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

实验16以16名男性受试者为研究对象，研究了缩短翼外肌下头在三种不同肌肉长度的等距收缩和侧突收缩过程中对ENG功率谱的影响。在所有肌肉长度中，在等距突出收缩期间，ILPT两侧的ENG功率谱平均频率无显着差异。这一结果与二腹肌在不同颌位张紧时的结果相似，但与颞肌和咬肌在不同颌位张紧时的结果不同。实验二：研究了6 ~ 24例正常人在不同强度、不同长度肌肉收缩时咬肌、颞后肌、二腹肌前肌和翼状外侧肌的肌电图频率与振幅的关系。在不同的力水平下，四个肌肉的ENG振幅与频率成反比。而在不同肌长下，咬肌和颞肌的频率与振幅呈正比关系，而二腹肌和翼状肌的频率与振幅呈负相关关系。我们推测，在不同肌肉长度处缺乏显著的平均频率变化以及频率和振幅之间的相关性是包括下外侧翼状肌在内的下颌降肌肌电图的特征。

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.