Intradural anastomoses between the accessory nerve and the posterior rootsof cervical nerves: Their clinical significance

This study was performed to identify the anastomoses between the accessory nerve and die posterior roots of cervical nerves below the level of C1 segm ent, and to evaluate their clinical significance. One hundred spinal cord s ides of Koreans were studied under the surgical microscope. In order to tra ce the posterior root of a cervical nerve after anastomosis with the access ory nerve, or the bridging fibers between the accessory nerve and the cervi cal posterior roots, the accessory nerves with the posterior roots and the bridging fibers were stained with osmium tetroxide. The anastomosis was cla ssified into five types, according to whether the accessory nerve and the c ervical posterior root crossed each other, and also according to the site o f the bridging fiber between them. The bridging fibers in the most common t ype of anastomoses were observed to connect the posterior roots of a cervic al nerve with the spinal rootlet of the accessory nerve. The possibility th at the motor fibers of accessory nerve from the, spinal cord may innervate the trapezius muscle through the cervical nerve, was discussed. (C) 2001 Wi ley-Liss, Inc.