Section IV. THE THORAX
The bony thorax (figure 2-23) is a cone-shaped cage formed by the sternum, the
costal cartilages, the 12 pairs of ribs, and the bodies of the 12 thoracic vertebrae. The
thorax contains and protects the heart, lungs, and great vessels. It serves for the
attachment of muscles and acts as a mechanical agent in the breathing process. The
shape and mobility of the ribs make possible the enlargement of the thoracic cavity
when they are elevated. The bony thorax, together with the intercostal muscles, plays
an important part in respiration.
Figure 2-23. Anterior aspects of the thoracic cage.