Griffiths R I
Department of Medical Physiology, University of Calgary, Alta., Canada.
J Neurosci Methods. 1987 Oct;21(2-4):159-65. doi: 10.1016/0165-0270(87)90113-0.
The movement occurring in whole muscle during contraction is divided between the muscle fibres, the tendon and the longitudinal change in length due to a change in pennation angle. The relative importance of each of these components varies between muscles and with how they are being used. To date it has not been possible to measure each of these movements. By suturing piezoelectric crystals to each end of a small group of muscle fibres in cat medial gastrocnemius muscle, the transit time of ultrasound between the crystals was measured. Assuming a constant velocity of sound in muscle of 1580 m/s, the transit time was used to calculate the muscle fibre length. In "isometric" tetanic contractions the muscle fibres shortened by up to 25% at the expense of the tendons. Lengthening the muscle by 4 mm between each two tetanii, produced less than 4 mm stretch of the muscle fibres as some of the movement was taken up by a change in pennation angle. Except at long lengths, when passive tensions were present, none of this movement between tetanii could be accounted for by stretch of the tendon.
肌肉收缩时整块肌肉发生的运动，在肌纤维、肌腱以及由于羽状角变化导致的长度纵向改变之间进行分配。这些组成部分各自的相对重要性因肌肉不同以及肌肉的使用方式而异。到目前为止，还无法测量这些运动中的每一项。通过将压电晶体缝合到猫内侧腓肠肌一小群肌纤维的两端，测量了晶体之间超声波的传播时间。假设肌肉中声音的速度恒定为1580米/秒，传播时间用于计算肌纤维长度。在“等长”强直收缩中，肌纤维缩短多达25%，代价是肌腱。在每两次强直收缩之间将肌肉拉长4毫米，由于一些运动被羽状角的变化所吸收，肌纤维的拉伸小于4毫米。除了在存在被动张力的长长度情况下，两次强直收缩之间的这种运动都不能用肌腱的拉伸来解释。
