In anatomy, a sesamoid bone (/ˈsɛsəmɔɪd/) is a bone embedded within a tendon or a muscle. It is derived from the Latin word "sesamum" (sesame seed), due to the small size of most sesamoids. Often, these bones form in response to strain, or can be present as a normal variant. The kneecap is the largest sesamoid bone in the body. Sesamoids act like pulleys, providing a smooth surface for tendons to slide over, increasing the tendon's ability to transmit muscular forces.
The sesamoid is a small nodular bone most often present embedded in tendons in the region of the thumb. Calcification of sesamoid bone is one of the important features of pubertal growth spurt, which is earlier in females than in males. Absence of sesamoid bone indicates delay in reaching puberty.
Sesamoid bones can be found on joints throughout the body, including:
In equine anatomy, the term sesamoid bone usually refers to the two sesamoid bones found at the back of the fetlock or metacarpophalangeal/metatarsophalangeal joints in both hindlimbs and forelimbs. Strictly these should be termed the proxi...