What is a visceral pericardium?

Membrane: The visceral pericardium is a very thin membrane attached to the surface of the heart. The parietal pericardium is a thicker, tougher membrane that also surrounds the heart. When we refer to "the pericardium", we are mostly referring to the parietal pericardium. A very small amount of fluid usually exists in between these two layers. When the amount of fluid is called a pericardial effusion.

2 layers: The pericardium is the tough fibrous sac that encloses the heart. It is made up of 2 layers: the outer layer is called the parietal pericardium and the inner layer which is in contact with the outer heart muscle is the visceral pericardium. Under normal circumstances, there is no space between these 2 layers, just a "potential" space. Fluid can separate the layers in certain diseases.