Third metatarsophalangeal joint

The third metatarsophalangeal joint is a synovial condyloid joint formed by the articulation of the head of the third metatarsal and the base of the proximal phalanx of the third toe. The joint is stabilized by several key structures:

• Joint capsule: A fibrous capsule surrounds the joint, reinforced dorsally and plantarly. The dorsal capsule is thin, while the plantar aspect is thickened by the plantar plate.

• Plantar plate: This is a fibrocartilaginous structure anchored proximally to the metatarsal head (notch between the medial and lateral plantar condyles) and distally to the base of the proximal phalanx. It merges with the collateral ligaments and deep transverse metatarsal ligament, providing resistance to hyperextension and stabilizing the joint.

• Collateral ligaments: Medial and lateral collateral ligaments attach from the metatarsal head to the base of the proximal phalanx, blending with the plantar plate and contributing to mediolateral stability.

• Deep transverse metatarsal ligament: This ligament connects adjacent metatarsal heads and is closely associated with the plantar plate and collateral ligaments, further stabilizing the joint.

• Flexor tendons: The flexor digitorum longus and brevis tendons course plantar to the joint, separated from the joint capsule by the plantar plate, and assist in toe flexion.

• Dorsal structures: The extensor digitorum longus and brevis tendons pass dorsally over the joint, with the dorsal capsule providing minimal reinforcement.