The main difference between the pericardium and the epicardium lies in their structure, location, and function relative to the heart.
Here's a breakdown:
| Feature | Pericardium | Epicardium |
|---|---|---|
| Definition | The outer layer that does not compose part of the heart. It surrounds the heart but is not part of its wall. | The outermost layer of the heart wall itself. |
| Location | Surrounds the heart, forming a sac. | Outer surface of the heart muscle (myocardium). |
| Relationship | Protects the heart and provides lubrication. | Sometimes referred to as the visceral pericardium. This means it is a layer of the pericardium that adheres directly to the heart. |
| Function | Houses fluid that reduces friction to the heart and protects it as it pumps. | Protects the heart. |
Essentially, the pericardium is the protective sac around the heart, whereas the epicardium is the outermost layer of the heart itself; in fact, the epicardium is also known as the visceral pericardium, highlighting it is one of the two layers of the pericardium, specifically the one in direct contact with the heart. The pericardial space between the layers of the pericardium contains fluid to reduce friction during heartbeats.
