Gag reflex

Gag reflex. Stimulation of the posterior third of the tongue or posterior oropharynx sends afferent stimuli via the glossopharyngeal (ninth cranial) nerve. The efferent pathway involves the vagus (tenth cranial) and accessory (eleventh cranial) nerves, causing elevation of the soft palate and contraction of the pharyngeal muscles. Putting a spatula against the back of the mouth will normally elicit this reflex and thus test three different cranial nerves.