Sasa Anna, Kulvanich Sirima, Hao Naohito, Ita Reiko, Watanabe Masahiro, Suzuki Taku, Magara Jin, Tsujimura Takanori, Inoue Makoto
Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
Department of Community Dentistry and Gerodontology, Faculty of Dentistry, Thammasat University, Klongluang, Thailand.
Front Physiol. 2022 Jun 8;13:881891. doi: 10.3389/fphys.2022.881891. eCollection 2022.
It still remains unclear how the suprahyoid muscles function in bolus formation during mastication. This study aimed to investigate the contributory role of the suprahyoid muscles during mastication. A total of 20 healthy young volunteers were asked to perform tongue pressure generation tasks and unilateral mastication tasks using peanuts and two different types of rice crackers. Surface electromyographic (EMG) activity of the masseter and suprahyoid muscles and mandibular kinematics were recorded. Suprahyoid activity increased with increasing tongue pressure. Masticatory duration until the first deglutition differed significantly among the different foods; the harder the food, the longer the duration. This was also the case in masseter activity per masticatory cycle. Masticatory rate and suprahyoid activity per masticatory cycle were significantly higher during soft rice cracker mastication. Masseter activity was higher on the masticatory side than on the non-masticatory side, however, there was no difference in suprahyoid activity between the sides. Suprahyoid activity and jaw gape showed significant positive correlation in the early stage on both the masticatory and non-masticatory sides. The suprahyoid muscles functioned dominantly for jaw-opening during peanut mastication, and for bolus formation, especially in the late stage during soft rice cracker mastication. Bolus formation was performed dominantly on the masticatory side during rice cracker mastication. These findings clearly demonstrate a functional role of the suprahyoid muscles during mastication of solid foods from assessments using both EMG activity and mandibular kinematic recordings.
舌骨上肌群在咀嚼过程中如何参与食团形成仍不清楚。本研究旨在探讨舌骨上肌群在咀嚼过程中的作用。共有20名健康年轻志愿者被要求使用花生和两种不同类型的米饼进行舌压产生任务和单侧咀嚼任务。记录了咬肌和舌骨上肌群的表面肌电图（EMG）活动以及下颌运动学数据。舌骨上肌群的活动随着舌压的增加而增强。不同食物咀嚼至首次吞咽的持续时间存在显著差异；食物越硬，持续时间越长。每个咀嚼周期的咬肌活动情况也是如此。咀嚼软米饼时，每个咀嚼周期的咀嚼速率和舌骨上肌群活动显著更高。咀嚼侧的咬肌活动高于非咀嚼侧，然而，两侧舌骨上肌群的活动没有差异。在咀嚼侧和非咀嚼侧的早期阶段，舌骨上肌群的活动与下颌开口度呈显著正相关。在咀嚼花生时，舌骨上肌群主要起到打开下颌的作用，而在咀嚼软米饼时，尤其是在后期阶段，主要参与食团形成。在咀嚼米饼时，食团形成主要发生在咀嚼侧。这些发现通过肌电图活动和下颌运动学记录评估，清楚地证明了舌骨上肌群在固体食物咀嚼过程中的功能作用。
