Claw hand, also known as ulnar claw or spinster's claw, is a deformity of the hand caused by damage to the ulnar nerve. This results in paralysis of muscles that normally allow the fingers to straighten. In a claw hand, the fingers are bent at the middle knuckle and straighten at the top knuckle, giving the hand a claw-like posture. Common causes include nerve damage, skin scarring, bacterial diseases like leprosy, and birth defects. Treatment may involve resting the hand, wearing a brace, medications for underlying conditions, surgery to repair nerves or muscles, and skin grafts for scarring.