Blanksma N G, van Eijden T M, van Ruijven L J, Weijs W A
Academic Centre for Dentistry Amsterdam (ACTA), Department of Functional Anatomy, The Netherlands.
J Dent Res. 1997 Jan;76(1):542-51. doi: 10.1177/00220345970760010401.
The complex architecture of the human jaw muscles suggests regional differences in function within these muscles. This study examines the way the temporalis and masseter muscle regions are activated when free mandibular movements with various speeds and against various external leads are carried out guided by visual feedback. Electromyographic (EMG) activity was registered in six temporalis and three masseter muscle regions with bipolar fine-wire electrodes. Recordings were made during open/close excursions, protrusion/retrusion movements, and laterodeviations. During open/close excursions and protrusion/retrusion movements, an anterior and posterior temporalis part could be distinguished, whereas during laterodeviations a more complex partitioning of this muscle was observed. During the protrusion/retrusion movements and the laterodeviations, the temporalis muscle demonstrated higher EMG peak activities than the masseter muscle, and within the masseter muscle the deep masseter showed higher EMG peaks than the superficial one. In contrast to this, during the open/close excursions the masseter showed higher peak activities than the temporalis muscle, while the superficial masseter showed higher EMG peak activities than the deep masseter. Within the deep masseter, differences were also found. During open/close excursions, the anterior deep region demonstrated higher EMG peak activities than the posterior region, whereas during protrusion/retrusion and laterodeviations the posterior deep region showed higher peaks. In general, speed had a greater effect on the EMG peak activity than external load. Only during laterodeviations did speed and load equally influence peak activity in both the deep and superficial masseter. During protrusion/retrusion movements, load showed no significant effect on EMG peak activity in the masseter muscle. A general finding was that, according to task, different regions were activated preferentially. This points to a partitioning of the excitatory command of the motoneuron pool.
人类颌肌的复杂结构表明这些肌肉在功能上存在区域差异。本研究考察了在视觉反馈引导下进行不同速度和对抗不同外部负荷的自由下颌运动时，颞肌和咬肌区域的激活方式。使用双极细线电极记录了六个颞肌区域和三个咬肌区域的肌电图（EMG）活动。记录在开口/闭口运动、前伸/后缩运动以及侧方偏斜过程中进行。在开口/闭口运动和前伸/后缩运动中，可以区分颞肌的前部和后部，而在侧方偏斜过程中观察到该肌肉有更复杂的分区。在前伸/后缩运动和侧方偏斜过程中，颞肌的EMG峰值活动高于咬肌，并且在咬肌中，深层咬肌的EMG峰值高于浅层咬肌。与此相反，在开口/闭口运动中，咬肌的峰值活动高于颞肌，而浅层咬肌的EMG峰值活动高于深层咬肌。在深层咬肌内也发现了差异。在开口/闭口运动中，前部深层区域的EMG峰值活动高于后部区域，而在前伸/后缩运动和侧方偏斜过程中，后部深层区域的峰值更高。一般来说，速度对EMG峰值活动的影响大于外部负荷。仅在侧方偏斜过程中，速度和负荷对深层和浅层咬肌的峰值活动影响相同。在前伸/后缩运动中，负荷对咬肌的EMG峰值活动没有显著影响。一个普遍的发现是，根据任务不同，不同区域会优先被激活。这表明运动神经元池的兴奋性指令存在分区。
