Final answer:
The accessory (XI) nerve is classified as a motor nerve. It is responsible for innervating specific muscles in the neck and shoulder, such as the sternocleidomastoid and trapezius muscles, and it does not carry sensory information. b) Motor.
Step-by-step explanation:
The accessory nerve, also known as cranial nerve XI (CNXI), is classified as a motor nerve. This classification is based on its function, which is to innervate certain muscles in the neck and shoulder. More specifically, the accessory nerve supplies the sternocleidomastoid and trapezius muscles, which are involved in movements like head rotation and shoulder elevation.
The distinction between sensory, motor, and mixed nerves is a fundamental concept in neuroanatomy. Sensory nerves carry sensory information into the brain, motor nerves send signals to muscles to elicit movement, and mixed nerves carry both types of fibers. However, the accessory nerve does not convey sensory information and is purely motor in its action.
The cranial nerves can be remembered through various mnemonics, but assessing each nerve's function is pivotal for understanding their classification. While some cranial nerves like the olfactory (CNI) and optic (CNII) are sensory, and others like trigeminal (CNV) and facial (CNVII) are mixed, the accessory nerve stands as a motor nerve solely focused on muscular control.