A role of muscle spindle afferents in the control of masticatory jaw movements.

研究了肌梭末梢在控制咀嚼运动和闭口肌活动中的作用：1)损毁肌梭传入神经节细胞所在的三叉神经中脑核(MES V)对咬肌肌电活动的影响；2)分析咀嚼试片时MES V神经元的活动。研究结果如下：1)咀嚼测试条时的咀嚼肌电活动显著降低；2)在张口期和咬合期开始时都被兴奋的MES V单位，在咀嚼测试条时增加了它们的放电频率。它们对琥珀胆碱敏感，可能是主要的纺锤体传入。根据这些结果，我们得出结论，在咀嚼周期的咬合阶段，闭口肌(可能是初级末端)的肌梭有助于增强闭口肌的活动，从而增加颌骨的内侧偏转。

Contribution of muscle spindle endings to the control of masticatory jaw-movements and jaw-closing muscle activities was studies 1) by examining the effects of making a lesion of the trigeminal mesencephalic nucleus (Mes V), in which ganglion cells of muscle spindle afferents locate, on EMG activities of the masseter muscle, and 2) by analysing activities of the Mes V neurons during chewing a test strip. The results are as follows : 1) the masseteric EMG activities during chewing a test strip were significantly reduced by lesioning the Mes V; 2) the Mes V units, which were excited at the beginning of both the jaw-opening and occlusion pheses, increased their firing frequency during chewing a test strip. They were sensitive to suxamethonium administration and supposed to be the primary spindle afferents. Based on these results, we conclude that the muscle spindles of jaw-closing muscles (presumably primary endings) contribute to the enhancement of jaw-closing muscle activities and thus increased the medial excursing of the jaw during the occlusion phase of a masticatory cycle.