AbstractCommon anatomical structures that can lead to radial nerve entrapment in the radial tunnel (radial tunnel syndrome) were studied in 46 embalmed cadaveric upper limbs. After dissecting the radial tunnel, we investigated: the radial nerve and its division into superficial and deep (DBRN) branches; the course of the DBRN in relation to the extensor carpi radialis brevis (ECRB) muscle; the presence of fat; fibrous adhesions between the anterior radiohumeral joint capsule and the DBRN; the nature of the superomedial margin of the ECRB; vascular arcades of the radial recurrent vessels; and the superior and inferior borders of the superficial layer of the supinator muscle. The locations of some of these structures were measured in reference to two fixed points: the radiohumeral joint line and a line joining the tips of medial and lateral epicondyles of humerus. Near the radiohumeral joint, fibrous adhesions were observed between the DBRN and underlying capsule in 23/46 (50%) cases; vascular arcades of the radial recurrent vessels were found in 33/46 (72%) cases; the superomedial margin of the ECRB was tendinous in 36/46 (78%) instances; the superior border of the superficial layer of the supinator muscle was noted to be tendinous (arcade of Frohse) in 40/46 (87%) specimens, and the inferior border of the superficial layer of the supinator muscle was tendinous in 30/46 (65%) cases. These anatomical features in the radial tunnel are significant enough to lead to entrapment neuropathy of the radial nerve. Anat. Clin. Anat. 17:21–25, 2004. © 2003 Wiley‐Liss, Inc.