Anatomical observations on the arcade of Frohse and other structures related to the deep radial nerve. Anatomical interpretation of deep radial nerve entrapment neuropathy.

In a series of 120 elbow regions (66 male, 54 female) from embalmed human cadavers, the authors observed the course of the deep radial nerve and then related it to structures such as a) the deep surface of the initial part of the extensor carpi radialis brevis, which was found to be tendinous in 90% of the cases, b) the superior hiatus of the supinator muscle, which formed a fibrous arcade of Frohse in 61% of the cases, and the distance of its peak from the lateral condyle, which ranged from 4 to 6 cm, and c) the angle between the superficial oblique muscle fibres of the supinator and the long axis of the radius, which varies from 18 degrees to 38 degrees and crossed the nerve almost transversely. The above anatomical factors--and particularly the thickened fibrous arcade of Frohse--are all important for the deep radial entrapment neuropathy in predisposed individuals.