Description
The base is the expanded proximal end of the proximal phalanx of thumb. It is the proximal continuation of its body and contains a proximal articular facet, which articulates with the distal articular facet of the first metacarpal bone, forming the first metacarpophalangeal joint.
The base of the proximal phalanx of thumb provides insertion sites for the:
—adductor pollicis muscle;
—flexor pollicis brevis muscle;
—extensor pollicis brevis muscle;
—abductor pollicis brevis muscle.
It also provides attachment sites for the collateral and palmar ligaments of the first metacarpophalangeal joint.
