Hamate - Os hamatum
The hamate bone (unciform bone) may be readily distinguished by its wedge-shaped form, and the hook-like process which projects from its volar surface. It is situated at the medial and lower angle of the carpus, with its base downward, resting on the fourth and fifth metacarpal bones, and its apex directed upward and lateralward.
The superior surface, the apex of the wedge, is narrow, convex, smooth, and articulates with the lunate.
The inferior surface articulates with the fourth and fifth metacarpal bones, by concave facets which are separated by a ridge.
The dorsal surface is triangular and rough for ligamentous attachment.
The volar surface presents, at its lower and ulnar side, a curved, hook-like process, the hamulus, directed forward and lateralward. This process gives attachment, by its apex, to the transverse carpal ligament and the Flexor carpi ulnaris; by its medial surface to the Flexor brevis and Opponens digiti quinti; its lateral side is grooved for the passage of the Flexor tendons into the palm of the hand. It is one of the four eminences on the front of the carpus to which the transverse carpal ligament of the wrist is attached; the others being the pisiform medially, the oblique ridge of the trapezium and the tubercle of the scaphoid laterally.
The medial surface articulates with thetriquetrum by an oblong facet, cut obliquely from above, downward and medialward.
The lateral surface articulates with the capitate by its upper and posterior part, the remaining portion being rough, for the attachment of ligaments.
The hamate articulates with five bones: the lunate proximally, the fourth and fifth metacarpals distally, the triquetrum medially, the capitate laterally.
This definition incorporates text from a public domain edition of Gray's Anatomy (20th U.S. edition of Gray's Anatomy of the Human Body, published in 1918 – from http://www.bartleby.com/107/).
General Anatomy > Bones; Skeletal system > Appendicular skeleton > Bones of upper limb > Free part of upper limb > Bones of hand > Carpal bones > Hamate