What is the primary sensory function of the glossopharyngeal nerve (CN IX)?

The glossopharyngeal nerve (CN IX) is primarily responsible for taste sensations from the posterior one-third of the tongue. This cranial nerve is crucial for sensory input related to taste, as well as contributing to swallowing and the gag reflex. It innervates the taste buds located in the posterior aspect of the tongue, providing the brain with information about flavors, which is essential for appetite and digestion.

In addition to taste, the glossopharyngeal nerve also has other functions, such as providing sensory innervation to the oropharynx, conveying information about the general sensation of the pharynx, and contributing to various autonomic functions. However, its key role in taste perception from the posterior one-third of the tongue distinguishes it as the primary sensory function of this nerve.