What does epicardium mean?
The epicardium is a thin, glistening serous membrane that forms the innermost layer of the pericardium, the protective sac surrounding the heart. Anatomists describe it as the visceral layer of the serous pericardium because it adheres closely to the heart's external surface, while the parietal layer lines the outer wall of the sac. Between these two layers lies a small volume of lubricating fluid that allows the beating heart to move with minimal friction. The term derives from Greek roots meaning "upon" and "heart," reflecting the membrane's position directly on the cardiac surface. Epicardium appears almost exclusively in medical, anatomical, and cardiological contexts, where clinicians also speak of epicardial arteries, epicardial fat, or the epicardial surface. Understanding this word helps distinguish the heart's outer covering from the endocardium, which instead lines the heart's internal chambers. It is a precise, formal term with no figurative use.
nounThe epicardium is the inner layer of the serous pericardium, a thin membrane that covers the outer surface of the heart. It is also known as the visceral layer of the serous pericardium.
- The thin serous membrane forming the inner layer of the pericardium and covering the external surface of the heart; the visceral layer of the serous pericardium.
- In pathology and cardiology contexts, the anatomical region or surface of the heart referred to in terms such as epicardial arteries or epicardial fat.
"The surgeon carefully sutured the graft to the epicardium during the bypass procedure."
"A small amount of fluid normally lubricates the space between the epicardium and the parietal pericardium."
"Coronary vessels run across the epicardium before branching into deeper myocardial tissue."
Rarely used in the plural, since each heart has a single epicardium; plural forms appear mainly in comparative or pathological descriptions involving multiple specimens or species.
"Histological sections of both hearts showed thickened epicardia consistent with chronic inflammation."
Your heart wears two coats — and the one touching it directly, the epicardium, shares a name with the Greek word for 'upon' plus 'heart.'
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of epicardium
Epicardium comes from the New Latin combining form built on the Greek prefix epi- (ἐπί), meaning "on" or "upon," and kardia (καρδία), meaning "heart." It was coined in the tradition of anatomical Latin alongside related terms such as pericardium, myocardium, and endocardium, which together describe the membranes and muscular tissue of the heart. Cognates sharing the root kardia include English borrowings such as cardiac, cardiologist, and pericarditis.
Related word forms
How epicardium is actually used
Epicardium is a technical term used almost exclusively in anatomy, medicine, cardiology, and related sciences. In everyday speech it is rarely encountered outside clinical or educational settings. Its adjective form, 'epicardial,' is more common in clinical literature (e.g., 'epicardial fat').
Easily confused with epicardium
The pericardium is the entire fibrous sac surrounding the heart, of which the epicardium is just one (innermost) layer.
The endocardium lines the inner chambers of the heart, whereas the epicardium covers its outer surface.