Structure and Origin
- The tympanic nerve contains sensory axons to the middle ear, including the internal surface of the tympanic membrane.
- Cell bodies of these sensory axons are located in the superior ganglion of the glossopharyngeal nerve.
- It also contains parasympathetic axons that continue as the lesser petrosal nerve to the otic ganglion.
- The otic ganglion gives off postganglionic parasympathetic neurons.
- The tympanic nerve arises from the inferior ganglion of the glossopharyngeal nerve (CN IX).
- The origin is in the jugular fossa.

Course
- The tympanic nerve passes through the petrous part of the temporal bone within the tympanic canaliculus.
- The canaliculus is situated within the bony ridge separating the carotid canal and the jugular foramen.
- It reaches the middle ear through this course.
- In the tympanic cavity of the middle ear, it ramifies upon the promontory of the tympanic cavity.
- This forms the tympanic plexus.

Sensory Distribution
- The tympanic nerve provides sensation to the middle ear (tympanic cavity).
- It also supplies the internal surface of the tympanic membrane, Eustachian tube, parotid gland, and mastoid air cells.

Parasympathetic Autonomic Distribution
- The tympanic nerve is the parasympathetic root of the otic ganglion.
- The otic ganglion provides secretomotor innervation of the parotid gland via the auriculotemporal nerve.
- It is involved in the salivatory reflex to increase salivation during chewing.

Variation
- The tympanic nerve usually arises from the inferior ganglion of the glossopharyngeal nerve.
- Rarely, it may arise from a higher part.
- Rarely, it may provide no parasympathetic fibers to the otic ganglion.