What is the main function of the pericardium?

The primary function of the pericardium is indeed to protect the heart. This double-walled sac encases the heart and provides a protective barrier against potential infections and trauma. Additionally, the pericardium contains a lubricating fluid that reduces friction as the heart beats and moves within the thoracic cavity, facilitating smoother heart motion.

Protection is crucial as it helps safeguard the heart from surrounding structures and maintains its positioning within the chest. The other functions listed, such as producing heartbeats, circulating blood, and regulating heart rate, are carried out by the heart itself and surrounding systems, rather than by the pericardium. Thus, its protective role is central to maintaining the heart's structural integrity and function.