Ossicular vibration in human temporal bones.

Abstract

Vibration mode of the ossicles was investigated in twelve fresh human temporal bones using a video measuring system (VMS, Technical Insrtument). This system allows one to observe the ossicular vibration and to measure its vibration amplitude (up to 0. 2 micron) and phase angle. In this study the inner and middle ear was kept intact except for two small holes in the tympanic tegmen. These holes were for the observation of ossicular movement and were covered with a thin cover glass during the experiment. The vibration amplitude and phase angle of the umbo, malleus head, lenticular process and stapes head were measured at 19 frequencies between 0. 1 kHz and 4. 5 kHz.The umbo moved piston-like at 0. 1-0. 8 kHz and 2.6-4.5 kHz but in an ellipse at 1. 0-2.4 kHz.The malleus head showed elliptical movement with its long axis anteriorly tilted around 45 degrees from the direction of the umbo vibration at 0. 1 kHz. Both the lenticular process and stapes head showed similar movement ; piston-like in lower frequencies and elliptical in higher frequencies.The umbo, lenticular process and stapes head vibrated parallel at lower frequencies.The position, displacement and phase angle of the rotation axis of the ossicles was calculated based on the displacement and phase angle of the umbo, malleus head and lenticular process. The axis was around the level of the neck of the malleus in frequencies lower than the resonant frequency, beneath the level of the short process near the resonant frequency and at the top of the malleus head in higher frequencies.The average axis displacement was 0. 9 microns at 1 kHz but much smaller at frequecies lower than 0. 8 kHz or higher than 2 kHz. This suggests that such axis movement may reduce the efficiency of the middle ear sound transmission.

Analysis of dynamic behavior of human middle ear using a finite-element method

“…The vibration amplitude of the ossicles at the second resonance frequency was smaller than that at the first resonance frequency. At the first resonance frequency, our results were similar to the data of the temporal bones using a video measuring system done by Gyo et al (1987) and Aritomo (1989), except for the stapes vibration mode. This may be caused by the assumptions that the incudo-stapedial joint is fixed, there is no constraint of the stapes footplate movement in the transverse direction, and the effect of the stapedial muscle is not taken into consideration.…”

“…However, in this paper, these were evaluated from a comparison between the frequency response of the eardrum Although Gyo et al (1987) and Aritomo (1989) suggested the movement of the ossicular axis of rotation, in this paper, for the sake of avoiding the complexity of the analysis, the axis of rotation was assumed to be a fixed straight line from the anterior process of the malleus which was supported by the anterior malleal ligament, to the short process of the incus which was supported by the posterior incudal ligament. Boundary conditions of the displacement continuity were assumed at the incudo-mallear and incudo-stapedial joints.…”

“…mal subjects. Finally, the vibration patterns of the eardrum and ossicular chain obtained from the FEM analysis were compared with the experimental results obtained by means of time-averaged holography (Tonndorf and Khanna, 1972) and by using a video measuring system (Gyo et al, 1987;Aritomo, 1989). FXI52-10, 1988), which was the improved program of SAP-IV developed by Professor Wilson of California University, was used, and the program was run on a ACOS2020 in Tohoku University Computer Center.…”

Computer Aided Three-Dimensional Reconstruction and Modeling of Middle Ear Biomechanics by High-Resolution Computed Tomography and Finite Element Analysis

“…However, peaks around 800-900 Hz in this model are compatible with those in the measurement. Aritomo [15] reported that the individual difference in displacement of both the umbo and stapes footplate was larger at low frequencies and that some temporal bones showed a clear peak in amplitude at resonance frequency. Therefore, it is considered that the differences mentioned above are within the permissible range.…”

Effects of Individual Differences in Size and Mobility of the Middle Ear on Hearing

“…The reliability of the standard model has been verified in a previous paper (2) by comparing the measuring results obtained from temporal bones (12) - (14) , and in subjects (15) , with the numerical results obtained from the standard model. In essence, the individual middle ear should be remodeled completely by paying attention to the details of its shape; however, obtaining the clear shapes of the TM and ossicles in individuals has been difficult to date.…”