The Human Suprascapular Nerve belongs to both Anterior and Posterior Divisions of the Brachial Plexus

For the sake of clarifying which division of the brachial plexus, anterior or posterior, does the human suprascapular nerve belong to, the suprascapular nerve and cervical nerves concerned were teased into bundles of fibers by the fiber analysis method in six adult human arms of cadavers. The suprascapular nerve received fibers from C4, C5 and C6 in two cases which have a communicating branch between C4 and C5, from C6 and C6 in three cases and only from C5 in one case. In contrast with the posterior root fibers, the anterior root fibers of C5 and C6 could easily be divided into anterior and posterior groups of bundles which entered the anterior and the posterior divisions of the brachial plexus and were called anterior motor and posterior motor elements respectively. The suprascapular nerve received fibers from the anterior and the posterior motor elements of C5 in all cases. In addition to the C5, the nerve received fibers from both elements of C6 in three cases or from the anterior element of C6 in two cases. From this result the suprascapular nerve is judged to be a nerve which belongs to both anterior and posterior divisions of the brachial plexus.