Department of Anatomy, Jagiellonian University Medical College, Kraków, Poland.
Department of Oromaxillofacial Surgery, Ludwig-Maximilians-University Munich, Munich, Germany.
Aesthetic Plast Surg. 2024 Jul;48(14):2722-2729. doi: 10.1007/s00266-024-03876-8. Epub 2024 Feb 27.
Our understanding of facial anatomy has significantly evolved, yet the detailed contraction patterns of facial muscles and their presentation during clinical imaging remain largely unexplored. Understanding the contraction patterns and visual presentation of these muscles, particularly the zygomaticus major could enhance pre-surgical facial assessments and the development of new treatment strategies.
A total of 34 healthy young individuals (17 female, 17 male) with a mean age of 23.6 (2.4) years [range: 20-30] were investigated regarding the length, thickness, width, and angle of the zygomaticus major muscle in five different facial expressions (i.e., repose, anger, joy, surprise, and sadness) utilizing MR imaging.
Joyful expressions caused a reduction in muscle length to 85.6% of its original length and an increase in width (103.4%), thickness (108.4%), and facial angle (2.72°) when compared to that in repose, suggesting isotonic contraction. Conversely, expressions of anger, surprise, and sadness generally led to muscle stretching, seen through changes in length (98.9%, 104.3%, and 102.7%, respectively), width (98.8%, 96.5%, and 99.4%, respectively), and thickness (91.2%, 91.0%, and 102.7%, respectively), with variable alterations in facial angle (0.55°, 1.85°, and 1.00°, respectively) depending on the specific expression.
This MRI-based study indicates that the zygomaticus major muscle experiences isotonic contraction, characterized by decreased length and increased width and thickness. The findings underline the importance of muscle thickness as a reliable parameter in assessing facial muscle function and offer valuable guidance for practitioners in accurately evaluating muscle performance during different facial expressions.
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我们对面部解剖结构的理解已经有了显著的发展，但面部肌肉的详细收缩模式及其在临床影像中的表现仍在很大程度上未被探索。了解这些肌肉的收缩模式和视觉表现，特别是颧大肌，可以增强术前面部评估和新治疗策略的发展。
共纳入 34 名健康的年轻个体（17 名女性，17 名男性），平均年龄 23.6（2.4）岁[范围：20-30]，利用磁共振成像（MRI）研究在 5 种不同的面部表情（即休息、愤怒、喜悦、惊讶和悲伤）中颧大肌的长度、厚度、宽度和角度。
与休息时相比，喜悦表情导致肌肉长度减少到原始长度的 85.6%，宽度增加（103.4%），厚度增加（108.4%），面部角度增加（2.72°），表明等张收缩。相反，愤怒、惊讶和悲伤的表情通常会导致肌肉伸展，通过长度的变化（分别为 98.9%、104.3%和 102.7%）、宽度（分别为 98.8%、96.5%和 99.4%）和厚度（分别为 91.2%、91.0%和 102.7%）观察到，面部角度（分别为 0.55°、1.85°和 1.00°）会根据特定的表情而发生变化。
这项基于 MRI 的研究表明，颧大肌经历等张收缩，表现为长度缩短，宽度和厚度增加。这些发现强调了肌肉厚度作为评估面部肌肉功能的可靠参数的重要性，并为从业者在评估不同面部表情时准确评估肌肉性能提供了有价值的指导。
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