ACCESSORY NERVE ANATOMYWhile the accessory nerve does contain a few sensory elements, it is primarily a motor nerve. Proprioceptors directly from the muscles which it innervates provide some sensory fibers.
The accessory nerve has a dual origin, the only cranial nerve as such, and it begins both from the spinal cord and the brain.
ACCESSORY NERVE FUNCTIONSThe medulla oblongata contains the nuclei of its brain origination while the cranial root passes from there to the jugular foramen next to the vagus nerve. Here, it initiates the innervation of the soft palate, the larynx, and the pharynx. This allows for the reflexive action of swallowing.
The first five segments of the cervical segment of the spinal cord yield the origin of the spinal root. The spinal root joins the cranial root after passing through the foramen magnum and then through the jugular foramen.
The spinal root is designed to innervate the sternocleidomastoid and the trapezius muscles. These are the muscles responsible for creating motion of the head, neck, and shoulders.
The ease of motion of these muscles would deteriorate should there be damage to the accessory nerve.
ACCESSORY NERVE DIAGRAM
Image: Accessory Nerve