Cadden S W, Newton J P
Department of Dental Prosthetics and Gerontology, Dental School, University of Dundee, U.K.
Arch Oral Biol. 1994 Jun;39(6):473-80. doi: 10.1016/0003-9969(94)90143-0.
Electromyographic recordings (EMGs) were made from the active masseter muscle of the inhibitory reflex evoked by application of electrical stimuli to the skin of the upper lip in 11 human subjects. In control sequences, the reflex had a mean latency and duration of 41 +/- 1.7 and 44 +/- 2.6 ms, respectively. The magnitude of the reflex (measured by integration of the EMG) was significantly reduced by the application of cold (3 degrees C) or hot (47-48 degrees C) but not warm (38-46 degrees C) water to a hand or foot. The strongest stimuli (3 or 48 degrees C) produced mean reductions of the reflex magnitude in the range of 62-85%. These effects occurred regardless of whether the background activity in the masseter was raised or lowered during the application of the thermal stimuli. Thus, activity in nociceptive nerves from widespread areas of the body can modulate jaw reflexes in man by exerting an influence on the reflex pathway at a point before the motor neurones. This may involve the system of 'diffuse noxious inhibitory controls', which have been shown to depress limb flexion reflexes and neuronal activity in the spinal dorsal horn and trigeminal nuclear complex.
对11名受试者，通过对上唇皮肤施加电刺激诱发抑制性反射，记录主动咬肌的肌电图（EMG）。在对照序列中，该反射的平均潜伏期和持续时间分别为41±1.7毫秒和44±2.6毫秒。通过对手或脚施加冷水（3℃）或热水（47 - 48℃）而非温水（38 - 46℃），反射幅度（通过EMG积分测量）显著降低。最强刺激（3℃或48℃）使反射幅度平均降低62 - 85%。无论在施加热刺激期间咬肌的背景活动是升高还是降低，这些效应都会出现。因此，来自身体广泛区域的伤害性神经活动可通过在运动神经元之前的一点对反射通路施加影响，来调节人类的下颌反射。这可能涉及“弥漫性伤害性抑制控制”系统已被证明可抑制肢体屈曲反射以及脊髓背角和三叉神经核复合体中的神经元活动。
