Van Eijden T M, Blanksma N G, Brugman P
Academic Center for Dentistry Amsterdam (ACTA), Department of Functional Anatomy, The Netherlands.
J Dent Res. 1993 Mar;72(3):599-606. doi: 10.1177/00220345930720030801.
Electromyographic (EMG) activity in the human masseter muscle was registered from six different sites, in the anterior, middle, and posterior regions of the superficial and deep layers of the muscle, during static clenching tasks (intercuspal and incisal), selected jaw movements (alternating protrusion/retrusion, right/left latero-deviation, and open/close excursions), and unilateral chewing on right and left sides. Peak-EMG amplitudes and the timing of the peaks were compared. Activity in the regions of the deep masseter was either higher (in mastication and intercuspal open/close excursions) or lower (incisal clenching) than the activities in the superficial masseter. Superficial and deep masseter also differed in their timing of peak EMG: During chewing, peak activity passed from superficial to deep in the balancing-side muscle, and from deep to superficial on the chewing side. During free latero-deviations, peak activity started in the deep masseter, when the jaw moved to the right side (i.e., the side of the muscle), and then passed to the superficial regions, after the jaw movement was reversed to the left side. In addition, within the deep masseter there existed clear anteroposterior differences in activation level (during incisal clenching and open/close excursions) and in timing (during latero-deviation). Such a differentiation of activity was not found in the superficial masseter.
在人类咬肌的静态紧咬任务（牙尖交错位和切牙位）、选定的下颌运动（交替前伸/后缩、右/左侧向偏斜以及张/闭口运动）以及左右侧单侧咀嚼过程中，从咬肌浅层和深层的前部、中部及后部六个不同部位记录肌电图（EMG）活动。比较了肌电图峰值幅度和峰值出现的时间。咬肌深层区域的活动在咀嚼和牙尖交错位张/闭口运动时高于咬肌浅层，而在切牙位紧咬时则低于咬肌浅层。咬肌浅层和深层在肌电图峰值出现时间上也存在差异：在咀嚼过程中，平衡侧肌肉的峰值活动从浅层转移至深层，而咀嚼侧则从深层转移至浅层。在自由侧向偏斜时，当颌骨向右侧（即肌肉所在侧）移动时，峰值活动始于咬肌深层，随后在颌骨运动转向左侧后转移至浅层区域。此外，在咬肌深层内，激活水平（在切牙位紧咬和张/闭口运动期间）和时间（在侧向偏斜期间）存在明显的前后差异。而在咬肌浅层未发现这种活动差异。
