tympanic plexus tympanic plexus the tympanic plexus is a nerve plexus within the tympanic cavity formed upon the promontory of tympanic cavity by the tympanic nerve (branch of the inferior ganglion of glossopharyngeal nerve (cn ix)), and the superior and inferior caroticotympanic nerves (post-ganglionic sympathetic branches of the carotid plexus). tympanic plexusview of the inner wall of the tympanum. (grooves for tympanic plexus labeled at center.)plan of the facial and intermediate nerves and their communication with other nerves. (tympanic plexus labeled at center.)detailsfromcaroticotympanic nerves, tympanic nerveidentifierslatinplexus tympanicusta98a14.2.01.140ta26324fma77533anatomical terms of neuroanatomy the lesser petrosal nerve (which may be considered a continuation of the tympanic nerve) traverses the tympanic plexus. anatomy distribution the tympanic plexus innervates the mucosa of the tympanic cavity, pharyngotympanic tube, and mastoid air cell. it issues a branch to the greater petrosal nerve (through an opening anterior to the oval window).