Anatomy of the radial nerve motor branches in the forearm

Knowledge of radial nerve motor branch anatomy is important when performing surgery in its vicinity, neurorrhaphy, and nerve blocks and for understanding the rate and order of recovery of muscle function after injury. Twenty normal fresh cadaver arms were dissected to quantitate radial nerve motor branch anatomy in the forearm. Though variable in individual specimens, innervation order from proximal to distal (based on mean shortest branch lengths) was brachioradialis, extensor carpi radialis longus, supinator, extensor carpi radialis brevis, extensor digitorum communis, extensor carpi ulnaris, extensor digiti quinti, abductor policis longus, extensor policis longus, extensor policis brevis, and extensor indicis proprius. In 10 specimens, branches innervated the brachialis. Mean distances from a point 100 mm proximal to the lateral epicondyle to the muscle measured along the shortest nerve branch ranged from 97.2 mm for the brachioradialis to 299.8 mm for the EIP. The mean number of muscular branches ranged from 1.1 in the EIP to 4.6 in the EDC. Mean nerve length from the radial styloid to the last motor branch was 115.8 mm.