The Accessory Nerve (Cranial Nerve XI)

The eleventh cranial nerve is the accessory nerve. It is a motor nerve, responsible for innervating the sternocleidomastoid (SCM) and the trapezius muscles. The SCM is a muscle in the neck that allows rotation (looking side to side) and flexion (looking down) of the neck[1]. The trapezius muscle acts to shrug the shoulder.


  1. Opens in new window
  2. "Spinal Accessory Nerve". Structure of the Human body, Loyola University Medical Education Network. Archived from the original on 16 June 2007. Retrieved 2007-06-17.