What are the two main layers of the pericardium?

The correct answer identifies the two main layers of the pericardium as the visceral and parietal layers. The pericardium is a double-walled sac that surrounds the heart, providing it with physical protection and anchoring it within the thoracic cavity. The visceral layer, also known as the epicardium, is the inner layer that closely adheres to the surface of the heart, while the parietal layer is the outer layer that provides a protective barrier.

The distinction between these layers is important for understanding their functions in cardiac protection and structure. The visceral layer facilitates the smooth movement of the heart against surrounding structures during contractions, while the parietal layer provides a sturdy outer shell.

The other options mention structures that do not describe the layers of the pericardium: the fibrous and serous refer to components of the pericardium but do not specifically identify the main layers; epicardium and myocardium reference layers related to the heart itself, with the myocardium being the muscular layer of the heart wall; and the endocardium is the inner lining of the heart chambers, which is unrelated to the pericardial structure.