The sesamoids are small, round bones so named because they resemble sesame seeds (Fig. 16-11). The sesamoids are embedded, partially or totally, in the substance of a corresponding tendon juxtaposed to articulations and are anatomically a part of a gliding or pressure-absorbing mechanism. Structurally, some sesamoids always ossify, whereas others remain cartilaginous or fibrocartilaginous for life. The tibial (medial) and fibular (lateral) sesamoids of the flexor hallucis brevis are always present plantar to the first metatarsal head. Other locations where sesamoids may be found are in the plantar plates of the metatarsophalangeal and interphalangeal joints, the intrinsic tendons of the lesser toes, or in the tendons of the tibialis anterior, tibialis posterior, or peroneus longus.