Anatomic basis of the physiopathology of the epicondylalgias: a study of the deep branch of the radial nerve.

Compression of the deep branch of the radial n. during its passage through Fröhse's arcade in the supinator m. is one of the classical explanations advanced for epicondylalgia. The object of this study was to define the anatomy of the deep branch of the radial n. from its origin up to the origin of the branches to the lateral epicondylar mm. 34 upper limbs were dissected and three segments of the deep branch of the radial n. were distinguished: segment I, from its origin to its entry into the supinator m.; segment II, corresponding to its passage through the supinator m.; and segment III, extending from its exit from the supinator m. to the origin of the nn. to the lateral epicondylar mm. The lengths of these three segments were defined, as well as the level of division of the radial n. in relation to the joint-line, the thickness of the arcade of the supinator m., and the number of nerve branches to the supinator m. It was found that segment III is closely related to the radial head, around which it winds in supination and extension. The three nerve segments thus defined were studied separately microscopically for evidence of lesions. The results were as follows. Segment I: absence of any marked histologic lesions; segment II: marked fibrous thickening of the perineurium and the interstitial connective tissue, replacing certain nerve fibers; segment III: persistence of moderate interstitial fibrosis. These findings appeared constant in all the specimens examined. These results indicate that the deep branch of the radial n. is most affected during its passage through the supinator m.(ABSTRACT TRUNCATED AT 250 WORDS)