What is the pericardium?

The pericardium is accurately described as a double-layered membrane surrounding the heart. This structure serves several important functions for the heart, including providing a protective barrier and reducing friction between the heart and surrounding tissues as the heart beats. The outer layer of the pericardium is known as the fibrous pericardium, which provides stability, while the inner layer, the serous pericardium, includes two sub-layers that produce pericardial fluid to lubricate the heart.

Understanding the significance of the pericardium is vital, as it plays a crucial role in cardiac health and function. Conditions like pericarditis, where inflammation occurs, can lead to complications affecting heart function. The other options do not reflect the correct anatomical structures related to the heart; for instance, the innermost layer of the heart refers to the endocardium, and the outer layer of heart valves pertains to other components entirely unrelated to the definition of the pericardium.