Although, the accessory nerve is the 11th cranial nerve, we will discuss here the spinal component due to its importance in nerve injuries and repair. The spinal accessory nerve arises from the upper cervical spinal cord (C1–C5), ascends between the dentate ligament and the posterior cervical rootlets, then through the foramen magnum joins the cranial part, and exits through the jugular foramen. It runs through or deep to the sternocleidomastoid (SCM) muscle. It courses subcutaneously in the posterior triangle of the neck from the posterior border of the SCM cranially to the anterior border of the trapezius muscle caudally. It supplies both the SCM and the trapezius muscles.
KeywordsCervical Spinal Cord Anterior Border Trapezius Muscle Posterior Border Accessory Nerve
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