Innervation of the extensor carpi radialis brevis and supinator muscles: Levels of origin and penetration of these muscular branches from the posterior interosseous nerve.

Dissections of 30 upper extremities from 15 skeletally mature cadavers were performed to identify the levels of origin and penetration of the innervation of the extensor carpi radialis brevis and supinator muscles. The humeroradial joint was used as a reference point for measurements. The most common pattern of extensor carpi radialis brevis innervation consisted of a single origin from the posterior interosseous nerve at the level of the humeroradial joint branching to penetrate the muscle at a level 30 mm to 60 mm distal to the humeroradial joint.