Department of Anthropology, University of Arkansas, Fayetteville, Arkansas, USA.
College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia.
Anat Rec (Hoboken). 2022 Sep;305(9):2227-2248. doi: 10.1002/ar.24886. Epub 2022 Feb 14.
The temporomandibular joint is the direct interface between the mandible and the cranium and is critical for transmitting joint reaction forces and determining mandibular range of motion. As a consequence, understanding variation in the morphology of this joint and how it relates to other aspects of craniofacial form is important for better understanding masticatory function. Here, we present a detailed three-dimensional (3D) geometric morphometric analysis of the cranial component of this joint, the glenoid fossa, across a sample of 17 anthropoid primates, and we evaluate covariation between the glenoid and the cranium and mandible. We find high levels of intraspecific variation in glenoid shape that is likely linked to sexual dimorphism and joint remodeling, and we identify differences in mean glenoid shape across taxonomic groups and in relation to size. Analyses of covariation reveal strong relationships between glenoid shape and a variety of aspects of cranial and mandibular form. Our findings suggest that intraspecific variation in glenoid shape in primates could further be reflective of high levels of functional flexibility in the masticatory apparatus, as has also been suggested for primate jaw kinematics and muscle activation patterns. Conversely, interspecific differences likely reflect larger scale differences between species in body size and/or masticatory function. Results of the covariation analyses dovetail with those examining covariation in the cranium of canids and may be indicative of larger patterns across mammals.
颞下颌关节是下颌骨和颅骨的直接接口，对于传递关节反作用力和确定下颌运动范围至关重要。因此，了解这个关节形态的变化以及它与颅面形态的其他方面的关系，对于更好地理解咀嚼功能非常重要。在这里，我们对 17 种灵长类动物的颅部关节窝进行了详细的三维（3D）几何形态分析，并评估了关节窝与颅骨和下颌骨之间的协变关系。我们发现，关节窝形状的种内变异程度很高，这可能与性别二态性和关节重塑有关，并且我们还确定了在分类群和大小方面，关节窝形状的均值存在差异。协变分析揭示了关节窝形状与颅骨和下颌骨形态的多种方面之间存在强烈的关系。我们的研究结果表明，灵长类动物关节窝形状的种内变异可能进一步反映了咀嚼器官的高功能灵活性，这也与灵长类动物的颌部运动学和肌肉激活模式有关。相反，种间差异可能反映了物种之间在体型和/或咀嚼功能上的更大规模差异。协变分析的结果与对犬科动物颅骨协变的研究结果一致，这可能表明在哺乳动物中存在更大的模式。
