Temporal fascia function during human growth: biomechanical modelling to predict the impact of surgical intervention

在生长过程中，颅骨的硬组织和软组织相互作用，影响头骨的形状，作为对机械载荷的响应的骨重建。然而，产生负荷的软组织并不局限于关闭颌骨的肌肉(颞肌、咬肌和翼骨)，还包括复杂的韧带、肌腱和筋膜层。一个特别被忽视和/或研究不足的结构是颞筋膜。颞筋膜覆盖了我们头部一侧的整个颞肌，帮助下巴移动和咀嚼，并潜在地具有一系列重新分配颅面张力的功能，从引导颞肌的力量，到限制颧弓(颧骨)和由咬肌的力量引起的眼眶的弯曲。到目前为止，颞筋膜的结构和功能只在少数几个研究中被研究过，限制了我们对其功能意义的理解。然而，来自实验研究、组织学和力学测试的越来越多的证据表明，在生长和正常的颌骨功能过程中，颞筋膜具有更重要的功能作用。20世纪60年代S的实验工作表明，Cebus猕猴在永久性剥离颞筋膜后，颧弓发生了明显的骨形态变化。然而，在儿童颅面外科手术中去除颧弓上的颞筋膜对颅缝融合患者的影响还没有被研究过。计算生物力学模型提供了一种有希望的非侵入性方法来研究骨骼对外部负荷的反应。汽车和航空航天工程等行业已经在设计流程中实施了计算建模，通过模拟而不是生产来节省资金。医疗和健康行业已经开始使用生物力学模型来测试特定患者的植入物、手术结果，并了解更多关于我们在跑步过程中所经历的负荷。现在可以研究切除患者的颞筋膜是否会对颅骨内的应力分布和颌肌功能产生重大影响。因此，本项目的主要目的是通过建立、分析和验证人类头盖骨和颌骨肌肉的生物力学模型，探索颞筋膜的功能，表征其在颅面发育和咀嚼过程中的作用。到目前为止，在人类计算生物力学模型(如有限元分析)中还没有考虑到颞筋膜。当研究如上所述的颌关节功能和紊乱(例如，磨牙或磨牙症)以及颞筋膜功能时，这可能是有问题的。忽略颞筋膜可能会影响生物力学模型的准确性以及这些模型在颅面、上颌和牙科手术中的临床应用潜力，包括在尚未完全了解破坏性手术对颞区的影响的情况下。通过建立这些模型和探索颞筋膜的功能，我们希望能深入了解手术中去除颞筋膜的影响，以及它在正常颌骨功能和骨生长中的一般作用。

During growth, hard and soft tissues of the skull interact to influence skull shape as bone remodels in response to mechanical loading. However, the soft tissues that generate loads are not limited to the jaw closing musculature (temporalis, masseter, and pterygoids), but also consist of complex ligaments, tendons and fascial layers. One particularly overlooked and/or understudied structure is the temporal fascia. The temporal fascia covers the entire temporalis muscle on the side of our head, aiding in jaw movement and chewing, and potentially has a suite of functions to redistribute craniofacial strain, from directing temporalis muscle force, to limiting bending of the zygomatic arch (cheek bone) and orbit induced by the force of the masseter muscle.To date, the structure and function of the temporal fascia have only been investigated in a handful of studies, limiting our understanding of its functional significance. However, there is growing evidence from experimental studies, histology and mechanical testing, suggesting a more functionally significant role of the temporal fascia during growth and normal jaw function. Experimental work conducted in the 1960's showed distinct bone shape changes of the zygomatic arch in Cebus monkeys following permanent detachment of the temporal fascia. However, the impact of removal of the temporal fascia from the zygomatic arch during craniofacial surgery in children, a common procedure for patients with craniosynostosis, has not been investigated.Computational biomechanical models provide a promising non-invasive method of investigating bone responses to external loads. Industries such as the automotive and aerospace engineering, have implemented computational modelling into the design pipeline, saving money with simulations instead of production. The medical and health industry have started using biomechanical models to test patient-specific implants, the outcomes of surgery, and to learn more about the loads we experience during running. It is now possible to investigate whether the removal of the temporal fascia in a patient would have a significant impact on stress distribution within the skull, and function of the jaw muscles. This is especially relevant for children who are in a key stage of craniofacial growth when jaw muscles are loaded for the first time.As such, the primary purpose of this project is to explore the function of the temporal fascia, characterising its role during craniofacial growth and chewing, by building, analysing and validating biomechanical models of the human skull and jaw muscles. To date, the temporal fascia has never been incorporated into human computational biomechanical models (e.g., finite element analysis). This may be problematic when investigating jaw joint function and disorders (e.g., tooth grinding or bruxism), as well as temporal fascia function as mentioned above. Omitting the temporal fascia could potentially be impacting the accuracy of biomechanical models and the potential of these models for clinical uses in craniofacial, maxillary and dental surgeries, including where the impact of disruptive surgery to the temporal region is not fully understood. By building these models and exploring the function of the temporal fascia, we hope to provide insight into the impact of removing the temporal fascia during surgery, as well as its general role in normal jaw function and bone growth.