Mao J, Osborn J W
Department of Oral Biology, Faculty of Dentistry, University of Alberta, Edmonton, Canada.
J Dent Res. 1994 May;73(5):1112-20. doi: 10.1177/00220345940730051401.
Human individuals were hypothesized to use the same pattern of jaw muscle activity to produce the same bite force. To test this hypothesis, we used a 2-mm-thick force transducer to monitor the magnitude and direction of a bite force between a single pair of occluding first molars. Five subjects performed standardized bite force tasks. Six different magnitudes were tested, each in five directions. The surface electromyographic (EMG) activity in the left and right masseter and temporalis muscles was recorded, integrated, and normalized. Ratios of the EMG activity of paired muscles (e.g., the ratio of working temporalis and working masseter) were calculated for each bite force task. Each ratio was roughly constant for each direction of bite force, regardless of its magnitude. In contrast, when the magnitude of bite force was the same but the directions were different, the ratio was not constant. We conclude that the direction of a bite force, not its magnitude, determines the pattern of activity of jaw-closing muscles. The shared patterns of muscle activation may be the result of a subconscious optimization of jaw muscle forces to improve efficiency.
人类个体被假定使用相同的颌肌活动模式来产生相同的咬合力。为了验证这一假设，我们使用了一个2毫米厚的力传感器来监测一对咬合的第一磨牙之间咬合力的大小和方向。五名受试者执行标准化的咬合力任务。测试了六种不同的大小，每种大小在五个方向上进行测试。记录、整合并标准化左右咬肌和颞肌的表面肌电图（EMG）活动。为每个咬合力任务计算配对肌肉的EMG活动比率（例如，工作颞肌和工作咬肌的比率）。对于每个咬合力方向，每个比率大致恒定，无论其大小如何。相比之下，当咬合力大小相同但方向不同时，该比率并不恒定。我们得出结论，咬合力的方向而非大小决定了闭口肌的活动模式。肌肉激活的共享模式可能是颌肌力量下意识优化以提高效率的结果。
