Epicardium describes the outer layer of heart tissue (from Greek; epi- outer, cardium heart). When considered as a part of the pericardium, it is the inner layer, or visceral pericardium.

Its largest constituent is connective tissue and functions as a protective layer. The visceral pericardium apparently produces the pericardial fluid, which lubricates motion between the inner and outer layers of the pericardium.

Cardiovascular system - Heart	Edit (http://en.wikipedia.org/w/wiki.phtml?title=MediaWiki:Heart)
Pericardium - Epicardium - Myocardium - Endocardium - Purkinje fibers - Cardiac pacemaker - Sinoatrial node - Atrioventricular node - Heart valves