is a double-walled sac that contains the heart
and the roots of the great vessels
There are two layers to the pericardial sac: the fibrous pericardium
and the 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
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.
The 10th century CE Islamic mystic Hallaj
described God as He "who flows between the pericardium and the heart, just as the tears flow from the eyelids."
- Schimmel, Annemarie (1975). Mystical Dimensions of Islam. Chapel Hill: University of North Carolina Press.
- - "Mediastinum: Pericardium (pericardial sac)"