Connection types between the spinal root of the accessory nerve and the posterior roots of the C2–C6 spinal nerves

Purpose The aim of this study was to demonstrate the connection types and frequency between the accessory nerve and the posterior roots of the C2–C6 cervical nerves. Methods The cranial cervical regions of 49 specimens from 27 human cadavers were used for the present study under an operating microscope. Results Five different connection types between the accessory nerve and the posterior roots of the cervical nerves were recorded and photographed (types A–F). One of these types was not described previously in literature (type F). All connections between the posterior roots of the C2–C6 spinal nerves and the accessory nerve were at the level of the C2 segment. Type B was the most frequently seen type in our series. One of the rootlets of the cervical posterior root joined the accessory nerve without a connection to the spinal cord in type B. Conclusions The clinical importance of these connections is especially noticed during the radical neck dissection as it may lead to the development of the shoulder-arm syndrome.