Clawing of 4th and 5th fingers and loss of normal extension of inter-phalangeal joint of the thumb when pinching together tips of thumb and index finger. Cause is ulnar nerve palsy leading to loss of adductor pollicus and deep head of flexor pollicis brevis. Sign is best elicited by having patient pinch piece of paper with thumb and index finger and having examiner try to withdraw it forcibly.