Thixotropic behaviour of human finger flexor muscles with accompanying changes in spindle and reflex responses to stretch.
Thixotropic behaviour of human finger flexor muscles with accompanying changes in spindle and reflex responses to stretch.
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人类手指屈肌的触变行为伴随着纺锤体的变化和对拉伸的反射反应。
DOI：
10.1113/jphysiol.1985.sp015860
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发表时间：
1985
期刊：
影响因子：
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通讯作者：
E. U. Wallin
中科院分区：
文献类型：
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作者：
K. Hagbarth;J. Hägglund;M. Nordin;E. U. Wallin
根据先前关于肌肉触变的报道，我们研究了人类受试者在休息时手指屈肌固有和反射刚度的变化，在涉及手指屈肌收缩和/或长度变化的短暂调节操作之后。刚度测量与前臂和手部肌肉的肌电记录以及手指屈神经束传入拉伸反应的微神经图记录相结合。通过测量(a)掌指关节的屈曲角度来评估手指屈曲刚度，系统在休息时平衡重力，(b)由转矩电机传递的恒定强度的周期性伸伸扭矩脉冲引起的手指角度伸伸的速度和幅度。在后一种情况下，手指在静止位置的延伸漂移可以通过弱弯曲偏置扭矩来防止，将手指保持在预定的半弯曲位置，反对停止杆。研究了在前臂和手部肌肉神经阻滞或神经病变阻止神经介导收缩的受试者中，被动大幅度手指屈伸后僵硬度的变化。固有刚度增强后瞬态手指屈曲和减少后瞬态手指延伸。在几分钟的观察期间，后效逐渐减弱。同样的结果也出现在神经支配完整的受试者身上，他们在训练前和训练后成功地保持了手臂和手部肌肉的放松（即没有肌电图活动）。在这些研究对象中，研究人员还发现，主动和被动手指运动的后续效应是相似的，而且等距主动手指屈肌收缩以类似于手指伸展的方式放松了系统。在一些受试者中，手指屈肌出现肌电反射放电，以响应伸展试验脉冲。当被恒定振幅的小斜坡拉伸刺激引起时，拉伸反射反应的强度变化与各种调节动作后固有刚度的变化平行。肌神经中多单元传入牵张放电的强度，作为肌纺锤体牵张敏感性的指标，与固有刚度的变化平行变化。当记录部位近端神经阻滞使纺锤体去传出时，也可以观察到肌肉纺锤体拉伸敏感性的操纵后变化。结果可以解释为触变行为的条款外-和-内肌纤维。（摘要删节为400字）
Prompted by previous reports on muscle thixotropy, we have investigated changes in inherent and reflex stiffness of the finger flexor muscles of human subjects at rest, following transient conditioning manoeuvres involving contractions and/or length changes of the finger flexors. The stiffness measurements were combined with electromyographic recordings from forearm and hand muscles and with microneurographic recordings of afferent stretch responses in finger flexor nerve fascicles. Finger flexor stiffness was evaluated by measuring (a) the flexion angle of the metacarpo‐phalangeal joints at which the system during rest balanced the force of gravity and (b) the speed and amplitude of angular finger extensions induced by recurrent extension torque pulses of constant strength delivered by a torque motor. In the latter case, extension drifts in the resting position of the fingers were prevented by a weak flexion bias torque holding the fingers in a pre‐determined, semiflexed position against a stop‐bar. Stiffness changes following passive large amplitude finger flexions and extensions were studied in subjects with nerve blocks or nerve lesions preventing neurally mediated contractions in the forearm and hand muscles. Inherent stiffness was enhanced following transient finger flexions and reduced following transient finger extensions. The after‐effects gradually declined during observation periods of several minutes. Similar results were obtained in subjects with intact innervation who succeeded during the pre‐ and post‐conditioning periods in keeping the arm and hand muscles relaxed (i.e. showed no electromyographic activity). In these subjects it was also found that the after‐effects were similar for active and passive finger movements and that isometric voluntary finger flexor contractions loosened the system in a way similar to finger extensions. In some subjects electromyographic reflex discharges appeared in the finger flexors in response to the extension test pulses. When elicited by small ramp stretch stimuli of constant amplitude, the stretch reflex responses were found to vary in strength in parallel with the changes in inherent stiffness following the various conditioning manoeuvres. The strength of the multi‐unit afferent stretch discharges in the muscle nerve, used as index of muscle spindle stretch sensitivity, varied in parallel with the changes in inherent stiffness. Post‐manoeuvre changes in muscle spindle stretch sensitivity were seen also when the spindles were de‐efferented by a nerve block proximal to the recording site. The results can be explained in terms of thixotropic behaviour of extra‐ and intrafusal muscle fibres.(ABSTRACT TRUNCATED AT 400 WORDS)