A client arrives for evaluation with the inability to extend her wrist, thumb, or MP joints of her right dominant hand. What nerve is involved?

A. Ulnar nerve
B. Radial nerve
C. Median nerve
D. Musculocutaneous nerve

ANS: B
This clinical picture is called the drop wrist and indicates radial nerve involvement. The radial nerve innervates the extensor-supinator group of muscles of the forearm, including the brachiora-dialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum communis, extensor digit minimi, extensor indicis, extensor carpi ulnaris, supinator, abductor pollicis longus, extensor pollicis brevis, and extensor pollicis longus.