Final answer:
The trigeminal nerve has both sensory and motor functions. While it is primarily involved in sensory functions, it also controls the muscles of chewing. It is also involved in the motor control of the gag reflex.
Step-by-step explanation:
The trigeminal nerve is a mixed nerve, meaning that it contains both sensory and motor fibers. While it is primarily involved in sensory functions, such as conveying somatosensory information from the face to the brain, it also has some motor functions.
The motor component of the trigeminal nerve is responsible for controlling the muscles of chewing. This can be tested by observing the patient's ability to perform facial expressions, raise their eyebrows, smile, and frown, and by observing movements of the tongue, soft palate, or pharynx during swallowing or speaking.
Additionally, the motor control of the gag reflex, which is a test of the vagus nerve, involves fibers in the trigeminal nerve, as the parasympathetic functions of the vagus nerve are involved in regulating the gag reflex.