A Biological Gear in the Human Middle Ear

H. Cai, R.P. Jackson, C. Steele, and S. Puria
Stanford University, Stanford, CA, USA
Publié en 2010

To support high frequency transmission, the mammalian middle ear construction is unique. The middle ear bones are connected through two mobile joints, the malleus-incus joint (MIJ) and the incudostapedial joint (ISJ). These synovial joints, consisting of joint capsule and synovial fluid inside, play an important role in sound transmission. We developed our current FE model using COMSOL that allows us to loft 2D geometric objects to construct complex 3D structures. The MIJ and ISJ were modeled as fluid-filled mobile joints. The geometry, including the ear canal, tympanic membrane , ossicular bones, suspensory soft attachments and middle ear joints, was based entirely on 3D reconstruction obtained from micro Computed Tomography (microCT) imaging. We solve the acoustics-structure interaction problem using COMSOL Multiphysics solvers. Our results show that at low frequencies, the classical hinging motion is dominant. However, at high frequencies, we observe multi-resonance vibration modes at the eardrum, rocking motions about the short and long axes of the stapes footplate, and a biological bevel-gear like response at the malleus-incus complex.

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