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Superquadric modeling of cranial asymmetry
Abstracts
295
THE FUNCTIONAL SIGNIFICANCE OF THE FIBULA AS DESCRIBED BY DIFFERENCES IN HUMAN AND CHIMPANZEE’ S.P. McLean and M. Marzke Departments of Exercise Science and Physical Education and Anthropology Arizona State University, Tempe, AZ 852874404, USA. A comparison of human (n= 15) and chimpanzee (closest evolutionary relative) (n= 17) fibtda with regard for cortical thickness was used to address the timctional significance of this bone. Computerized tomography was used to scan sites from 20% to 80% of the bone’s total length in 15% increments. Cortical thickness was digitized on the medial, lateral, anterior, and posterior aspects at each site and normalized to the total bone length. A discriminant analysis, used to determine group membership, was followed-up by t-tests to determine significaut differences betweeu species. Results indicated that with the exception of one site on the posterior aspect, a11sites on the anterior, posterior and medial aspects diacrituinated between the chimpanzee and human. The lateral aspect was different only at the extreme scau sites (20% and 80%). All discriminating sites were significantly different @<0.05) indicating that the chimpanzee exhibited consistently thicker cortical bone. This may have been due to an increased reliance on this bone for weight bearing and also an increased use of the muscles attaching to this bone. Insufficient evidence was found to suggest that the fibula was insignificant in the human skeleton. + We thank the Primate Foundation of Arizona for use of their skeletal primate collection and Scottsdale Memorial Hospital for use of and technical assistance with their CT scanner.
Superquadric Modeling of Cranial Asymmetry T. Y. Shiang, H.J. Sommer, and R.B. Eckhardt Departments of Mechanical Engineering and Anthropology The Pennsylvania State University, University Park, PA 16802, USA Cranial and cerebral asymmetry have been hypothesized as correlates of cerebral lateralization which in turn has been shown to be related to aphasia, dyslexia, stuttering, autism, and even some immune system disorders. To help more accurately assess asymmetry, a new method has been developed to fit symmetric superquadric geometric models to three dimensional coordinate measurements from cranial and cerebral surfaces. Asymmetry is then quantified as statistical deviations of the surface data points from their best-tit superquadric models. Three dimensional coordinates of random locations on external surfaces of 20 human skulls were measured experimentally and modeled using superquadric shapes. Polar contour plots of asymmetry are presented to demonstrate the efficacy of the method.
Center of Mass of Trunk Segments relative to the Spine as Determinedby ComputedTomography D.J. Pearsall’, J.G. ReWb, L.A. Livingston’ ’ Department
of Anatomy, Queen’s Univenity
’ School of Physical and Health Educaion,
’ Department of F’hydcal Education, Wiliiid
Queen’s Univenity
Laurier University
This study employed CT imaging technology to determine in viw, the location of the center of mass of discrete segments of the human torso with respect to the three c.ardinaI ru.tatomicaI planes. Four subjects, two male and two female (ages 46 to 68 yrs), had serial CT scans collected at 1 cm intervals for the full length of the trunk. The grey scale of the scans was correlated to tissue densities, thus, enabrmg trunk section mass properties to be calculated. The findings of this study differed from previous reporta. The center of mass and center of volume of vertebraI trunk segments were shown to be coincident except in the mid-thoracic region. With regards to the vertebral centroids of the spine, the respective center of mass was found to coincide along the anteropo&rior axis. However, in the sagitud plane, the ceuter of mass locations were found to be anterior to most of the vertebral centroids, contrary to popular belief. The centers of mass of the upper and lower torso segments were found to be similar to volumetric estimation techniques in the transverse plane but varied in the longitudinal direction. This study has provided insight into the mass distribution properties of the human torso that is of significance for use in biomechanical modeling of the trunk and spine.
295
THE FUNCTIONAL SIGNIFICANCE OF THE FIBULA AS DESCRIBED BY DIFFERENCES IN HUMAN AND CHIMPANZEE’ S.P. McLean and M. Marzke Departments of Exercise Science and Physical Education and Anthropology Arizona State University, Tempe, AZ 852874404, USA. A comparison of human (n= 15) and chimpanzee (closest evolutionary relative) (n= 17) fibtda with regard for cortical thickness was used to address the timctional significance of this bone. Computerized tomography was used to scan sites from 20% to 80% of the bone’s total length in 15% increments. Cortical thickness was digitized on the medial, lateral, anterior, and posterior aspects at each site and normalized to the total bone length. A discriminant analysis, used to determine group membership, was followed-up by t-tests to determine significaut differences betweeu species. Results indicated that with the exception of one site on the posterior aspect, a11sites on the anterior, posterior and medial aspects diacrituinated between the chimpanzee and human. The lateral aspect was different only at the extreme scau sites (20% and 80%). All discriminating sites were significantly different @<0.05) indicating that the chimpanzee exhibited consistently thicker cortical bone. This may have been due to an increased reliance on this bone for weight bearing and also an increased use of the muscles attaching to this bone. Insufficient evidence was found to suggest that the fibula was insignificant in the human skeleton. + We thank the Primate Foundation of Arizona for use of their skeletal primate collection and Scottsdale Memorial Hospital for use of and technical assistance with their CT scanner.
Superquadric Modeling of Cranial Asymmetry T. Y. Shiang, H.J. Sommer, and R.B. Eckhardt Departments of Mechanical Engineering and Anthropology The Pennsylvania State University, University Park, PA 16802, USA Cranial and cerebral asymmetry have been hypothesized as correlates of cerebral lateralization which in turn has been shown to be related to aphasia, dyslexia, stuttering, autism, and even some immune system disorders. To help more accurately assess asymmetry, a new method has been developed to fit symmetric superquadric geometric models to three dimensional coordinate measurements from cranial and cerebral surfaces. Asymmetry is then quantified as statistical deviations of the surface data points from their best-tit superquadric models. Three dimensional coordinates of random locations on external surfaces of 20 human skulls were measured experimentally and modeled using superquadric shapes. Polar contour plots of asymmetry are presented to demonstrate the efficacy of the method.
Center of Mass of Trunk Segments relative to the Spine as Determinedby ComputedTomography D.J. Pearsall’, J.G. ReWb, L.A. Livingston’ ’ Department
of Anatomy, Queen’s Univenity
’ School of Physical and Health Educaion,
’ Department of F’hydcal Education, Wiliiid
Queen’s Univenity
Laurier University
This study employed CT imaging technology to determine in viw, the location of the center of mass of discrete segments of the human torso with respect to the three c.ardinaI ru.tatomicaI planes. Four subjects, two male and two female (ages 46 to 68 yrs), had serial CT scans collected at 1 cm intervals for the full length of the trunk. The grey scale of the scans was correlated to tissue densities, thus, enabrmg trunk section mass properties to be calculated. The findings of this study differed from previous reporta. The center of mass and center of volume of vertebraI trunk segments were shown to be coincident except in the mid-thoracic region. With regards to the vertebral centroids of the spine, the respective center of mass was found to coincide along the anteropo&rior axis. However, in the sagitud plane, the ceuter of mass locations were found to be anterior to most of the vertebral centroids, contrary to popular belief. The centers of mass of the upper and lower torso segments were found to be similar to volumetric estimation techniques in the transverse plane but varied in the longitudinal direction. This study has provided insight into the mass distribution properties of the human torso that is of significance for use in biomechanical modeling of the trunk and spine.