Tympanic membrane retraction tensa. Tympanic membrane retraction is fairly common and has been observed in one quarter of a population of British school children. Retraction of both eardrums is less common than having a retraction in just one ear. It is more common in children with cleft palate. Tympanic membrane retraction also occurs in adults. Attempts have been made to categorise the extent of tympanic membrane retraction though the validity of these classifications is limited. The majority of tympanic membrane retractions do not cause any symptoms. Some cause hearing loss by restricting sound-induced vibrations of the eardrum. Permanent conductive hearing loss can be
Mastoid part of the temporal bone be distinguished from the mastoid cells, though it communicates with them. Like the mastoid cells it is filled with air and lined by a prolongation of the mucous membrane of the tympanic cavity, with which it communicates. The tympanic antrum is bounded above by a thin plate of bone, the tegmen tympani, which separates it from the middle fossa of the base of the skull; below by the mastoid process; laterally by the squama just below the temporal line, and medially by the lateral semicircular canal of the internal ear which projects into its cavity. It opens in front into