DEVELOPMENT OF THE EPITYMPANUM AND AUDITORY OSSICLE CHAIN IN PNEUMATIZATION OF THE TEMPORAL BONE

Abstract

Pneumatization of the temporal bones in 34 cases, 40 ears was carried out and their horizontal sections were made.Dimenssions of the epitympanums and auditory ossicles in the border of the epitympanum and mesotympanum by the planimeter, were then taken and on estimation of the ratio of both dimenssions were made.Furthermore, abnormal posstion or adhesion between epitympanum and auditory ossicle were also observed.The results are as followes.1) High correlation between dimensions of the horizontal-sected epitympanums and pneumatization of the temporal bones was seen. Namely, the more stronger the pneumatizations of the temporal bones, the more their dimenssions are wide, while the more repressed, the more nar- rowed.2) Individual difference, in the dimenssion of the horizontal-sected auditory ossicle, has been re-cognized, but the correlation between the former and pneumatizations of the temporal bones were not seen.3) The ratio of both dimenssions had high correlation to the pneumatization of the temporal bone.Namely, the better pneumatization of the tem-poral bones, the more the space between epitympa-num and auditory ossicle are wide, while on the contrary the more repressed, the more narrowed.4) In one out of 40 cases, the epitympanum was so markedly cellulated that a top of the cellulle-process was closed to the malleus and the short process of incus was attached to the bone wall.In this case, pneumatization of the temporal bone is the best. From results of 4) and our clinic experience, the author found the existence of the new type of the pseudo-otosclerosis.From these results author has the opinion that, the temporal bones of repressed pneumatisation are apt to be closed the space between the epitympanum and auditory ossicle more often than the well pne-umatized ones beeing caused by the pathological changes.Furthermore, the cause of epitympanal cholest-eatoma was also discussed. Author has the opinion from good cases results of 1), 2), and 3), that compared to relatively the cases of repressed pneumatization the temporal bone where closed space between the epitympanum and auditory ossicle was seen was caused by the patho-logical changes.Furthermore, the cause of epitympanal cholest-eatoma was also discussed.