Layers
Pericardium is a tough double layered membrane which covers the heart. The space between the two layers of it is filled with a pericardium fluid which protects the heart from any kind of external jerk or shock. There are two layers to the pericardial sac: the outermost fibrous pericardium and the inner serous pericardium. The serous pericardium, in turn, is divided into two layers, the parietal pericardium, which is fused to and inseparable from the fibrous pericardium, and the visceral pericardium, which is part of the epicardium. The epicardium is the layer immediately outside of the heart muscle proper (the myocardium).
The visceral layer extends to the beginning of the great vessels, becoming one with the parietal layer of the serous pericardium. This happens at two areas; where the aorta and pulmonary trunk leave the heart and where the superior vena cava, inferior vena cava and pulmonary veins enter the heart.
In between the parietal and visceral pericardial layers there is a potential space called the pericardial cavity. It is normally lubricated by a film of pericardial fluid. Too much fluid in the cavity (such as in a pericardial effusion) can result in pericardial tamponade (compression of the heart within the pericardial sac). A pericardectomy is sometimes needed in these cases.
Read more about this topic: Pericardium
Famous quotes containing the word layers:
“The force of a death should be enormous but how can you know what kind of man you’ve killed or who was the braver and stronger if you have to peer through layers of glass that deliver the image but obscure the meaning of the act? War has a conscience or it’s ordinary murder.”
—Don Delillo (b. 1926)
“I think it’s the real world. The people we’re writing about in professional sports, they’re suffering and living and dying and loving and trying to make their way through life just as the brick layers and politicians are.”
—Walter Wellesley (Red)