Morphometric Investigations of the Connections between the Posterior C-1 Root and the Accessory Nerve in the Human Cranial Cervical Region

The anastomosis of the spinal section of the accessory nerve and the posterior C-1 root was examined in eight human corpses at the light-microscopical level by image analysis. The numbers of nerve fibers caudal and cranial to the anastomosis were compared. The morphometric data suggest that somatic efferent fibers of the spinal accessory nerve extend to proprioceptors in the sternocleido-mastoideus and trapezius muscles.