Any structural anomaly of the glossopharyngeal nerve, the ninth paired cranial nerve (CN IX).
Comment:
The glossopharyngeal nerve originates in the medulla oblongata. It Innervates the oropharynx, carotid body and sinus, as well as the posterior third of the tongue (where it mediates taste sensation), the middle ear cavity and the Eustachian tube. Additionally, it innervates the stylopharyngeus muscle of the pharynx.