Hamate

A.Prof Frank Gaillard and Dr Craig Hacking et al.

The hamate is one of the carpal bones, forms part of the distal carpal row and has a characteristic hook on its volar surface.

The hamate has a wedge-shaped body. It bears an uncinate (unciform) hamulus (hook of hamate) which projects in a volar fashion from the distal part of its palmar surface. It is the most ulnar based bone within the distal carpal row. It has four surfaces:

  • superior surface: apex of the wedge is narrow, convex, and smooth
  • inferior surface: concave facets separated by a ridge
  • volar surface: hook-like process (hamulus) on the lower and ulnar side
  • medial surface: oblong facet

The hamate articulates with five bones: the lunate, capitate, triquetral, fourth metacarpal, and fifth metacarpal:

  • proximal thin margin of the wedge articulates with the lunate while the fourth and fifth metacarpals articulate with the base distally
  • medial surface is broad and articulates with the triquetrum
  • lateral surface articulates with the capitate
  • hook of the hamate is distal and radial in relation to the pisiform

  • flexor retinaculum attaches to the apex of the hamulus
  • transverse carpal ligament
  • pisohamate ligament
  • triquetrohamate ligament
  • capitohamate ligament

Nearly 100% of hamate specimens have radial artery supply. Most specimens have dual radial and ulnar supply with the ulnar artery contributing a smaller percentage. ~30% have absent ulnar artery supply.

A terminal deep branch of the ulnar nerve lies in a transverse groove underneath the hook of the hamate towards its base. 

It is the second bone to ossify following the capitate. It is thought to start ossifying by the end of the third month. Fusion is complete by age 14-16. 

The term derives from the Latin Hamatus meaning hooked.

The hamate may be visualised on a number of series of the distal upper limb including:

Routine PA and lateral views of the wrist potentially miss hamate fractures. Carpal tunnel views, in addition to PA, lateral, and oblique views are typically required when hamate fractures are suspected.

CT has a sensitivity of 100% and a specificity of 94% in visualising fractures of the hamate compared to x-ray which has a sensitivity of 72% and specificity of 88%.4 

Upper limb anatomy
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Article information

rID: 41451
Section: Anatomy
Tag: cases
Synonyms or Alternate Spellings:
  • Hamate bone

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    Figure 1: carpal bones
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