metacarpal

Metacarpal bones are the five long bones of the palm, extending from the distal row of carpal bones to the proximal phalanges of the fingers. They form the framework of the midhand and contribute to grip and finger motion.

Each metacarpal has a base at the proximal end that articulates with carpal bones and neighboring metacarpals at the carpometacarpal joints, a shaft, and a head at the distal end that articulates with the proximal phalanx to form the metacarpophalangeal joint. The first metacarpal (thumb) has a saddle-type carpometacarpal joint permitting greater range of motion; the remaining metacarpals engage in gliding carpometacarpal articulations.

Five metacarpals are numbered I to V from the thumb to the little finger. The heads form the knuckles, while the bases participate in carpal articulation.

Function: They provide the palm’s framework for load transfer, grip, and finger movement, support the transverse and longitudinal arches of the hand, and enable opposition of the thumb.

Clinical notes: Metacarpal fractures are common injuries. Fractures typically involve the neck of the metacarpals, especially the fifth (boxer’s fracture). Treatment ranges from immobilization to surgical fixation to restore alignment and hand function.