The lungs are located within the chest cavity on either side of the heart. Each lung reaches from the collarbone to the border between the chest and abdominal cavities.
The diaphragm, the muscle that helps the lungs take in air, sits below the lungs on top of the abdominal cavity. The human lung is usually between 10 and 12 inches long. The left lung is slightly smaller than the right lung because the right lung contains three sections called lobes, whereas the left lung only has two lobes. The left lung must be smaller to accommodate the heart's position. Surrounding the lungs is the rib cage, which protects the lungs from damage.