Final answer:
The trigeminal nerve carries sensory information for touch, pain, and temperature sensations in the face, with designated nuclei in the brainstem processing each type of sensory input.
Step-by-step explanation:
The three sensory functions of the trigeminal nerve include the sensation of touch, pain, and temperature in the facial area. The trigeminal nerve's fibers carry somatosensory information which is then processed by different nuclei in the brainstem. Sensory discrimination tests, like the one using a cotton-tipped applicator, can reveal issues within the trigeminal system.