Final answer:
The accessory (XI) nerve is classified as a motor nerve, specifically responsible for directing motions like turning the head and shoulder elevation by innervating the sternocleidomastoid and trapezius muscles.
Step-by-step explanation:
The accessory (XI) nerve is classified as motor. This nerve, also known as the spinal accessory nerve, is strictly involved in motor functions. It does not have any sensory fibers and is responsible for innervating certain muscles in the neck, specifically the sternocleidomastoid and trapezius muscles. These muscles are involved in movements such as turning the head and elevating the shoulders.
Cranial nerves can be sensory, motor, or both (mixed). Sensory nerves are involved in carrying sensory information to the brain, while motor nerves are involved in commanding muscle movements. The accessory nerve is one of the 12 cranial nerves that are attached to the brain and is one of the five that are strictly motor. More than 100 different nerve functions are managed by the cranial and spinal nerves, emphasizing their importance in daily activities and bodily functions.