The coronoid process provides attachment to temporalis and masseter muscles, and thus plays an important role in mastication. Tendons connect muscles and bones, mediating the transmission of functional loads to bones. Thus, tendon–bone entheses govern mechanical stress in bones. The preferential orientation of biological apatite (BAp) crystallites, the main mineral component in bones, is an important index for bone quality and function, and is largely influenced by locally applied stress. In this study, we analyzed BAp orientation, Young's modulus, and bone mineral density (BMD) at different sites in the human coronoid process. No differences in BMD were found among the analyzed sites, but BAp crystal orientation was observed to differ. BAp crystallites showed a uni‐directional orientation in the mesiodistal direction at the coronoid process apex, but were oriented in the direction vertical to the occlusal plane at other sites. Young's modulus tended to vary according to the BAp orientation. At the apex, a tendon form with characteristics different from those at other sites, including the presence of a fibrocartilaginous layer that may act as a stretching brake to control stress concentration, was observed. These findings suggest that the functional pressure of the temporalis muscle affects bone quality and strength.

中文翻译：

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人类下颌骨冠突和腱骨附着点的微骨和纳米骨分析。

冠突提供对颞肌和咬肌的附着，因此在咀嚼中起重要作用。肌腱连接肌肉和骨骼，调节功能负荷向骨骼的传输。因此，肌腱-骨附着点控制着骨骼中的机械应力。生物磷灰石 (BAp) 微晶是骨骼中的主要矿物成分，其优先取向是骨骼质量和功能的重要指标，并且在很大程度上受局部施加的应力影响。在这项研究中，我们分析了人类冠状突过程中不同部位的 Bap 取向、杨氏模量和骨矿物质密度 (BMD)。在分析的位点之间没有发现 BMD 差异，但观察到 BAp 晶体取向不同。BAp 微晶在冠突顶点近远中方向呈单向取向，但在其他部位则呈垂直于咬合面的方向。杨氏模量倾向于根据 BAp 取向而变化。在顶点处，观察到具有与其他部位不同的特征的肌腱形式，包括纤维软骨层的存在，其可以作为拉伸制动器来控制应力集中。这些发现表明颞肌的功能压力会影响骨骼质量和强度。观察到包括纤维软骨层的存在，该层可以作为拉伸制动器来控制应力集中。这些发现表明颞肌的功能压力会影响骨骼质量和强度。观察到包括纤维软骨层的存在，该层可以作为拉伸制动器来控制应力集中。这些发现表明颞肌的功能压力会影响骨骼质量和强度。