Metacarpal Bones (Ossa Metacarpalia)

Metacarpal bones are situated in between the wrist and phalanges. All the metacarpals have enlarged and mostly irregular base (basis metacarpalis) at the proximal end and the rounded heads (caput metacarpale) at the distal end. The mobility of the 1^st and 5^th metacarpal bone is relatively high as they are involved in the opposition–reposition motion.

Bones of the hand. The palmar view — Metacarpal bones in situ. The palmar view.

Some specific features of the 1^st, 3^rd, and 5^th metacarpal bone

Download JPG image — The 1^st metacarpal bone is much shorter and thicker when compared to other metacarpals. Another peculiarity is the saddle-shaped base (dotted line), articulating with a congruent articular surface on the trapezoid bone. This joint allows the first metacarpal bone rotation around the sagittal and frontal axes.

Download JPG image — The characteristic feature of the 3^rd metacarpal bone is the styloid process at the base of the bone. This peculiarity also allows identifying the side as the process is at the radial side from the midline. When you look on the dorsal surface, the spinous process is on the left side for the right hand and vice versa.

Download JPG image — The fifth metacarpal bone is usually thinner than other metacarpals (when comparing bones from the same hand). Like the 1^st metacarpal, the 5^th also has the saddle-shaped articular surface at the base (dotted line).

360° rotation of the hand bones

First published: 08/Oct/2020
Last update: 15/Jun/2022