Naito A, Sun Y J, Yajima M, Fukamachi H, Ushikoshi K
Department of Anatomy, Shinshu University School of Medicine, Matsumoto, Japan.
Tohoku J Exp Med. 1998 Dec;186(4):267-77. doi: 10.1620/tjem.186.267.
Activities of the elbow flexors (biceps brachii, BB; brachialis, B; brachioradialis, BR) and extensors (triceps brachii, TB) in a motion of forearm pronation/supination with maintenance of elbow flexion (PS-movement) in nine healthy human subjects were studied by electromyography (EMG). The subject performed the PS-movement slowly or quickly with or without a load extending the elbow. In the slow PS-movement, an increase and decrease of EMG activities during supination and pronation, respectively, were seen in BB and the reverse was in B. A clear increment of EMG activities in BB accompanied with a reduction of EMG activities in B and/or BR, and the reverse were often observed. The contraction level and gain with the forearm supine were higher and larger than those with the forearm prone, respectively, in BB and the reverse was in B and BR. In a series of the quick PS-movement, alternating increases of EMG activities between BB and the other flexors (B and BR) were seen. Since TB showed no EMG activities throughout the experiment, it is suggested that reciprocal contractions between BB and the other flexors, which produce a complementary force in flexion direction, enable motions of pronation/supination with maintenance of flexion. Contraction properties of the flexors were discussed.
通过肌电图（EMG）研究了9名健康受试者在保持肘部屈曲的前臂旋前/旋后运动（PS运动）中肘部屈肌（肱二头肌，BB；肱肌，B；肱桡肌，BR）和伸肌（肱三头肌，TB）的活动情况。受试者在有或没有伸展肘部的负荷情况下，缓慢或快速地进行PS运动。在缓慢的PS运动中，BB在旋后和旋前过程中肌电活动分别增加和减少，而B则相反。经常观察到BB的肌电活动明显增加，同时B和/或BR的肌电活动减少，反之亦然。在BB中，前臂仰卧位时的收缩水平和增益分别高于前臂俯卧位时，而在B和BR中则相反。在一系列快速PS运动中，BB与其他屈肌（B和BR）之间的肌电活动交替增加。由于在整个实验过程中TB均未显示肌电活动，因此表明BB与其他屈肌之间的相互收缩在屈曲方向上产生互补力，从而实现了在保持屈曲的情况下进行旋前/旋后运动。讨论了屈肌的收缩特性。
