Adduction of thumb. Injury to the Ulnar nerve Ulnar nerve is most commonly injured at the elbow, where it lies behind the medial epicondyle and at the wrist where it lies in front of flexor retinaculum. In high ulnar nerve injury at or proximal to elbow, all the muscles supplied by the ulnar nerve in the forearm and hand are paralyzed whereas in low ulnar nerve palsy, there is sparing of the forearm muscles (in flexor carpi ulnaris and flexor digitorum profundus). Sensory deficit are same in both high & low ulnar nerve injury.