Lung AnatomyThe lungs are located within the thoracic cavity just behind the ribs. They are bordered below by the diaphragm muscle and above by the shoulders. A two-layered sac called the pleural sac encloses each lung. The two layers adhere to the lung and the inside of the rib cage and are lubricated by a pleural fluid. The lungs are attached to the trachea, to bring oxygen in; and to the heart, which pumps oxygenated blood to the rest of the body. The lungs receive deoxygenated blood from the heart via the pulmonary arteries, and they send oxygenated blood back to the heart by the pulmonary veins. Bronchial vessels send oxygenated blood to the lungs in order to support their normal function. Lungs are divided into lobes, three lobes for the right lung and two lobes for the smaller left lung.