EMG Study of the Lateral Pterygoid Muscles on Isometric Horizontal Mandibular Forces

实验一研究了6名男性受试者在三种不同肌长下，缩短翼外肌下头（ILPT）对等长伸展和外侧伸展收缩时眼震电图（ENG）功率谱的影响，在所有肌长下，两侧ILPT等长伸展收缩时眼震电图（ENG）功率谱的平均频率无显著性差异。这一结果与不同颌位等长张口时的二腹肌相似，而与不同颌位等长紧咬时的颞肌和咬肌不同。实验2咬肌、颞后肌、研究了6 - 24名正常成人在等长收缩期间的二腹肌前肌和翼外肌，在不同的力量水平和不同的肌肉长度下。在四块肌肉中，在不同的力水平下，ENG振幅与频率成反比。而在不同肌长时，咬肌和颞肌的频率与振幅的关系呈正比，二腹肌和翼肌肌电之间呈负相关，推测这种肌长不同时的平均频率变化和频率与振幅之间的相关性是包括下外侧肌在内的降颌肌肌电的特征翼肌

Experiment 1Six male subjects were studied to determine the effect on the ENG power spectra of shortening the inferior head of the lateral pterygoid muscle (ILPT) during isometric protrusive and lateral protrusive contraction at three different muscle lengths.Among all muscle lengths, no significant difference in mean frequency of ENG power spectra was seen on either side of the ILPT during isometric protrusive contraction. This result is similar to that for the digastric muscle during isometric under opening at various jaw positions, but differs from those for the temporal and masseter muscles at during isometric clenching at various jaw positions.Experiment 2The relation between frequency and amplitude on electromyograph of masseter, posterior temporal, anterior digastric and lateral pterygoid muscles on six to twenty-four normal human adults were studied during isometric contractions, at different force levels and at different muscle lengths. ENG amplitude was inversely proportional to frequency at different force levels in four muscles. However, at different muscle length, the direct proportion was shown the relation between frequency and amplitude in the masseter and temporal muscles, but there were inversely correlations between them in the digastric and pterygoid muscles.It was speculated that this lack of significant mean frequency change and correlation between frequency and amplitude at different muscle lengths is characteristic of the EMGs of jaw depressor muscles including inferior lateral pterygoid muscle.