Superior Mediastinum and Root of Neck LO 8

8. Describe the pericardium.

The pericardium is a sac that surrounds and protects the heart, and provides it with sufficient space to expand (during diastole). The pericardium consists of two layers: on outer, fibrous pericardium, and an inner, serous pericardium.

The fibrous pericardium is a tough layer of dense connective tissue, which anchors the pericardium to the diaphragm and surrounding structures. The fibrous pericardium is inflexible, and prevents the heart from overfilling during diastole.

The serous pericardium is a relatively delicate, contiguous sac, which nearly completely envelops the heart. The superficial portion of the serous pericardium which fuses to the fibrous pericardium is known as the parietal pericardium. The deep portion of the serous pericardium which fuses directly to the heart is known as the visceral serous pericardium (i.e. the epicardium). Between the parietal and visceral pericardial layers is a potential space, the pericardial space, which contains a small amount of pericardial fluid to reduce friction.