A person with an injury is not able to extend fingers but able to extend the wrist. The nerve which is injured: (A) Radial nerve, (B) Ulnar nerve, (C) Median nerve, (D) Posterior interosseous nerve
Answer is D. Posterior lnlerosseous Nerve It is marked by joining the following three points. A point 1 cm lateral to the biceps brachii tendon just below the level of the lateral epicondyle . The second point at the junction of the uPPer one third and lower two-thirds of a line joining themiddle of the posterior aspect of the head of the radius to the dorsal tubercle at the lower end of the radius or Lister's tubercle . The third point on the back of the wrist 1 cm medial to the dorsal tubercle. Posterior interosseous nerve supplies the muscles of posterior aspect of the forearm . Extension of wrist joint - .The main extensors are; Extensor carpi radialis longus. Extensor carpi radialis brevis. Extensor carpi ulnaris. It is assisted by the extensors of the fingers and thumb . Ref - bdc 6th edition 153,155