MATERIAL and METHODS: 38 cadavers (76 accessory and 76 phrenic nerves) were dissected in the study. The width, length and thickness of each accessory nerve and phrenic nerve above clavicle were measured. The distances from several landmarks on accessory nerve to the origin and the end of the phrenic nerve above clavicle were measured too. Then, the number of motor nerve fibers on different sections of the nerves was calculated using the technique of immunohistochemistry.

RESULTS: The accessory nerves distal to its sternocleidomastoid muscular branches were 1.52±0.32mm ~1.54±0.29mm in width, 0.52± 0.18mm ~ 0.56±0.20mm in thickness and 9.52±0.98cm in length. And the phrenic nerves above clavicle were 1.44±0.23mm ~ 1.45±0.24mm in width, 0.47±0.15mm ~ 0.56±0.25mm in thickness and 6.48±0.78cm in length. The distance between the starting point of accessory nerve and phrenic nerve were 3.24±1.17cm, and the distance between the starting point of accessory nerve and the end of the phrenic nerve above clavicle were 8.72±0.84cm. The numbers of motor nerve fibers in accessory nerve were 1038±320~1102±216, before giving out the sternocleidomastoid muscular branches. The number of motor nerve fibers in the phrenic nerve was 911±321~1338±467.

CONCLUSION: The accessory nerve and the phrenic were similar in width, thickness and the number of motor nerve fibers. And the lengths of accessory nerve were long enough for neuritisation with phrenic nerve. Keywords : Phrenic nerve, Accessory nerve, Anatomy, Spinal cord injury, Reconstruction