Department of Community and Family Medicine, Duke University Medical Center, Durham, NC, USA.
J Anat. 2011 Nov;219(5):551-64. doi: 10.1111/j.1469-7580.2011.01424.x. Epub 2011 Sep 16.
One of the most prominent features of the cranial component of the temporomandibular joint (TMJ) is the articular eminence (AE). This bar of bone is the primary surface upon which the condyle translates and rotates during movements of the mandible, and is therefore the primary point at which forces are transmitted from the mandible to the cranium during loading of the masticatory apparatus. The shape of the AE is highly variable across primates, and the raised eminence of humans has often been considered a defining feature of the human TMJ, yet few data exist to address whether this variation is functionally significant. This study used a broad interspecific sample of anthropoid primates to elaborate upon and test the predictions of a previously proposed model of AE function. This model suggests that AE inclination acts to resist non-normal forces at the TMJ, thereby maximizing bite forces (BFs). AE inclination was predicted to covary with two specific features of the masticatory apparatus: height of the TMJ above the occlusal plane; and inclination of the masticatory muscles. A correlate of this model is that taxa utilizing more resistant food objects should also exhibit relatively more inclined AEs. Results of the correlation analyses found that AE inclination is strongly correlated with height of the TMJ above the occlusal plane, but less so with inclination of the masticatory muscles. Furthermore, pairwise comparisons of closely related taxa with documented dietary differences found that the AE is consistently more inclined in taxa that utilize more resistant food items. These data preliminarily suggest that variation in AE morphology across anthropoid primates is functionally related to maximizing BFs, and add to the growing dataset of masticatory morphologies linked to feeding behavior.
颞下颌关节（TMJ）颅部结构最显著的特征之一是关节结节（AE）。这块骨头是下颌在运动时，髁突平移和旋转的主要表面，因此，在咀嚼装置受力时，力量从下颌传递到颅骨的主要部位就在这里。AE 的形状在灵长类动物中变化很大，人类凸起的隆起常常被认为是人类 TMJ 的一个特征，但很少有数据可以证明这种变化在功能上是否具有重要意义。本研究使用了一个广泛的灵长类动物种间样本，详细阐述和检验了先前提出的 AE 功能模型的预测。该模型表明，AE 的倾斜度可以抵抗 TMJ 上的非正常力，从而最大限度地提高咬合力（BFs）。AE 的倾斜度被预测与咀嚼器官的两个特定特征有关：TMJ 高于咬合平面的高度；咀嚼肌的倾斜度。该模型的一个相关点是，使用更耐嚼的食物的类群也应该表现出相对更倾斜的 AE。相关分析的结果发现，AE 的倾斜度与 TMJ 高于咬合平面的高度密切相关，但与咀嚼肌的倾斜度的相关性较弱。此外，对具有不同饮食记录的密切相关的类群进行成对比较发现，AE 在使用更耐嚼的食物的类群中始终更倾斜。这些数据初步表明，灵长类动物的 AE 形态的变化与最大限度地提高 BF 有关，并增加了与摄食行为相关的咀嚼形态的不断增长的数据集。
