The tympanic plexus is a nerve plexus that is located on the cochlear promontory.
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Gross anatomy
The tympanic nerve (a branch of the glossopharyngeal cranial nerve) passes through the inferior tympanic canaliculus to emerge on the cochlear promontory of the middle ear, where it then divides into an anterior branch that travels towards the Eustachian tube and a posterior branch that travels towards the round window 1.
The anterior and posterior branches of the tympanic nerve form the tympanic plexus with a small contribution from the sympathetic fibers of the carotid plexus 2.
The tympanic plexus then gives off the lesser petrosal nerve which runs on the floor of the middle cranial fossa and supplies parasympathetic preganglionic fibers to the parotid gland.
The tympanic plexus also gives off branches that supply the mucous membranes of the tympanic cavity, the mastoid air cells and the auditory tube 2.
Variant anatomy
The tympanic plexus is a highly variable structure with respect to its course, branching and anastomoses, and there is often no bilateral symmetry.
History and etymology
The tympanic plexus has been referred to as the ‘Jacobson anastomosis’ plexus as it was originally described in the early 1800’s by Ludvig Levin Jacobson, a renowned anatomist from Copenhagen for whom the Jacobson nerve is also named 3.
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