STRETCH REFLEX AND SERVO ACTION IN A VARIETY OF HUMAN MUSCLES
STRETCH REFLEX AND SERVO ACTION IN A VARIETY OF HUMAN MUSCLES
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DOI：
10.1113/jphysiol.1976.sp011481
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发表时间：
1976-01-01
影响因子：
5.5
通讯作者：
MORTON, HB
中科院分区：
文献类型：
--
作者：
MARSDEN, CD;MERTON, PA;MORTON, HB
在拇指长屈肌中，牵张反射和其他伺服动作表现的潜伏期约为45 ms，大约是手指抖动潜伏期的两倍。在拇指的长屈肌中，肌腱痉挛是微弱的或不存在的，即使在这个肌肉中具有活跃的长潜伏期拉伸反射的受试者中也是如此。腱反射的神经机制可能与牵张反射不同。一个肌肉有微弱的肌腱抽搐可能会显示一个迟发成分的反应，肌腱轻拍，与潜伏期类似的长潜伏期牵张反射。假设牵张反射的潜伏期超过腱反射的潜伏期是因为牵张反射采用皮质而不是脊弧，那么对于大脚趾的长屈肌，预期的超额幅度较大，而对于下颌闭合肌，则较小。这一点得到了证实。另一种假设认为，拇指和脚趾的伸展反射的长潜伏期是因为它们被慢传导传入神经兴奋，这一假设是不可能的，因为在近端手臂肌肉中也发现了具有相等或更大额外潜伏期的伸展反射。近端肌肉的长潜伏期牵张反射在一个健康的受试者身上表现得最为明显，而这个受试者恰好有微弱或缺失的肌腱痉挛。在普通受试者中，近端肌肉的牵张反射通常有一个大的、短潜伏期的、可能是脊髓的成分;也可以看到对停止和释放的短潜伏期反应。这种脊髓潜伏期伺服动作在近端肌肉中的意义仍有待探讨。现有的数据和从大脑皮层的传导时间是兼容的假设，即长潜伏期成分的牵张反射使用经皮层反射弧，本论文中描述的实验都没有对这一观点产生不利影响。
In the long flexor of the thumb the latency of the stretch reflex and of other manifestations of servo action was some 45 ms, roughly double the latency of a finger jerk. Tendon jerks were feeble or absent in the long flexor of the thumb, even in subjects with brisk long-latency stretch reflexes in this muscle. The nervous mechanism of the tendon jerk may be different from that of the stretch reflex. A muscle that has feeble tendon jerks may show a late component in the response to a tendon tap, with a latency similar to that of the long-latency stretch reflex. On the hypothesis that the excess latency of the stretch reflex over that of a tendon jerk is because the stretch reflex employs a cortical rather than a spinal arc, the excess would be expected to be larger in magnitude for the long flexor of the big toe and smaller for the jaw closing muscles. This was confirmed. An alternative hypothesis that the long latency of stretch reflexes in thumb and toe is because they are excited by slow-conducting afferents was made improbable by the finding that stretch reflexes with an equal or greater excess latency are also found in proximal arm muscles. The long-latency stretch reflex in proximal muscles was seen most distinctly in a healthy subject who happened to have feeble or absent tendon jerks. In ordinary subjects there was often a large, short-latency, presumably spinal component of the stretch reflex in proximal muscles; and short-latency responses to halt and release were also seen. The significance of this spinal latency servo action in proximal muscles remains to be explored. The available data on conduction time to and from the cerebral cortex are compatible with the hypothesis that the long-latency component of the stretch reflex uses a transcortical reflex arc, and none of the experiments described in the present paper are inimical to this view.