Topographic Anatomy of the Spinal Accessory Nerve in the Posterior Triangle Neck.

The spinal accessory nerve (SAN) represents a commonly used trunk in peripheral nerve surgery. During this procedure, the SAN is located within the posterior cervical triangle. Although its location may be assisted by a neurostimulator, the anatomical landmarks still play a key role in the identification of the SAN. 20 posterior cervical triangles of formalin fixed adult cadavers were studied. The distance between the mandibular angle and the acromioclavicular joint (M-AC), and the distance between the mandibular angle and the esternal end of the clavicle (M–C) were measured. The topography of the SAN within those lines both with the head in neutral position and rotated 30 degrees contralaterally was registered. The M-C was mean 158mm with neutral position, and 160mm with the head rotated 30 degrees. The SAN was located in the majority of the cases within the middle third of this line. The M-AC was mean 163mm with head in neutral position and 156mm with head rotation of 30 degrees. The SAN was located in every case within the middle third of this line. The results presented in this paper are of great importance for surgical location of the SAN within the posterior cervical triangle.