Bone · Hand

4th metacarpal

The most slender of the metacarpals, lying between the fixed index and middle rays and the mobile little-finger ray. Its base is small and carries facets for both the hamate and the capitate, so it straddles the boundary between the rigid and the mobile halves of the hand. Unlike its neighbours it receives no wrist tendon at its base at all; it is moved entirely by the small muscles packed between the metacarpals and by the long finger tendons crossing it.