Human Anatomy - Kotsan I. Y. 2009

Skeleton of the upper limb
Metacarpal bones

The metacarpus consists of five short tubular bones. They are numbered sequentially from the thumb (I) to the little finger (V) of the hand. The first metacarpal bone is shorter than the others, yet more massive. The second metacarpal is the longest, while the subsequent bones gradually decrease in length toward the fifth metacarpal.

Each metacarpal bone comprises a body (corpus metacarpale), a base (basis metacarpalis), and a HEAD (caput metacarpale).

The body of each metacarpal bone is roughly triangular in shape and presents three surfaces: a dorsal (or posterior) surface, a lateral (or radial) surface, and a medial (or ulnar) surface.

The Base of the metacarpal bone is located proximally. The lateral surfaces of the bases feature articular facets through which adjacent bones articulate with one another. A styloid process (processus styloideus) projects proximally from the radial side of the base of the third metacarpal. The proximal surfaces of the bases of the second through fifth metacarpals bear flat articular facets for articulation with the distal row of Carpal Bones. The articular surface of the base of the first metacarpal is saddle-shaped, whereas in the fifth metacarpal it is divided into two parts by a small notch.

The metacarpal heads are situated distally and terminate in rounded articular surfaces for articulation with the proximal Phalanges of the digits. The head of the first metacarpal is slightly smaller than those of the remaining metacarpals.

Because the proximal and distal ends of each metacarpal bone are thickened, interosseous spaces of the metacarpus (spatia interossea metacarpi) remain between their shafts when the bones articulate, which lodge the interosseous Muscles.



Last update: 08/08/2026

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