The preganglionic nerve fibers ( lying in a ganglion before switching ) have their origin in the inferior salivator nucleus of the medulla oblongata (elongated marrow) and leave the cranial cavity with the glossopharyngeal nerve (IX cranial nerve ) through the jugular foramen .
The parasympathetic fibers retreat as the tympanic nerve after exiting the jugular foramen back into the bony base of the skull. After a short course in the canaliculus tympanicus in the bone between the jugular foramen and carotid canal reach the fibers into the tympanic cavity ( Cavitas tympani ), where they together with the N. caroticotympanicus from the internal carotid plexus (from the neck cross-strand ) and a communicating branch from the intermediate part of the facial nerve form the tympanic plexus . The fibers of this plexus eventually converge to the minor petrosal nerve , which mainly carries preganglionic parasympathetic fibers. It leaves the temporal bone on its front through the hiatus canalis nervi petrosi minoris (just caudal to the hiatus for the N. petrosus major), runs under the dura mater in an anteromedial direction to the foramen lacerum or to the fissura sphenopetrosa at the lateral edge of the foramen lacerum. After emerging from the fossa cranii media , the N. petrosus minor enters the fossa infratemporalis and runs to the ganglion oticum , which is medial to the foramen ovale and the division point of the nervus mandibularis . Here, the fibers are switched from pre- to postganglionic and are deposited via a communicating branch to the auriculotemporal nerve from the mandibular division of the trigeminal nerve (cranial nerve V.) to. The parasympathetic fibers of the glossopharyngeal nerve reach their destination (parotid gland) via another anastomosis to the facial nerve, through whose branches the fibers in the parotid gland are distributed.