The pericardium is a fibroserous conical sac structure encompassing the heart and roots of the great cardiac vessels. In humans, it is located within the mediastinal cavity posterior to the sternum and cartilages of the third, fourth, fifth, sixth, and seventh ribs of the left thorax and is separated from the anterior wall of the thorax. It is encompassed from the posterior resting against the bronchi, the esophagus, the descending thoracic aorta, and the posterior regions of the mediastinal surface of each lung. Laterally, the pericardium is covered by the pleurae and lies along the mediastinal surfaces of the lung. It can come in direct contact with the chest wall near the ventricular apical region, but varies with the dimensions of the long axes of the heart or with various disease states. Under normal circumstances, the pericardium separates and isolates the heart from contact of the surrounding tissues, allowing freedom of cardiac movement within the confines of the pericardial space (Fig. 1).