The superficial extensors of the forearm are the brachioradialis, extensor carpi radialis longus, anconeus, extensor carpi radialis brevis, extensor carpi ulnaris, extensor digitorum and extensor digiti minimi.
The extrinsic hand muscles originate in the forearm and insert on structures within the hand. They control movements of the wrist, hand, fingers and thumb.
“Tennis elbow” or lateral epicondylitis, is an injury to the extensor tendons that attach to the lateral epicondyle of the humerus. Most commonly it is the tendon of the extensor carpi radialis brevis muscle that is weakened or torn from injury or overuse.