The ulnar collateral ligament of the thumb runs along the ulnar side of the metacarpo-phalangeal joint of the thumb

Thumb

The thumb is the first digit of the hand. When a person is standing in the medical anatomical position , the thumb is the lateral-most digit...

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It is on the radial side of the wrist, but on the ulnar side of the thumb. It should not be confused with the ulnar collateral ligament of wrist joint.

Clinical significance

Injuries to it cause instability and loss of function of the thumb. Acutely this injury is known as the Skier's thumb or if the result of chronic injury Gamekeeper's thumb

Gamekeeper's thumb

Gamekeeper's thumb is a type of injury to the ulnar collateral ligament of the thumb. The UCL is torn at its insertion site into the proximal phalanx of the thumb in the vast majority of cases...

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