The anatomical relationship between the posterior interosseous nerve and the supinator muscle

Understanding the anatomical relationships in the region of the supinator m uscle is crucial in limiting surgical morbidity. The course, length, and mu scular innervations of the posterior interosseous nerve, as well as a detai led dissection of the supinator muscle, were described and recorded in 31 s pecimens from 16 adult cadavers. In our study, the radial nerve bifurcated into the posterior interosseous nerve and superficial radial nerve 8.0 +/- 1.9 cm distal to the lateral intermuscular septum. The bifurcation of the r adial nerve occurred 3.6 +/- 0.7 cm proximal to the leading edge of the sup inator, with the posterior interosseous nerve exiting the supinator muscle 3.8 +/- 0.9 cm distal to the proximal margin. The arcade of Frohse was memb ranous in 68% of our specimens and tendinous in 32%. The supinator had one semicircular head or layer in 71% of specimens and 2 distinct heads or laye rs, as defined by diverging muscle fibers, in 29%. With 2 heads, or layers, the superficial layer extended to the lateral epicondyle while the deep la yer extended to the ulna, below the radial notch. (J Hand Surg 2000;25A:936 -941. Copyright (C) 2000 by the American Society for Surgery of the Hand.).