Glossopharyngeal Nerve

Cranial nerve IX arises from the medulla as three or four tiny filaments that quickly collect into one or, rarely, two rootlets passing forward and laterally, ventral to the choroid plexus, to penetrate the glossopharyngeal meatus.2'14 Cranial nerve IX then turns abruptly anteroinferiorly and, as it traverses the jugular foramen, gives rise to the tympanic branch (Jacobson's nerve) to the tympanic cavity. Along its course in the temporal bone, the tympanic branch of CN IX has many swellings formed by ganglion cells, a potential site of origin for glomus tumors. Cranial nerve IX exits the jugular foramen between the ICA and internal jugular vein and descends lateral to CN X and XI. More distally, CN IX passes anteriorly to cross the lateral surface of ICA deep to the styloid process, where it divides into several branches.

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