Radial nerve entrapment at the elbow: surgical anatomy.

The surgical anatomy of interest in the posterior interosseous nerve syndrome was studied to shed light on the ramifying pattern of the radial nerve, the number of its muscular branches and their branching levels, and to pinpoint the location of the fibrous bands that may cause radial nerve entrapment. The fibrous arch of the supinator muscle (arcade of Frohse) was found to lie 3 cm to 5 cm below Hueter's line, that of the extensor carpi radialis brevis muscle lay 0.5 cm to 1 cm proximal to the arcade of Frohse. Symptom patterns in terms of muscle weakness caused by radial nerve entrapment at different levels were also evaluated.