What is the main function of the pericardium?

The main function of the pericardium is to protect the heart. This double-walled sac surrounds the heart and serves several important roles, including acting as a barrier against infection and inflammation, maintaining the heart's position within the thoracic cavity, and preventing over-expansion of the heart during vigorous activity by limiting its movement. The pericardial fluid within the cavity also reduces friction between the heart and surrounding structures as the heart beats.

Other functions listed, such as facilitating blood flow, regulating body temperature, and absorbing oxygen, are not directly associated with the pericardium. For example, facilitating blood flow is primarily the role of the heart and its surrounding blood vessels, while body temperature regulation is managed by the integumentary and circulatory systems. Oxygen absorption occurs in the lungs, not the pericardium.