Hamate bone

The hamate is an irregularly shaped carpal bone found within the hand. The hamate is found within the distal row of carpal bones, and abuts the metacarpals of the little finger and ring finger.[4]^{: 708–709}

Adjacent to the hamate on the ulnar side, and slightly above it, is the pisiform bone. Adjacent on the radial side is the capitate, and proximal is the lunate bone.[4]^{: 708–709}

Hook

Hamate bone of the left hand. Hamulus shown in red.

The hook 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] The ulnar nerve hooks around the hook of hamate as it crosses towards the medial side of hand.

The hook forms the ulnar border of the carpal tunnel, and the radial border for Guyon's canal. Numerous structures attach to it, including ligaments from the pisiform, the transverse carpal ligament, and the tendon of Flexor carpi ulnaris.[5]

Its medial surface to the flexor digiti minimi brevis and opponens digiti minimi; its lateral side is grooved for the passage of the flexor tendons into the palm of the hand.

The carpal bones function as a unit to provide a bony superstructure for the hand.[4]^: 708

The hamate bone is the bone most commonly fractured when a golfer hits the ground hard with a golf club on the downswing or a hockey player hits the ice with a slap shot. The fracture is usually a hairline fracture, commonly missed on normal X-rays. Symptoms are pain aggravated by gripping, tenderness over the hamate and symptoms of irritation of the ulnar 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 in baseball 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 in orthodontics to determine if an adolescent patient is suitable for orthognathic intervention (i.e. before or at their growth spurt).

The etymology derives from the Latin hamatus "hooked," from hamus which means "hook".

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  Position of hamate bone (shown in red). Left hand. Animation.
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  Hamate bone of the left hand. The hook-like process is called hamulus.
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  Hamate bone.
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  Right hand anterior view (palmar view). Thumb on top.
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  Right hand posterior view (dorsal view). Thumb on bottom.
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  Bones of the left hand. Palmar surface. Hamate shown in yellow.
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  Bones of the left hand. Dorsal surface. Hamate shown in yellow.
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  Transverse section across the wrist and digits. Hamate shown in yellow.
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  Cross section of wrist (thumb on left). Hamate shown in red.
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  Right wrist joint. Deep dissection. Anterior (palmar) view.

Wikimedia Commons has media related to Hamate bone.

• Carpal bone
• Hypothenar hammer syndrome

This article incorporates text in the public domain from page 227 of the 20th edition of Gray's Anatomy (1918)