The pericardium is a thin double-layered sac which encloses the heart. Fluid is contained within the layers and lubricates the constantly rubbing surfaces.
Review Date 4/30/2020
Updated by: Thomas S. Metkus, MD, Assistant Professor of Medicine and Surgery, Johns Hopkins University School of Medicine, Baltimore, MD. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.