Functional, anatomical, and neurophysiological study of human upper limb muscles

1.手肘屈肌的功能和解剖学研究：在健康人受试者中，通过电激活两个肘屈肌（肱二头肌：BB，肱桡肌：BR）来检查前臂旋后。肌肉分别激活通过导线电极与计算机控制的多通道刺激器的电刺激。激活BB诱导的屈曲和旋后，激活BR诱导的屈曲。在适当的刺激强度下激活BR，可在保持前臂俯卧的情况下保持肘部。在这种情况下，BB的额外激活伴随着BR的刺激强度的降低导致旋后而不屈曲。由于肱三头肌在整个运动过程中没有收缩，这支持了一种理论，即屈肌之间的代偿性活动变化允许BB在没有屈曲的情况下进行旋后运动。2.手肘关节周围肌肉的神经生理学研究：肱二头肌（BB），肱桡肌（BR），用自发激活运动单位的刺激后时间直方图法研究了人的旋前圆肌（PT）。对BB、BR和PT神经的电条件刺激分别导致BR和PT、BB和PT以及BB的运动单位的抑制。在远低于运动阈值的刺激强度下诱导抑制。抑制的潜伏期比同向易化的潜伏期长0- 2 ms。提示BB与BR、BB与PT、BR与PR之间均存在抑制性投射，这种抑制作用是通过I类传入和寡（二或三）突触连接介导的。

1.Functional and anatomical studies of the elbow flexors.Forearm supination produced by electrical activation of two elbow flexors (biceps brachii : BB,brachioradialis : BR) was examined in healthy human subjests. The muscles were activated separately by electrical stimulation through wire electrodes with a computer-controlled multi-channel stimulator. Activation of BB induced flexion and supination and that of BR induced flexion. Activation of BR with adequate stimulation intensity provided holding of elbow with maintaining the forearm prone. In this situation, additional activation of BB accompanied with a decrease of stimulation intensity for BR resulted in supination without flexion. Since the triceps brachii showed no contraction throughout the motion, it supports a theory that compensatory changes of activities among the flexors permit BB to work for supination without flexion.2.Neurophysiological studies of the muscles crossing the elbow joint.Neural projections among the biceps brachii (BB), brachioradialis (BR), and pronator teres (PT) in humans were studied using the method of post-stimulus time histograms of voluntarily activated motor units. Electrical conditioning stimuli to the BB,BR and PT nerves resulted in inhibition in motor units of BR and PT,of BB and PT,and of BB,respectively. The inhibition was induced with the stimulation intensity well below the motor threshold. The latency of the inhibition was 0-2ms longer than that of the homonymous facilitation. These findings suggest that inhibitiory projections between BB and BR,and between BB and PT,and from BR to PR exist and the inhibition is mediated through group I afferents and oligo (di or tri) -synaptic linkage.