The spinal accessory nerve originates in the brain and enables motion in the trapezius and sternomastoid muscles in the neck. A spinal accessory nerve injury can be caused by trauma or damage during surgery, resulting in shoulder pain, "winging" of the shoulder blades and weakness of the trapezius muscle.

What is the function of the spinal accessory nerve?

An unusual nerve that contains both cranial and spinal roots

The accessory nerve provides motor function (movement) to two muscles essential to neck and shoulder movement, the sternocleidomastoid (SCM) and the trapezius, as well as to the larynx (voice box) and other structures in the throat.

Where is the spinal accessory nerve located?

spinal accessory nerve can be identified entering the deep surface of the sternocleidomastoid muscle 4 cm or more below the mastoid process. it can be located at Erb's point just superior to where the greater auricular nerve surfaces from the deep neck.