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The ulnar nerve may be damaged at a number of sites:
Lesions at the wrist are characterised by hypothenar wasting and paralysis of the intrinsic muscles of the hand and consequent clawing of the hand. There is weakness of finger abduction and there is loss of adduction of the thumb. There is loss of sensation over the ulnar one and a half fingers.
The clawing of the hand is less marked with a high lesion because the ulnar half of flexor digitorum profundus is paralysed and so the terminal interphalangeal joints are not flexed. In other respects the motor and sensory losses are the same as a low lesion.