Toro-Ibacache Viviana, O'Higgins Paul
Centre for Anatomical and Human Sciences, Department of Archaeology and Hull York Medical School, University of York, Heslington, York, YO10 5DD, UK.
Facultad De Odontología, Universidad De Chile, Sergio Livingstone Pohlhammer 943, Independencia, Región Metropolitana, Chile.
Anat Rec (Hoboken). 2016 Jul;299(7):828-39. doi: 10.1002/ar.23358. Epub 2016 May 10.
Finite element analyses simulating masticatory system loading are increasingly undertaken in primates, hominin fossils and modern humans. Simplifications of models and loadcases are often required given the limits of data and technology. One such area of uncertainty concerns the forces applied to cranial models and their sensitivity to variations in these forces. We assessed the effect of varying force magnitudes among jaw-elevator muscles applied to a finite element model of a human cranium. The model was loaded to simulate incisor and molar bites using different combinations of muscle forces. Symmetric, asymmetric, homogeneous, and heterogeneous muscle activations were simulated by scaling maximal forces. The effects were compared with respect to strain distribution (i.e., modes of deformation) and magnitudes; bite forces and temporomandibular joint (TMJ) reaction forces. Predicted modes of deformation, strain magnitudes and bite forces were directly proportional to total applied muscle force and relatively insensitive to the degree of heterogeneity of muscle activation. However, TMJ reaction forces and mandibular fossa strains decrease and increase on the balancing and working sides according to the degree of asymmetry of loading. These results indicate that when modes, rather than magnitudes, of facial deformation are of interest, errors in applied muscle forces have limited effects. However the degree of asymmetric loading does impact on TMJ reaction forces and mandibular fossa strains. These findings are of particular interest in relation to studies of skeletal and fossil material, where muscle data are not available and estimation of muscle forces from skeletal proxies is prone to error. Anat Rec, 299:828-839, 2016. © 2016 Wiley Periodicals, Inc.
在灵长类动物、古人类化石和现代人类中，越来越多地开展了模拟咀嚼系统负荷的有限元分析。鉴于数据和技术的限制，模型和负荷情况往往需要简化。一个存在不确定性的领域涉及施加于颅骨模型的力及其对这些力变化的敏感性。我们评估了施加于人类颅骨有限元模型的颌骨提升肌之间不同力大小的影响。使用不同的肌肉力组合对该模型进行加载，以模拟切牙和磨牙咬合。通过缩放最大力来模拟对称、不对称、均匀和不均匀的肌肉激活。比较了应变分布（即变形模式）和大小、咬合力以及颞下颌关节（TMJ）反作用力方面的影响。预测的变形模式、应变大小和咬合力与总施加肌肉力成正比，并且对肌肉激活的不均匀程度相对不敏感。然而，颞下颌关节反作用力和下颌窝应变会根据负荷的不对称程度在平衡侧和工作侧降低和增加。这些结果表明，当关注面部变形的模式而非大小时，施加肌肉力的误差影响有限。然而，不对称负荷程度确实会影响颞下颌关节反作用力和下颌窝应变。这些发现对于骨骼和化石材料的研究尤为重要，因为在这些研究中无法获得肌肉数据，并且从骨骼代理估计肌肉力容易出错。《解剖学记录》，299:828 - 839，2016年。© 2016威利期刊公司。
