Calculation of Inertial Properties of the Malleus-incus Complex from Micro-ct Imaging

The middle ear bones are the smallest bones in the human body and are among the most complicated functionally. These bones are located within the temporal bone making them difficult to access and study. We use the micro-CT imaging modality to obtain quantitative inertial properties of the MIC (malleus-incus complex), which is a subcomponent of the middle ear. The principal moment of inertia of the malleus along the superior-inferior axis (17.3 ± 2.3 mg/mm3) is lower by about a factor of six in comparison to the anterior-posterior and lateral-medial axes. For the incus, the principal moment of inertia along the superior-inferior axis (35.3 ± 6.9 mg/mm3) is lower by about a factor of two than for the other two axes. With the two bones combined (MIC), the minimum principal moment of inertia (132.5 ± 18.5 mg/mm3) is still along the superior-inferior axis but is higher than for the individual bones. The superior-inferior axis inertia is lower by a factor of 1.3 than along the anterior-posterior axis and is lower by a factor 2 along the lateral-medial axis. Values for inertia of the MIC show significant individual differences in three human ears measured, suggesting that middle ear models should be based on individual anatomy. Imaging by micro-CT scanner is a nondestructive modality that provides threedimensional volume information about middle ear bones at each stage of manipulation with resolution down to 10�m. In this work extraneous tissue is removed to obtain a sufficiently small specimen. However, advances in imaging hold promise that this capability will be available for in vivo measurements. DOI: 10.2140./jomms2007.2.1515 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-53974 Originally published at: Sim, J H; Puria, S; Steele, C R (2007). Calculation of intertial properties of the malleus-incus complex from micro CT-imaging. Journal of Mechanics of Materials and Structures, 2(8):1515-24. DOI: 10.2140./jomms2007.2.1515 Journal of Mechanics of Materials and Structures CALCULATION OF INERTIAL PROPERTIES OF THE MALLEUS-INCUS COMPLEX FROM MICRO-CT IMAGING Jae Hoon Sim, Sunil Puria and Charles R. Steele Volume 2, No 8 October 2007 mathematical sciences publishers JOURNAL OF MECHANICS OF MATERIALS AND STRUCTURES Vol. 2, No. 8, 2007 CALCULATION OF INERTIAL PROPERTIES OF THE MALLEUS-INCUS COMPLEX FROM MICRO-CT IMAGING JAE HOON SIM, SUNIL PURIA AND CHARLES R. STEELE The middle ear bones are the smallest bones in the human body and are among the most complicated functionally. These bones are located within the temporal bone making them difficult to access and study. We use the micro-CT imaging modality to obtain quantitative inertial properties of the MIC (malleus-incus complex), which is a subcomponent of the middle ear. The principal moment of inertia of the malleus along the superior-inferior axis (17.3± 2.3mg/mm3) is lower by about a factor of six in comparison to the anterior-posterior and lateral-medial axes. For the incus, the principal moment of inertia along the superior-inferior axis (35.3± 6.9mg/mm3) is lower by about a factor of two than for the other two axes. With the two bones combined (MIC), the minimum principal moment of inertia (132.5± 18.5mg/mm3) is still along the superior-inferior axis but is higher than for the individual bones. The superior-inferior axis inertia is lower by a factor of 1.3 than along the anterior-posterior axis and is lower by a factor 2 along the lateral-medial axis. Values for inertia of the MIC show significant individual differences in three human ears measured, suggesting that middle ear models should be based on individual anatomy. Imaging by micro-CT scanner is a nondestructive modality that provides three-dimensional volume information about middle ear bones at each stage of manipulation with resolution down to 10μm. In this work extraneous tissue is removed to obtain a sufficiently small specimen. However, advances in imaging hold promise that this capability will be available for in vivo measurements.