CRANIAL NERVE XI: SPINAL ACCESSORY NERVE

Two Roots:

1. Spinal Root: Gives SVE (Branchial) innervation to Sternocleidomastoid and Trapezius muscles.
2. Cervical Root: Quickly joins up with Vagus (and could be considered part of Vagus) to form the Recurrent Laryngeal Nerve.

NERVE GRAFTS: The function of Spinal Accessory is somewhat redundant.

• It can be used to replace innervation lost by other muscles. The nerve can be redirected to the muscles of facial expression, e.g., and patients can learn to use the new pathway with physical therapy.

DAMAGE TO SPINAL ACCESSORY:

• Shoulder Droop, due to lost innervation to upper part of Trapezius.
• Difficulty in turning head, due to lost innervation to Sternocleidomastoid -- but other muscles serve this function as well!

MOTOR CELL BODIES: Lie in the spinal cord (C1-C5).

• Fibers run up the spinal chord and into the cranium through the Foramen Magnum, and then back out the posterior cranial fossa through the Jugular Foramen.

Category: Anatomy Notes