The mediastinum is the thoracic area between the 2 pleural cavities. The mediastinum contains vital structures of the circulatory, respiratory, digestive, and nervous systems including the heart and esophagus, and major thoracic vessels including the superior vena cava, inferior vena cava, pulmonary arteries, pulmonary veins, and aorta. The mediastinum extends from the upper thoracic aperture to the diaphragm and is bordered by the lungs.