Articular constraint, handedness, and directional asymmetry in the human second metacarpal

Anthropology Program, University of Northern British Columbia, 3333 University Way, Prince George, BC, Canada.
Journal of Human Evolution (Impact Factor: 3.73). 07/2008; 54(6):875-85. DOI: 10.1016/j.jhevol.2007.12.001
Source: PubMed


The hypothesis that functional adaptation of joint surfaces to mechanical loading occurs primarily through change in mass, density, and structure of subarticular trabeculae (the "articular constraint" model) is investigated through an analysis of directional asymmetry among three separate bone compartments in the human second metacarpal. Measures of midshaft cross-sectional geometry, osteometry of the distal epiphysis, and subarticular trabecular microarchitecture of the distal epiphysis (assessed by high-resolution microcomputed tomography) were determined for 29 paired male and female metacarpals from a well-preserved nineteenth-century Euro-Canadian historic cemetery sample. For each measure, asymmetry was quantified using both mean-difference and confidence-interval methods. Both methods found a significant right-hand bias for measures of structural strength in midshaft geometry, as has been previously noted for this sample. Articular size, however, exhibits a right-hand bias only with regard to mediolateral, and not dorsopalmar, dimensions, a result that may reflect directional asymmetry in hand breadth at the distal palmar arch. The most striking asymmetries occur for subarticular trabecular microarchitecture. The right metacarpal head exhibits greater bone volume fraction, bone surface density, trabecular number, connectivity, and a more platelike rather than rodlike structure. These outcomes confer greater resistance to both axial compressive and shear strains for the metacarpal head at the metacarpophalangeal arthrosis. In all, these results confirm and extend previous research documenting structural asymmetries and limb dominance and are consistent with the concept of articular constraint. They also suggest a morphological signal through which functional asymmetry associated with handedness in fossil hominins may be investigated.

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Available from: Benedikt Hallgrimsson, Jan 10, 2014
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    • "Outcomes in the human second metacarpal, confirm and extend previous research documenting structural asymmetries and limb dominance and are consistent with the concept of articular constraint. They also suggest a morphological signal through which functional asymmetry associated with handedness in fossil hominins may be investigated (Lazenby et al., 2008). "
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    ABSTRACT: Digital flexion creases are one of the external anatomical landmarks in the hand. In this study, we measured and compared the distances between the digital skin creases (haustra digiti) in the fingers of right-handed and left-handed individuals. We also recorded the digital formulae. No significant difference was detected between left and right-handed females and left and right handed males on distance of skin creases (p>0.05). No difference was detected on haustra digiti of the right handed females their own hands. Females who use their left hand had a significantly longer (p=0.48) distal haustra digiti segment on their right second finger than that of their left hand. However, no significant difference was detected between male individuals on their left and right hand all haustra digiti segments. The rate of hand digital formulae of 3>4>2>5>1 was 78.12% in left-handed females, 66.7% in left-handed males, 54.54% in right-handed females, and 78.57% in right-handed males. Our study has contributed to the literature on the morphological asymmetry of left-handed females.
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    • "Although such methodological issues have been recognized by many researchers (e.g., Fajardo and Müller, 2001; Ryan and Ketcham, 2002; Maga et al., 2006), these traditional methods have remained the standard due to computational limitations and, in particular, a lack of alternative methods for analyzing cortical or trabecular bone structure. Furthermore, rarely are both cortical and trabecular bone structure analysed together in the same study even though both are critical to the biomechanical behaviour of the overall structure (Lazenby et al., 2008; Ryan and Shaw, 2012). "
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    ABSTRACT: This study introduces a standardized framework for the holistic analysis of cortical and trabecular bone structure. This method, although applicable to all bones of the skeleton, is particularly useful for irregular-shaped or small bones for which the application of traditional methods has been especially challenging. Traditional analyses have quantified cortical or trabecular structure in only selected regions of a bone, such as single cross- sections of cortical bone or volumes of interest of trabecular structure in epiphyses.
    Palaeontologia Electronica 01/2014; 17(3):33A. · 2.08 Impact Factor
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    • "。很多研究表明两侧的肢骨并不是完全对称的, 而是存在着左右侧差异, 上肢骨主要表现为右侧优势 [7] [9] [10] [11] , 下肢骨多表现为稍偏左侧优势 [8] [12] [13] [14] 。导致人体体质特征两侧差异的主要原因可能与遗传、环境和生活状态等因素有关 [15] "
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    ABSTRACT: Paleoanthropologists have been paying more attention to human femoral crosssectional surface areas, shapes and bilateral asymmetry because of the application of this informations to human evolution, population differences, and survival movements. Traditional analyses of femoral cross-sections usually adopt methods of destructive cutting, or laborintensive model making. In this study, using 3D laser scanning, we nondestructively and conveniently get the outer contour of 20 paired femoral 3-D data from a modern Chinese population. With the software of CAD and method of geometric morphometrics, we examine bilateral asymmetry between the left and right femoral cross-sectional area and shape. The results indicate that bilateral asymmetry in femoral size and shape exists. Cross-sectional areas of paired femora have no significant differences in absolute values, but have significant differences in relative ones. Paired femora show flutuating asymmetry, rather than directional asymmetry. Moreover, significant differences on paired femoral cross-sectional shapes show fluctuating asymmetry. Directional asymmetry exists on paired femoral cross-sectional shapes, but it is not statistically significant. Average cross-sectional shapes and areas seem to indicate that human femora have a slight left-lateral dominance. Although the samples in this study are limited, and the conclusion need more specimens for further verification, our results show that using 3D laser scanning techniques, we can get data of femoral cross-sectional outer contour, and the methods of morphometric analysis does reveal some important information that traditional methods can not determine. This paper establishes a new method to examine bone asymmetry, and can be used for additional studies in human evolution.
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