The Tympanic Nerve (n. tympanicus; nerve of Jacobson) 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. This plexus gives off:
(1) the lesser superficial petrosal nerve;
(2) a branch to join the greater superficial petrosal nerve; and
(3) branches to the tympanic cavity, all of which will be described in connection with the anatomy of the middle ear.