Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada.
J Appl Physiol (1985). 2013 Jul 1;115(1):116-25. doi: 10.1152/japplphysiol.01090.2012. Epub 2013 May 2.
The aim of this study was to determine the three-dimensional (3D) muscle fascicle architecture in human triceps surae muscles at different contraction levels and muscle lengths. Six male subjects were tested for three contraction levels (0, 30, and 60% of maximal voluntary contraction) and four ankle angles (-15, 0, 15, and 30° of plantar flexion), and the muscles were imaged with B-mode ultrasound coupled to 3D position sensors. 3D fascicle orientations were represented in terms of pennation angle relative to the major axis of the muscle and azimuthal angle (a new architectural parameter introduced in this study representing the radial angle around the major axis). 3D orientations of the fascicles, and the sheets along which they lie, were regionalized in all the three muscles (medial and lateral gastrocnemius and the soleus) and changed significantly with contraction level and ankle angle. Changes in the azimuthal angle were of similar magnitude to the changes in pennation angle. The 3D information was used for an error analysis to determine the errors in predictions of pennation that would occur in purely two-dimensional studies. A comparison was made for assessing pennation in the same plane for different contraction levels, or for adjusting the scanning plane orientation for different contractions: there was no significant difference between the two simulated scanning conditions for the gastrocnemii; however, a significant difference of 4.5° was obtained for the soleus. Correct probe orientation is thus more critical during estimations of pennation for the soleus than the gastrocnemii due to its more complex fascicle arrangement.
本研究旨在确定不同收缩水平和肌肉长度下人类比目鱼肌的三维（3D）肌束结构。6 名男性受试者分别在 3 个收缩水平（0%、30%和 60%最大自主收缩）和 4 个踝关节角度（-15°、0°、15°和 30°跖屈）下进行测试，并使用 B 型超声与 3D 位置传感器相结合对肌肉进行成像。3D 肌束方向以相对于肌肉主轴的羽状角和方位角（本研究中引入的新结构参数，代表围绕主轴的径向角）来表示。肌束和它们所在的肌片的 3D 方向在所有 3 块肌肉（内侧和外侧腓肠肌和比目鱼肌）中进行了区域化，并随着收缩水平和踝关节角度的变化而显著变化。方位角的变化与羽状角的变化大小相当。3D 信息用于误差分析，以确定在纯二维研究中预测羽状角时会出现的误差。比较了用于评估不同收缩水平下同一平面内羽状角的方法，或用于调整不同收缩水平下扫描平面方向的方法：对于腓肠肌，两种模拟扫描条件之间没有显著差异；然而，对于比目鱼肌，获得了 4.5°的显著差异。因此，由于其更复杂的肌束排列，在估计比目鱼肌的羽状角时，探头的正确方向比对腓肠肌更关键。
