The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the right. The clavicle is the only long bone in the body that lies horizontally. Together with the shoulder blade, it makes up the shoulder girdle.

Source: Wikipedia