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 thr ough Frohse's arcade in the supinator m. is one of the classical expla nations advanced for epicondylalgia. The object of this study was to d efine 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 upp er limbs were dissected and three segments of the deep branch of the r adial n. were distinguished: segment I, from its origin to its entry i nto the supinator m.; segment II, corresponding to its passage through the supinator m.; and segment III, extending from its exit from the s upinator m. to the origin of the nn. to the lateral epicondylar mm. Th e lengths of these three segments were defined, as well as the level o f division of the radial n. in relation to the joint-line, the thickne ss 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 microsc opically for evidence of lesions. The results were as follows. Segment I: absence of any marked histologic lesions; segment II: marked fibro us thickening of the perineurium and the interstitial connective tissu e, replacing certain nerve fibers; segment III: persistence of moderat e interstitial fibrosis. These findings appeared constant in all the s pecimens examined. These results indicate that the deep branch of the radial n. is most affected during its passage through the supinator m. It therefore remains advisable to treat certain epicondylalgias by a procedure at this site, dividing not only Frohse's arcade but also, an d this is less often stated, the supinator m. throughout its length, i n view of the lesions observed in segment II.