Taste on the posterior tongue is provided by which cranial nerve?

• A. Cranial Nerve VII (CN VII)
• B. Cranial Nerve IX (CN IX)
• C. Cranial Nerve X (CN X)
• D. Cranial Nerve II (CN II)

Answer: (B)

Taste from the posterior third of the tongue is carried by the glossopharyngeal nerve. It contains gustatory fibers that transmit information from that region to the brainstem (nucleus tractus solitarius), then onward to the thalamus and gustatory cortex. In contrast, the anterior two-thirds get taste via the facial nerve (through the chorda tympani), the epiglottis area can involve the vagus, and the optic nerve is unrelated to taste. So for the posterior tongue, the glossopharyngeal nerve is the correct carrier.