Chest, also called thorax, is the part of the body between the base of the neck and the abdomen. Its sides are formed by the ribs, which are attached to the breastbone in front and to the spine in back. The diaphragm, a strong, dome-shaped muscle, forms the base of the chest. A thick, vertical partition called the mediastinum or mediastinal septum extends down the center of the thorax. Enclosed within this partition are the heart, the large blood vessels, the esophagus, the lower part of the trachea, and various glands and nerves. The lungs and their coverings are suspended on either side of the mediastinum. Mammals, birds, and crocodiles are the only animals that have a separate chest and abdomen. See also Diaphragm ; Heart ; Lung ; Respiration .
