SPACIAL SITUATION AND AREAS OF THE TYMPANICMEMBRANE, THE OVAL AND THE ROUND WINDOWIN THE HUMAN TEMPORAL BONE

Abstract

1) The author measured three-dimensionally the angles between the planes of the tympanic membranes, the oval and the round windows on nine human temporal bones. After removal of the tympanic membrane, the ossicles and the round window membrane, the author made the plastic mould of the tympanic cavity.The planes representig the tympanic membrane, the oval and round window were ground on the mould, and then the angles between each plane were measured with three-dimensional goniometer. The angle was 17.4 degrees between the planes of the tympanic membrane and the oval window, 76, 9 degrees between the oval window and the round window and 69.8 degrees between the tympanic membrane and the round window.These were similar to those had been reported by others. 2) The labyrinths of eight human temporal bones were opened to expose the inner ear side of the oval and the round windows.Then the areas of the windows were measured on their photographs. The area of the oval and the round window was 3.4 mm2 and 2.6 mm2 respectively, and the ratio of the areas of the two windows was 1.3 to 1. This ratio was smaller than those reported by other authors.In some cases the round windows were as large as the oval windows, and as a whole the size of the round window seemed to be more variable than that of the oval window.