Physical Properties of Tympanic Membrane and Membrane and Membranous Labyrinth

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The mechanical properties of guinea pig and human tympanic membranes were measured by a microtension tester newly developed by us Guinea pig tympanic membranes were tested under various conditions. When the tensile rate was 4.17X10^<-4>m ・sec^<-1> fresh specimens were 8.8 times stronger for a tension appllied parallel to the radial fibers than for that applied at a right angle to the them No difference in tensile strength was seen when the tension was applied at a right angle to the radial fibers. When the tensile direction was parallel to the radial fibers, the posterior part was stronger than the anterior part. Two human tympanic membranes were measured under formalin fixation. The measured values were calculated into those of the fresh specimens based on the results of the guinea pig material. The adjusted values for fresh human specimens were 2.56 kgf . mm^<-2> at a right angle to the radial fibers and 3, 28 kgf . mm^<-2> parallel to them Applying the thin cylinder and shell theory, the breakage pressure of the human tympanic membrane was calculated to be 1.00-22.4 atmospheric pressure.Mechanical properties of the semicircular canals of guinea pig, frogs and water fishes, and of human membranous labyrinths were tested. Tensile strength of the semicircular canals of guinea pig frog and water fish was greater in the order of guinea pig frog and fish, In the human membranous labyrinth the saccular membrane was the weakest, followed by Reissner's membrane, the utricular membrane and the semicircular canal. These values were converted form tensile strength to breakage pressure. The breakage pressure of the saccular membrane was 64.0 mmHg