Final answer:
The facial nerve (CN VII) is responsible for conveying taste sensation to the anterior two-thirds of the tongue and also plays a role in salivation. The glossopharyngeal nerve (CN IX) and the vagus nerve (CN X) provide taste to the posterior one-third and the extreme posterior, respectively.
Step-by-step explanation:
The cranial nerve responsible for providing taste to the anterior two-thirds of the tongue is the facial nerve (CN VII). The facial nerve is involved in taste sensation as well as salivation in the anterior oral cavity. When gustatory cells are activated by taste molecules, they release neurotransmitters onto the dendrites of sensory neurons that are part of the facial nerve, which connects to taste buds in the anterior two-thirds of the tongue. In contrast, the glossopharyngeal nerve (CN IX) conveys taste from the posterior one-third of the tongue, and the vagus nerve (CN X) handles taste sensation in the extreme posterior of the tongue and contributes to the gag reflex.
The role of the facial and glossopharyngeal nerves goes beyond taste; they also monitor salivation and the general sensations of the pharyngeal walls. Additionally, the motor response of the gag reflex is mediated through the vagus nerve (CN X), which stimulates the contraction of skeletal muscles in the pharynx and larynx for functions such as swallowing and speech.