Wang Qian, Dechow Paul C
Department of Biomedical Sciences Texas A&M University College of Dentistry, Dallas, Texas.
Anat Rec (Hoboken). 2016 Dec;299(12):1801-1829. doi: 10.1002/ar.23448.
Typically the zygoma is a single bone in the facial skeleton whose shape uniquely copes with loads associated with mastication. Rarely but naturally, the zygoma is divided into two or more parts by supernumerary sutures. These extra intrazygomatic sutures are located at an area of critical morphological and biomechanical importance, yet their impacts have not been studied. In this study, the morphological and possible biomechanical consequences of the divided zygoma (DZ) were investigated in primates including rhesus macaques (Macaca mulatta), orangutans (Pongo abelii and P. pygmaeus), and modern humans (Homo sapiens). Results demonstrated that a unilateral supernumerary suture within the zygoma affected facial symmetry. The superior division of the divided zygoma was normally slender along with the adjacent frontal bone parts; while the inferior division of the divided zygoma was normally more robust, along with stronger temporal and maxillary bones. These were possible biomechanical consequences, in which the stresses incurred during normal masticatory activities were shunted from the upper face to the lower face, especially along the zygomatic arch. These findings revealed that the DZ condition would alter overall morphology of the midface of the affected side, and unfavorably affect the pattern of stress distribution in the loaded side of the face during mastication. The developmental mechanisms for the supernumerary sutures dividing the zygoma were unclear. Further insights into this rare condition may deepen our understanding of craniofacial form, adaptation, developmental plasticity, and evolution, and help to improve therapeutic philosophies in corrective and regenerative medicine. Anat Rec, 299:1801-1829, 2016. © 2016 Wiley Periodicals, Inc.
通常情况下，颧骨是面部骨骼中的一块单一骨头，其形状独特地应对与咀嚼相关的负荷。罕见但自然的情况是，颧骨会被额外的缝骨分成两个或更多部分。这些额外的颧内缝骨位于一个具有关键形态学和生物力学重要性的区域，但它们的影响尚未得到研究。在本研究中，对包括恒河猴（猕猴属）、猩猩（婆罗洲猩猩和苏门答腊猩猩）以及现代人类（智人）在内的灵长类动物中颧骨分裂（DZ）的形态学和可能的生物力学后果进行了研究。结果表明，颧骨内的单侧额外缝骨会影响面部对称性。分裂颧骨的上半部分通常与相邻的额骨部分一样细长；而分裂颧骨的下半部分通常更粗壮，同时颞骨和上颌骨更强壮。这些是可能的生物力学后果，其中正常咀嚼活动中产生的应力从上半面部转移到下半面部，尤其是沿着颧弓。这些发现表明，DZ情况会改变患侧中面部的整体形态，并对咀嚼时面部受力侧的应力分布模式产生不利影响。分裂颧骨的额外缝骨的发育机制尚不清楚。对这种罕见情况的进一步深入了解可能会加深我们对颅面形态、适应性、发育可塑性和进化的理解，并有助于改进矫正和再生医学中的治疗理念。《解剖学记录》，299:1801 - 1829，2016年。© 2016威利期刊公司。
