Which cranial nerves carry sensory information from the tongue, and which tastes do they primarily detect?

• A. Anterior two-thirds via CN VII; posterior one-third via CN IX; epiglottis/palate via CN X; detects sweet, sour, salty, bitter, and umami
• B. Anterior two-thirds via CN VII; posterior one-third via CN IX; epiglottis/palate via CN X; detects sweet and salty
• C. Anterior two-thirds via CN VII; posterior one-third via CN IX; epiglottis/palate via CN X; detects only sour and bitter
• D. Anterior two-thirds via CN V; posterior one-third via CN IX; epiglottis/palate via CN X; detects all tastes

Answer: (B)

Taste information from the tongue is carried by different cranial nerves depending on the region: the anterior two‑thirds sends taste through the facial nerve (via the chorda tympani), the posterior one‑third through the glossopharyngeal nerve, and the epiglottis and soft palate through the vagus nerve. The front part of the tongue is where sweet and salty tastes are most prominently detected by the facial nerve, while the back of the tongue primarily communicates bitter through the glossopharyngeal nerve, and the vagus handles taste signals from the epiglottis and palate. Among the options, the pairing that aligns with this distribution—front via CN VII, back via CN IX, epiglottis/palate via CN X, with sweet and salty being the primary tastes detected in the anterior region—is the best fit. The other choices either assign the wrong nerve to the anterior tongue (such as using a nerve that doesn’t convey taste) or imply a broader or different taste distribution than is commonly taught for these regions.