Anatomic variations of the cochlea and relations to other temporal bone structures.

A thorough knowledge of the normal range of variation of anatomy and topography of the cochlea is necessary for optimal reproduction of this structure and correct interpretation of the radiographs. Radiographic identification of incomplete cochlear coils is essential in the diagnosis of congenital malformations such as Modini's deformity. Furthermore, a diagnosis of otosclerosis/otospongiosis has to be based on recognition of changes in the otic capsule. The size and shape of the human cochlea and the normal ranges of variation of its dimensions were evaluated in 95 plastic casts, prepared from temporal bone specimens. The normal range of variation is fairly small, and is not age-dependent. Obvious digression from this range, associated with pertinent clinical symptoms, indicates an abnormality.