Epitympanic diaphragm in the new-born.

A series of 80 temporal bones included four specimens from infection-free new-born children. The microdissections showed that the epitympanic diaphragm in the new-born consists, in addition to the position fixed ligamental folds and ossicles, of only two position changing duplicate folds. These were the lateral incudomalleal fold, separating the upper and lower lateral attics, and the tensor fold, separating the anterior epitympanum from the supratubal recess. All other duplicate folds present during the fetal development had disappeared, a finding in accordance with the study on fetuses by Hammar in 1902 and with our own microdissection findings in normal adult temporal bones. Folds in other locations, even if until lately considered as participants of a normal epitympanic diaphragm, are of inflammatory origin.