Guide the patient to pronate. With the patient relaxed, place the flat hand across the posterior proximal forearm. Remind the patient, if needed, to keep the fingers and thumb relaxed. Guide the patient to extend the wrist. The extensor carpi radialis brevis muscle should be the most prominently contracting muscle. Palpate other wrist extensor muscles to verify the palpation. From medial to lateral on the posterior proximal forearm, palpate the extensor carpi ulnaris with wrist extension and ulnar deviation motion, then the extensor digitorum communis with metacarpophalangeal extension of the four fingers, then the extensor carpi radialis brevis with pure wrist extension, fingers relaxed. This sequence is viewed on the right video clip after palpation of the extensor carpi radialis brevis muscle alone. With unclear muscle activity, increase the contraction of the extensor carpi radialis brevis by asking the patient to hold the wrist in extension while you provide a push on the hand in the direction of flexion.