Tympanic membrane retraction caused by erosion of the ossicles (hearing bones). Discharge from the ear often indicates that the retraction pocket has developed into a cholesteatoma. Three factors must occur for the tympanic membrane to become retracted: When gas pressure within the middle ear is less than atmospheric pressure, the eardrum can become sucked into the middle ear space. This is caused by inadequate opening of the Eustachian tube and absorption of air from the middle ear space. People with a patulous Eustachian tube may also cause negative middle ear pressure by repeatedly sniffing to try to keep their Eustachian tube closed. The
Tympanic nerve Tympanic nerve The tympanic nerve (nerve of Jacobson) is a branch of the glossopharyngeal nerve found near the ear. It arises from the petrous ganglion, and ascends to the tympanic cavity through a small canal, the inferior tympanic canaliculus, 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. The postganglionic parasympathetic fibers are