Di Lazzaro V, Quartarone A, Higuchi K, Rothwell J C
Istituto di Neurologia, Universita, Cattolica, Rome Italy.
Exp Brain Res. 1995;102(3):474-82. doi: 10.1007/BF00230651.
We describe a reflex evoked in neck muscles by stimulation of afferent fibres in the trigeminal nerve. The clearest responses were seen in averaged, unrectified, monopolar surface electromyographic (EMG) recordings from active sternocleidomastoid muscles after stimulation of the infraorbital nerve. They consisted of a bilateral positive/negative (p19, n31) wave with a mean onset latency of 12.9 ms which corresponded to a period of inhibition in the underlying motor unit activity. Responses also could be seen in splenius and trapezius, but not in arm muscles. Stimuli to other branches of the trigeminal nerve (supraorbital or mental) did not produce such clear effects. The threshold for the reflex was relatively low (2-4 times perceptual threshold) and its size scaled with the level of background EMG in an approximately linear fashion. Responses to infraorbital stimulation did not interact with other short-latency inhibitory responses in the sternocleidomastoid muscle evoked by loud acoustic clicks or stimulation of the median nerve at the wrist. We suggest that the infraorbital response is part of a head withdrawal reflex involving an oligosynaptic trigemino-cervical system similar to that described in the cat.
我们描述了一种通过刺激三叉神经传入纤维在颈部肌肉中诱发的反射。在刺激眶下神经后，在活跃的胸锁乳突肌的平均、未整流、单极表面肌电图（EMG）记录中观察到最清晰的反应。它们由一个双侧正/负（p19，n31）波组成，平均起始潜伏期为12.9毫秒，这与基础运动单位活动的抑制期相对应。在斜方肌和菱形肌中也能看到反应，但在手臂肌肉中则看不到。刺激三叉神经的其他分支（眶上或颏神经）不会产生如此明显的效果。该反射的阈值相对较低（为感觉阈值的2 - 4倍），其大小与背景EMG水平大致呈线性关系。对眶下刺激的反应与由大声点击或手腕处正中神经刺激诱发的胸锁乳突肌中的其他短潜伏期抑制反应没有相互作用。我们认为眶下反应是一种头部退缩反射的一部分，涉及一个类似于猫中描述的少突触三叉神经 - 颈系统。
