Metacarpus

Metacarpal bones
Metacarpals shown in red. Left hand, anterior (palmar) view.
The five metacarpal bones, numbered. Left hand, anterior (palmar) view.
Details
Origins	Carpal bones of wrist
Insertions	Proximal phalanges
Articulations	Carpometacarpal, intermetacarpal, metacarpophalangeal
Identifiers
Latin	ossa metacarpalia
MeSH	A01.378.800.667.572
TA	A02.4.09.001 A01.1.00.027
FMA	71336
Anatomical terms of bone []

In human anatomy, the metacarpal bones or metacarpus, form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist which forms the connection to the forearm. The metacarpal bones are equivalent to the metatarsal bones in the foot.

The metacarpals form a transverse arch to which the rigid row of distal carpal bones are fixed. The peripheral metacarpals (those of the thumb and little finger) form the sides of the cup of the palmar gutter and as they are brought together they deepen this concavity. The index metacarpal is the most firmly fixed, while the thumb metacarpal articulates with the trapezium and acts independently from the others. The middle metacarpals are tightly united to the carpus by intrinsic interlocking bone elements at their bases. The ring metacarpal forms a transitional element of the semi-independent last metacarpal.

Each metacarpal bone consists of a body and two extremities (head and base).

The body; shaft) is prismoid in form, and curved, so as to be convex in the longitudinal direction behind, concave in front. It presents three surfaces: medial, lateral, and dorsal.

The base or carpal extremity (basis) is of a cuboidal form, and broader behind than in front: it articulates with the carpal bones, and with the adjoining metacarpal bones; its dorsal and volar surfaces are rough, for the attachment of ligaments.

The head or digital extremity (caput) or neck per ICD-9 coding presents an oblong surface markedly convex from before backward, less so transversely, and flattened from side to side; it articulates with the proximal phalanx. It is broader, and extends farther upward, on the volar than on the dorsal aspect, and is longer in the antero-posterior than in the transverse diameter. On either side of the head is a tubercle for the attachment of the collateral ligament of the metacarpophalangeal joint.

The dorsal surface, broad and flat, supports the tendons of the extensor muscles.