Hamate Bone

The hamate is a wedge-shaped, triangular-shaped most medial unciform bone that forms part of the distal carpal row, surrounded by three other carpal bones; the capitate, triquetrum, and lunate bones and articulating with the capitate (radially), triquetrum (proximally), and fifth and fourth metacarpals (distally) and hamate serve as an attachment point for three tendons (opponens digiti minimi, flexor digiti minimi brevis, abductor digiti minimi, and flexor carpi ulnaris) ligaments flexor retinaculum, pisohamate ligament, triquetrohamate ligament, capitohamate ligament.

Hamate Bone

Structure

The hamate is found within the distal row of carpal bones and about the metacarpals of the little finger and ring finger.

Adjacent to the hamate on the ulnar side is lightly above it, which is adjacent on the radial side is the capitate, and proximal is the lunate bone.

Surfaces

The hamate bone has six surfaces the body of the hamate has six surfaces: medial and lateral, proximal and distal, palmar, and dorsal.

  • The superior surface, the apex of the wedge, is narrow, convex, smooth, and articulates with the lunate bone.
  • The inferior surface by concave facets is separated by a ridge that articulates with the fourth and fifth metacarpal bones.
  • The dorsal surface is a triangular shape and rough for ligamentous attachment.
  • The palmar surface presents, at its lower and ulnar side, a curved, hook-like process, the hook-like osseous projection called the hamulus (or hook) of the hamate bone, directed forward,  laterally, and the hamulus curved with a lateral concavity and its tip inclines laterally serves as the attachment point for a number of different muscles and ligaments of the hand and forearm, including the flexor retinaculum.
  • The medial surface articulates with the triangular bone by an oblong facet, cut obliquely from above, downward and medialward.
  • The lateral surface is rough, and articulates with the capitate by its upper and posterior parts, for the attachment of ligaments.
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Hamate Bone

Hook

The hook of hamate (Latin: hamulus) is found at the proximal, ulnar side of the hamate bone contributes to the formation of the medial wall of the carpal tunnel and the lateral wall of the ulnar canal (i.e. Guyon’s canal). The hook is a curved, hook-like process that projects 1–2 mm distally, radially, forms the ulnar border of the carpal tunnel, and the radial border for Guyon’s canal. The ulnar nerve hooks around the hamate as it crosses towards the medial side of the hand.

The various structures are attached to it, including ligaments from the pisiform bone, the transverse carpal ligament, and the tendon for flexion of the hand the flexor carpi ulnaris. Its medial surface to the flexor digiti minimi brevis muscle and opponens digiti minimi muscle; its lateral side forms a grooved for the passage of the Flexor tendons into the palm of the hand.

References