oskar schultz

Heart Inside Pericardial Sac

There are two layers to the pericardium: the outer fibrous pericardium, which is the tough tissue that protects the heart and anchors it in place, and the inner serous pericardium, which further cushions the heart against trauma and lubricates the area between the muscle and tough fibrous pericardium, so that no friction is formed while the heart pumps blood.

Atlas and Text-Book of Topographic and Applied Anatomy. Oskar Schultz and George D. Stewart, 1905.