Conditions

A sesamoid bone is an actual bone that developed independantly from other bones as the body developed,unlike accessory bones which are seperations of ordinary bones during development. The sesmoid bones derived the term from "sesame seeds" due to the small, oval shape in appearance. A sesamoid bone is a consistent structure, meaning that when they form, they do so at the same position every time. The biggest example of a sesamoid bone is the knee cap. Sesamoids are generally embedded within capsules or tendons where they insert or sharply change directions. They are thought to protect excessive friction or change the direction of the pull of the tendons for efficiency. Some sesamoids are seen on x-ray as they are ossified, meaning that they have completely formed bone. Others are not seen as they remain to be cartilage and unossified. Common sesamoids of the foot are the tibial sesamoid and fibular sesamoid under the first metatarsal head. Sesamoiditis occurs when these sesamoids become injured and inflammed. The Os Peroneum is the sesamoid that occurs at the peroneus longus tendon groove on the cuboid.