Physiological Analysis of Correlation Between Rhythmical Jaw Movements and Monosynaptic Spinal Reflex in Humans

我们以前报道过人类比目鱼h反射（S.H-R）在咬牙过程中显著促进，并且促进程度随着咬牙力的增加而增加。在这项研究中，我们研究了在无牙齿接触的有节奏的下颌运动（RJMs）和有节奏的口香糖咀嚼（RGC）中s.h.r是否有任何调节。实验对象为5名无口颌功能障碍的男性志愿者（年龄22-27岁）。受试者坐在躺椅上。双腿分别用大约120和100进行膝关节和踝关节的固定。同时记录右侧比目鱼肌、咬肌和双侧二腹肌前肌的表面肌电图。采用电刺激腘窝胫神经引起s.h.r。受试者自行完成RJMs和RGC。比较了下颌运动时与保持下颌静止状态时的s.h.r峰间振幅。我们发现(1)在rms和RGC期间S.H-R被促进（P<0.05， t检验），(2)咬肌活动时和前二腹肌活动时的促进程度无显著差异（P<0.05，方差分析）。结果表明：(1)人比目鱼单突触反射在咀嚼过程中具有紧张性促进作用，(2)口内机械感受器的传入脉冲对促进作用并不是必不可少的。一般认为口腔运动活动对身体运动功能有很强的影响。

We previously reported that human soleus H-reflex (S.H-R) was remarkably facilitated during teeth clenching, and that the magnitude of the facilitation increased with teeth clenching force. In this study, we investigated whether there was any modulation of S.H-R during rhythmical jaw movements with no teeth contacts (RJMs) and rhythmical gum chewing (RGC) . Experiments were carried out in 5 male volunteers (age : 22-27 years) with no stomatognathic dysfunction. The subjects were seated in a reclining armchair. Both legs were fixed with the knee and ankle joints at approximately 120ﾟ and 100ﾟ, respectively. Surface EMG was simultaneously recorded from the right soleus musle as well as the masseter and the anterior digastric muscles bilaterally. Electrical stimulation was applied to the tibial nerve at the popliteal fossa to elicit S.H-R. The subject performed self-paced RJMs and RGC.The peak-to-peak amplitude of the S.H-R during jaw movements was compared with that during maintaining the jaw at rest position. We found that (1) S.H-R was facilitated during RJMs and RGC (P<0.05, t-test) , and (2) there was no significant difference in the magnitude of the facilitation between the phase when the masseter muscle was active and that when the anterior digastric muscle was active (P>0.05, ANOVA) . It was concluded that (1) human soleus monosynaptic reflex is tonically facilitated during mastication, and (2) afferent impulses from intraoral mechanoreceptors are not indispensable for the facilitation. It is assumed that the oral motor activity exerts a strong influence on the bodily motor function in general.