What is the name of the tough membrane that surrounds the heart?

The correct answer is the pericardium, which is a tough, fibrous membrane that encases the heart. It serves several important functions, including protecting the heart from trauma, providing a barrier against infection, and anchoring the heart to surrounding structures. The pericardium also contains a small amount of fluid that allows the heart to move smoothly within the chest cavity as it beats.

The myocardium refers to the thick muscle layer of the heart itself, responsible for contracting and pumping blood. The endocardium is the inner lining of the heart chambers and valves, providing a smooth surface that reduces friction as blood flows through the heart. The epicardium is the outer layer of the heart wall, which is actually part of the pericardium. Each of these layers serves distinct roles in the functioning and protection of the heart, but it is the pericardium that specifically refers to the tough outer membrane that encases the heart itself.