The lungs are located in the chest on either side of the heart in the rib cage. They are conical in shape with a narrow rounded apex at the top and a broad base that rests on the diaphragm. The apex of the lung extends into the root of the neck, reaching shortly above the level of the sternal end of the first rib. The lungs stretch from close to the backbone in the rib cage to the front of the chest and downwards from the lower part of the trachea to the diaphragm. The left lung shares space with the heart, with an impression in its medial surface called the cardiac impression. The front and outer sides of the lung face the ribs, which make light indendations on their surfaces. The bottom of the lungs is smooth and rests on the diaphragm, matching its concavity. The medial surface of the lungs faces towards the centre of the chest, and lies against the heart, great vessels, and the carina where the two main bronchi branch off from the base of the trachea.
Both lungs have a central recession called the hilum at the root of the lung, where the blood vessels and airways pass into the lungs. There are also bronchopulmonary lymph nodes on the hilum.
The lungs are surrounded by the pulmonary pleurae. The pleurae are two serous membranes; the outer parietal pleura lines the inner wall of the rib cage and the inner visceral pleura directly lines the surface of the lungs. Between the pleurae is a potential space called the pleural cavity containing pleural fluid. Each lung is divided into lobes by the invaginations of the pleura as fissures. The fissures are double folds of pleura that section the lungs and help in their expansion.
The lobes of the lungs are further divided into bronchopulmonary segments based on the locations of bronchioles. Segments for the left and right lung are shown in the table. The segmental anatomy is useful clinically for localising disease processes in the lungs.