Preuschoft H, Witzel U
Abteilung Funktionelle Morphologie, Anatomisches Institut, Medizinische Fakultät, Ruhr-Universität Bochum, Bochum, Germany.
Folia Primatol (Basel). 2004 Jul-Aug;75(4):219-52. doi: 10.1159/000078936.
Finite elements stress analysis (FESA) was used to investigate the flow of compressive forces which occur if a homogenous, three-dimensional body representing the skull is loaded by simulated bite forces against the tooth row. Model 1 represents the snout alone. Bite forces are applied simultaneously, but increase rearward. Stresses in the model concentrate along the anterior contour and the lower surface of the model, leaving unstressed a nasal opening and a wide naso-oral connection. Model 2 represents the facial region, as far as the temporomandibular joint. The orbits and the nasal cavity are assumed to be present a priori. Model 3 applies reactions to the bite forces in the temporal fossa, corresponding to the origins of the masticatory muscles. Regions of the model under compressive stress correspond closely to the arrangement of bony material in a hominoid skull. If only the stress-bearing finite elements on each section are combined, and the stress-free parts neglected, the resulting three-dimensional shape is surprisingly similar to a hominoid skull. If bite forces are applied to parts of the tooth row only, the stress patterns are lower, asymmetrical and do not spread into all regions that are stress-bearing in simultaneous biting on all teeth. In model 2, the highest stresses occur at the tooth roots and along the forehead on top of the nasal roof. There are no marked stress concentrations on top of the orbits. The resulting shape resembles that of an orang-utan. In model 3, the highest stresses also occur at the tooth roots, but the circles of force mostly close below the brain case, so that the stress concentration in the forehead region remains much less marked. In this model, however, the stress concentrations are very similar to hollow brow ridges. The entire resulting shape resembles that of gorilla or chimpanzee skulls. A typical gracile australopithecine skull (STS-5) also shows clear similarities to the patterns of stress flow in our models. Compared to our earlier study of the modern human skull, differences relate to: the relative length and width of the dental arcade, the relative size of the brain case and the position of the arcade relative to the brain case. It seems that these traits are the points of attack of selective pressures, while all other morphological details are simply consequences of stress flow.
有限元应力分析（FESA）被用于研究当一个代表颅骨的均质三维物体受到模拟咬合力作用于齿列时所产生的压缩力流动情况。模型1仅代表口鼻部。咬合力同时施加，但向后增加。模型中的应力集中在模型的前部轮廓和下表面，鼻腔开口和宽阔的鼻口连接区域无应力。模型2代表面部区域，直至颞下颌关节。眼眶和鼻腔被假定为预先存在。模型3对颞窝中的咬合力施加反作用力，对应咀嚼肌的起点。模型中承受压缩应力的区域与类人猿颅骨中的骨质排列紧密对应。如果仅将每个截面的承力有限元组合起来，而忽略无应力部分，所得的三维形状惊人地类似于类人猿颅骨。如果咬合力仅施加于齿列的部分区域，应力模式较低、不对称，且不会扩散到同时咬所有牙齿时承受应力的所有区域。在模型2中，最高应力出现在齿根处以及鼻顶上方的额头处。眼眶顶部没有明显的应力集中。所得形状类似于猩猩的形状。在模型3中，最高应力也出现在齿根处，但力的循环大多在脑壳下方闭合，因此额头区域的应力集中仍然不太明显。然而，在这个模型中，应力集中与中空的眉脊非常相似。整个所得形状类似于大猩猩或黑猩猩的颅骨。一个典型的纤细南方古猿颅骨（STS - 5）也与我们模型中的应力流动模式有明显相似之处。与我们早期对现代人类颅骨的研究相比，差异在于：牙弓的相对长度和宽度、脑壳的相对大小以及牙弓相对于脑壳的位置。似乎这些特征是选择压力的攻击点，而所有其他形态细节仅仅是应力流动的结果。
