The Fibrous Pericardium is the outer layer of the pericardial sac. Fibrous connective tissue bands connect the fibrous pericardium to the sternum and the diaphragm.

The Serous Pericardium is composed of an outer parietal layer fused to the fibrous pericardium and an inner visceral layer (epicardium) adhered to the myocardium. The pericardial space between these two serous layers contains a thin film of fluid.