cranial nerve XI
accessory nerve
A nerve of the neck.Origin
Roots in lateral medulla oblongata and upper spinal cord.
Course
After multiple roots join, the AN divides into internal (cranial) and external (spinal) branches.
Distribution
Internal branch innervates vagus—palate, pharynx, larynx, thoracic viscera; external branch innervates sternocleidomastoid and trapezius muscles.
Type
Parasympathetic, motor.
Pathology
AN lesions cause drooping of the shoulder and inability to rotate the head away from the affected side.