Which nerve is primarily responsible for swallowing, salivation, and gag reflex?

The glossopharyngeal nerve is the primary nerve responsible for several important functions, including swallowing, salivation, and the gag reflex. It is a mixed nerve, meaning it contains both motor and sensory fibers. The motor components are involved in the movement of the muscles in the throat that are crucial for swallowing, while the sensory fibers provide taste sensation from the posterior part of the tongue and contribute to the gag reflex by detecting stimuli in the back of the throat. This combination of sensory and motor functions makes the glossopharyngeal nerve essential for these activities.

In contrast, the accessory nerve primarily controls the sternocleidomastoid and trapezius muscles, which are involved in head movement and shoulder elevation, rather than in swallowing or salivation. The hypoglossal nerve is mainly responsible for the movement of the tongue, which is important for speech and swallowing but does not directly handle the gag reflex or salivation. The vagus nerve plays a role in autonomic functions including some aspects of swallowing and heart rate, but it is not the primary nerve associated with the gag reflex or salivation.