Which cranial nerve is responsible for taste sensation from the anterior two-thirds of the tongue in most mammals?

• A. Glossopharyngeal nerve (CN IX)
• B. Trigeminal nerve (CN V)
• C. Vagus nerve (CN X)
• D. Facial nerve (CN VII)

Answer: (D)

Taste from the anterior two-thirds of the tongue is carried by the special sensory fibers of the chorda tympani, a branch of the facial nerve (cranial nerve VII). These taste fibers ride with the lingual nerve to reach the tongue and innervate the taste buds there. This means the facial nerve is the one responsible for this specific taste sensation. The other nerves handle different roles: the glossopharyngeal nerve serves taste to the posterior one-third of the tongue, the vagus nerve contributes taste from the epiglottis area, and the trigeminal nerve provides general sensation (touch, pain) to the tongue but not taste.