The two goals of osteoplastic trepanation of the middle ear spaces are first a direct inspection of the main areas of pathologies within the epitympanum and secondly a better understanding of the infected middle ear diseases through careful preparation and exposure of the pathologic processes. A new way of approval could be found by taking into account the anatomical and topographical realities and the possible deviations form normal cases. This opens a better understanding of all those variations. Without touching the microstructures of the tympanum their inspection and preparations are hereby made possible macro- and microscopically. This leads to the conclusion that the tympanic structures are involved in the formation and progression of infected middle ear diseases. The correlation of the "aeration pathways" and the "drainage outlets" of the middle ear as an interdepending functional unit can be seen by this new intrasurgical inspection-based on light- and electronic microscopic research of various authors-as well as through the fact that middle ear mucous membrane is a truly respiratory membrane with no difference to other aeration pathways as found in the nose. A of a summation of mucous membranes in the area of the diaphragma is that minor catarrhal inflammations will block this aeration pathway of the middle ear. At the same time an open tuba auditiva can be found in acute, subacute and chronic middle ear diseases. Our findings that the ventilation of the ear is in most cases blocked at the diaphragma and not at the tube leads to questions on the one hand regarding the function of diaphragma and to the opinion on the other that the ventilation system of the middle ear is divided in two sections by the diaphragma: An anterior section including tuba and hypomesotympanon and a posterior including epitympanon, aditus, antrum and the pneumatic cells of mastoid and pyramid. The anterior section still is ventilated through the tuba when blocked at the diaphragma, in the posterior one ventilation and drainage are blocked even by mildly infected processes. Longer lasting infections have severe consequences for these spaces and the tympanic membrane.