Blanksma N G, van Eijden T M
Department of Functional Anatomy, Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands.
J Dent Res. 1995 Jun;74(6):1318-27. doi: 10.1177/00220345950740061201.
The human temporalis and masseter muscles are not activated homogeneously during static bite force tasks. In this study, we studied the possible existence of regional differences in these muscles under dynamic conditions. Electromyographic (EMG) activity was recorded by means of bipolar fine-wire electrodes. Six electrodes were inserted into the temporalis muscle and three into the masseter muscle. Recordings were made during maximal effort intercuspal and incisal static clenches, open/close excursions from both the intercuspal and incisal positions, and unilateral gum and licorice chewing on right and left sides. The EMG peak amplitudes and the peak occurrences were compared. During the static clenches and the open/close excursions, no differences could be demonstrated between the regions of the temporalis muscle. However, during the chewing tasks, the anterior and posterior regions behaved differently. Throughout almost all tasks, both superficial and deep parts could be distinguished in the masseter muscle. A further division of the deep masseter was task-dependent. In both the temporalis and masseter muscles, maximal activity (100%) was reached during intercuspal clenches. The average activity declined to 35% of the maximal activity in the temporalis muscle, to 47% in the deep, and to 86% in the superficial masseter during incisal clenches. During all chewing tasks, the EMG peak activity of the anterior temporalis and the superficial masseter muscles was higher in the working than in the balancing condition. The general finding was that different regions were preferentially activated, according to task. The detailed regional specialization previously observed during static bite force tasks could not be demonstrated in the present study.
在静态咬合力任务中，人类颞肌和咬肌的激活并非均匀一致。在本研究中，我们探究了在动态条件下这些肌肉中区域差异存在的可能性。通过双极细线电极记录肌电图（EMG）活动。将六个电极插入颞肌，三个电极插入咬肌。在最大用力的牙尖间和切牙静态咬合、从牙尖间和切牙位置进行的开闭运动以及左右侧单侧咀嚼口香糖和甘草的过程中进行记录。比较了EMG峰值幅度和峰值出现情况。在静态咬合和开闭运动期间，颞肌各区域之间未显示出差异。然而，在咀嚼任务期间，前部和后部区域表现不同。在几乎所有任务中，咬肌都可区分出浅层和深层部分。深层咬肌的进一步划分取决于任务。在颞肌和咬肌中，牙尖间咬合时均达到最大活动度（100%）。切牙咬合时，颞肌的平均活动度降至最大活动度的35%，深层咬肌降至47%，浅层咬肌降至86%。在所有咀嚼任务中，工作侧的颞肌前部和咬肌浅层的EMG峰值活动高于平衡侧。总体发现是，不同区域根据任务被优先激活。在本研究中未能证实先前在静态咬合力任务中观察到的详细区域特化情况。
