mechanics by providing a boundary. Inflammation of the pericardium is known as pericarditis, which can cause chest pain and other symptoms. Conditions affecting the pericardium can impact the heart's ability to pump effectively.