The first metatarsal head demonstrates a biconvex articular surface with its articular cap expanding inferiorly over the plantar condyles to the level of the anatomic neck and dorsally about one third of that distance. The phalangeal base is correspondingly biconcave, and the capsular ligament inserts in close proximity with its articular outer edge. The compartment formed is reinforced by collateral ligaments (medial and lateral) and metatarsophalangeal ligaments (Fig. 16-21). The dorsal capsule is reinforced by the extensor hood expansion. The plantar plate (equivalent to the hand’s volar plates) is the fibrocartilaginous plantar metatarsophalangeal ligament and is continuous with the plantar aponeurosis, so that toe dorsiflexion tenses the plantar aponeurosis and stabilizes the foot’s longitudinal arch. The articular surface of the head of the first metatarsal presents with two fields in continuity: the superior phalangeal, which is convex, and the inferior sesamoidal, whose two sloped surfaces are grooved, and each corresponds to a sesamoid.183 The heads of the lesser metatarsals are convex or condylar (Fig. 16-11).