The pericardium is a fibro-serous sac that contains the heart and the roots of the great vessels (Gray, 1918). In front it is separated from the anterior wall of the thorax for the most part, but a small area corresponding with the left half of the lower portion of the body of the sternum and the medial ends of the cartilages of the fourth and fifth ribs on the left side, comes in contact with the chest wall. In childhood, the lower extremity of the thymus is in contact with the front upper part of the pericardium. Posteriorly, the pericardium rests on the bronchi, esophagus, descending thoracic aorta, and the posterior part of the mediastinal surface of each lung. Laterally it is covered by the pleurae in relation with the mediastinal surfaces of the lung. The pericardium derives its arteries from the internal mammary and its musculophrenic branch, and from the descending thoracic aorta. Its nerve supply is derived from the vagus and phrenic nerves, and the sympathetic trunks.
The pericardium consists of two sacs intimately connected with each other, but different in structure (Gray, 1918). The outer sac is known as the fibrous pericardium, and consists of fibrous tissue. It forms a flask-shaped bag, whose neck is closed by fusion with the external coats of the great vessels, and is continuous with the pretracheal layer of the deep cervical fascia. Its base is attached to the central tendon and muscular fibers of the left side of the diaphragm. It is attached to the posterior surface of the sternum by the superior and inferior sternopericardiac ligaments. Fibrous prolongations from the fibrous pericardium cover the aorta, the superior vena cava, the right and left pulmonary arteries, and the four pulmonary veins. The inferior vena cava enters the pericardium through the central tendon, and is not covered by extensions of the fibrous pericardium.
The inner sac is known as the serous pericardium, and is a deli...