[Facilitation of tibialis anterior H reflex and depression of reciprocal Ia inhibition on soleus motoneurons during teeth-clenching in man].
Modulation of the tibialis anterior (T.A.) H reflex and the reciprocal Ia inhibition from the ankle flexor to the extensor were studied during voluntary teeth-clenching in 7 healthy adult volunteers to investigate the correlation between the oral motor activity and the somatic motor function. The T.A. H reflex was significantly facilitated during voluntary teeth-clenching, and the amount of this facilitation increased with the level of masseter EMG activity. Furthermore, the reciprocal Ia inhibition of the soleus H reflex, induced by stimulation of the common peroneal nerve at a subthreshold intensity for evoking the T.A. M wave, was significantly depressed during voluntary teeth-clenching. It was concluded that 1) the T.A. H reflex is facilitated during voluntary teeth-clenching, 2) there is a positive correlation between the amount of facilitation of the T.A. H reflex and the level of teeth-clenching force, and 3) the reciprocal Ia inhibition of the crural muscle is reduced during voluntary teeth-clenching. It was suggested that teeth-clenching contributes to stability of body stance by increasing the stiffness of the ankle joint.
Takada
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Department of Maxillo-Facial Prosthetics, Life Science of Maxillo-Facial Systems, Tokyo Medical and Dental University.
D000328:Adult; D004594:Electrophysiology; D006801:Humans; D007568:Jaw / Q000502:physiology; D007866:Leg / Q000502:physiology*; D008297:Male; D008410:Masticatory Muscles / Q000502:physiology*; D009046:Motor Neurons / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology*; D012018:Reflex / Q000502:physiology*