Cranial Nerve IX, The Glossopharyngeal Nerve
Cranial Nerve IX and X are tested by the gag reflex, or alternatively, having the patient say "Ah.." while looking for symmetrical elevation of the palate. The gag reflex is performed by touching the posterior pharyngeal wall with a tongue depressor. This reflex assumes an intact CN X, as the sensory portion of this reflex is mediated by CN IX, while the motor portion is mediated by CN X.