| Hamate bone | |
|---|---|
_01_palmar_view.png) Left hand anterior view (palmar view). Hamate bone shown in red. | |
 The left hamate bone | |
| Details | |
| Pronunciation | /ˈheɪmət/ |
| Articulations | Articulates with five bones: thelunate proximally thefourth andfifthmetacarpals distally thetriangular medially thecapitate laterally |
| Identifiers | |
| Latin | os hamatum |
| MeSH | D051225 |
| TA98 | A02.4.08.012 |
| TA2 | 1259 |
| FMA | 23730 |
| Anatomical terms of bone | |
Thehamate bone (fromLatinhamatus, "hooked"), orunciform bone (fromLatinuncus, "hook"), Latinos hamatum and occasionally abbreviated as justhamatum,[1][2][3] is a bone in the humanwrist readily distinguishable by its wedge shape and a hook-like process ("hamulus") projecting from itspalmar surface.
The hamate is an irregularly shapedcarpal bone found within thehand. The hamate is found within the distal row of carpal bones, and abuts themetacarpals of thelittle finger andring finger.[4]: 708–709
Adjacent to the hamate on the ulnar side, and slightly proximal and ulnar to it, is thepisiform bone. Adjacent on the radial side is thecapitate, and proximal is thelunate bone.[4]: 708–709
The hamate bone has six surfaces:
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Thehook of hamate (Latin:hamulus) is found at the proximal,ulnar side of the hamate bone. The hook is a curved, hook-like process that projects 1–2 mm distally and radially.[5] Theulnar nerve hooks around the hook of hamate as it crosses towards the medial side of hand.
The hook forms the ulnar border of thecarpal tunnel, and the radial border forGuyon's canal. Numerous structures attach to it, including ligamentsfrom the pisiform, the transverse carpal ligament, and the tendon offlexor carpi ulnaris.[5]
Its medial surface to theflexor digiti minimi brevis andopponens digiti minimi; its lateral side is grooved for the passage of theflexor tendons into the palm of the hand.
The ossification of the hamate starts between 1 and 12 months.[6] The hamate does not fully ossify until about the 15th year of life.[5]
The bone is also found in many other mammals, and ishomologous with the "fourth distal carpal" of reptiles and amphibians.
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The carpal bones function as a unit to provide a bony superstructure for thehand.[4]: 708
The hamate bone is the bone most commonlyfractured when agolfer hits the ground hard with agolf club on the downswing or a hockey player hits the ice with a slap shot. The fracture is usually ahairline fracture, commonly missed on normalX-rays. Symptoms are pain aggravated by gripping, tenderness over the hamate and symptoms of irritation of theulnar nerve. This is characterized by numbness and weakness of the fifth digit with partial involvement of the fourth digit as well, the "ulnar 1½ fingers".
The hook of hamate is particularly prone to fracture-related complications such as non-union due to its tenuous blood supply.[5]
It is also a common injury inbaseball players. Several professional baseball players have had the bone removed during the course of their careers.[7][8][9][10][11][12] This condition has been called "Wilson's Wrist".[13]
The calcification of the hamate bone is seen on X-rays during puberty and is sometimes used inorthodontics to determine if an adolescent patient is suitable fororthognathic intervention (i.e. before or at their growth spurt).[citation needed]
The etymology derives from the Latinhamatus "hooked," fromhamus which means "hook".
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This article incorporates text in thepublic domain frompage 227 of the 20th edition ofGray's Anatomy(1918)
