Pericardium

The pericardium has a parietal and a visceral layer which form a double-layered sac in which the heart sits.

The parietal pericardium is the outer layer and is attached to mediastinal structures whilst the visceral pericardium is fused to the heart itself.

Between the layers lies a potential space known as the pericardial space which possesses a thin, lubricating film of pericardial fluid.

The parietal and serous layers fuse into one another in an irregular ring surrounding the great vessels.

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Parietal Pericardium

• The parietal pericardium is itself composed of two fused layers known as the fibrous pericardium and serous parietal pericardium. The Fibrous Pericardium is made of a tough, fibrous material and is attached to the central tendon of the diaphragm and the posterior surface of the sternum. The serous parietal pericardium is composed of a mesothelium, lines the internal surface of the parietal pericardium, and provides a lubricated surface upon which the visceral pericardium can move.
• The tough, unyielding nature of the fibrous pericardium means that the volume of the entire pericardial sac cannot increase beyond a certain amount which contributes to the pathogenesis of cardiac tamponade

Visceral Pericardium

• The visceral pericardium is composed of a mesothelium and forms the epicardium of the heart. This serous layer is highly lubricated and together with the serous parietal pericardium forms the frictionless dual-layered structure in which the heart pumps

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