Fifth metacarpal bone Fifth metacarpal bone The fifth metacarpal bone (metacarpal bone of the little finger or pinky finger) is the most medial and second-shortest of the metacarpal bones. It presents on its base one facet on its superior surface, which is concavo-convex and articulates with the hamate, and one on its radial side, which articulates with the fourth metacarpal. On its ulnar side is a prominent tubercle for the insertion of the tendon of the extensor carpi ulnaris muscle. The dorsal surface of the body is divided by an oblique ridge, which extends from near the ulnar side of the base to
Trapezium (bone) tubercle found on the anterior surface of the bone. It is where sometimes abductor pollicis brevis muscle attaches. The carpal bones function as a unit to provide a bony superstructure for the hand. The trapezium is the most radial of the bones surrounding the carpal tunnel. It is important in thumb movement. The trapezium is susceptible to arthritis at the joint with the metacarpal bone of the thumb, due to overuse. The etymology derives from the Greek "trapezion" which means "a little table", from "trapeza" meaning "table", itself from "(te)tra-" "four" and "pod-" "foot". The bone was first documented in