ABSTRACT
The thorax, or chest, is a bony-cartilaginous cage containing and protecting the heart, the lungs, and their major blood vessels. The posterior surface (the back) is formed by the 12 thoracic vertebrae and posterior aspect of the ribs. The sides are formed by the ribs, separated from each other by the intercostal spaces, 11 in number, which are occupied by the intercostal muscles. The sternum and the ribs make up the front. The diaphragm forms the floor of the chest cavities and separates the thoracic from the abdominal cavities.
