Compression of the radial nerve in the angle of the elbow can manifest itself clinically as "epicondylosis" ("tennis elbow"). Operative findings and systematic necropsy studies point to four specific areas in which a compression of the radial nerve occurs: 1. Occasionally, firm connective tissue fibers running between the brachialis and brachioradialis extend over the radial nerve in the proximal part of the radial tunnel. 2. Blood vessels may cross the nerve in the angle of the elbow and cause compression. 3. The profundus branch of the nerve may be compressed by the tendon of the extensor carpi radialis brevis when the origin of the muscle is located far medially, and 4. by the tendon of the superficial part of the supinator (arcade of Frohse). These structures can lead to an entrapment neuropathy of the radial nerve, and thereby to an epicondylosis humeri radialis. In patients with clinical symptoms of "epicondylitis" feeling pain along the radial nerve upon application of pressure, the nerve should be exposed to that compressing structures may possibly be released operatively.