Fourth_metacarpal_bone
The fourth metacarpal bone (metacarpal bone of the ring finger) is shorter and smaller than the third.
The base is small and quadrilateral; its superior surface presents two facets, a large one medially for articulation with the hamate, and a small one laterally for the capitate.
On the radial side are two oval facets, for articulation with the third metacarpal; and on the ulnar side a single concave facet, for the fifth metacarpal.