Emergency Medical Technician (EMT) Intermediate Practice Exam 2026 – 400 Free Practice Questions to Pass the Exam

The fibrous sac that surrounds the heart is called the pericardium. This structure consists of two layers: the fibrous pericardium, which is the outer layer that provides protection and prevents overexpansion of the heart, and the serous pericardium, which contains a fluid-filled space that reduces friction as the heart beats.

The pericardium plays a crucial role in providing stability to the heart within the thoracic cavity while allowing it the necessary mobility during contractions. It also serves as a barrier against infection from surrounding structures and helps to anchor the heart to the surrounding mediastinum.

In contrast, the peritoneum is the serous membrane that lines the abdominal cavity and covers the abdominal organs. The endocardium is the inner lining of the heart chambers and valves, whereas the myocardium is the muscular layer of the heart responsible for contraction. Understanding the function and location of these different layers and membranes is essential for recognizing their unique roles in cardiovascular health.