Tympanic nerve

The tympanic nerve (nerve of Jacobson) is a branch of the glossopharyngeal nerve found near the ear.

Path
It arises from the petrous ganglion, and ascends to the tympanic cavity through a small canal on the under surface of the petrous portion of the temporal bone on the ridge which separates the carotid canal from the jugular fossa.

In the tympanic cavity it divides into branches which form the tympanic plexus and are contained in grooves upon the surface of the promontory.

Jacobson's nerve contains both sensory and secretory fibers.
 * Sensory fibers supply the middle ear and parasympathetic secretory fibers serve the parotid gland.
 * The secretory fibers enter the otic ganglion.

The postganglionic parasympathetic fibers are then distributed via the auriculotemporal nerve (branch of the trigeminal nerve) to the parotid gland.

Clinical significance
This nerve may be involved by paraganglioma, in this location referred to as glomus jugulare or glomus tympanicum tumours.