Faculty of Sport Sciences, Waseda University, Tokorozawa, Saitama, Japan.
Department of Anatomy, Aichi Medical University, Nagakute, Aichi, Japan.
PLoS One. 2019 Feb 8;14(2):e0211485. doi: 10.1371/journal.pone.0211485. eCollection 2019.
The human triceps surae (two gastrocnemii and soleus) has aponeuroses in the proximal and distal aspects, the latter of which insert into the calcaneus by sharing the common Achilles tendon. These tendinous tissues are known to have elasticity and upon muscle contraction the aponeurosis is stretched both longitudinally (along the muscle's line of action) and transversely. Higher aponeurosis transverse deformability has been documented, but there is a paucity of information on the morphology and mechanical properties of human aponeurosis. This study aimed to identify morphological and mechanical characteristics of the human triceps surae aponeuroses. Twenty-five triceps surae muscle-tendon units were procured from 13 human donors (formalin fixed, 6 males, 7 females) aged 67-91 years. Specimens of aponeuroses were excised from the eight regions (posterior and anterior regions of the gastrocnemius medialis and lateralis, medial and lateral parts of soleus; proximal, middle, and distal sites each, 2-4 cm × 2-4 cm). Aponeurosis thickness was measured using a digital caliper. Uniaxial tensile tests were implemented to determine the mechanical properties of specimens loaded longitudinally (along the muscle's line of action) and transversely. The aponeurosis thickness showed significant differences between muscles and sites, while Young's modulus showed direction-dependent (longitudinal vs. transverse) differences within sites. Results show different morphology and mechanical properties of aponeuroses between synergist muscles. The reason for site-dependent differences in stiffness is due to a reduced aponeurosis thickness rather than a reduction in the material property. The anisotropic elastic feature (differences between longitudinal and transverse directions) of the aponeuroses was more pronounced than previous in vivo findings, suggesting inherent material design of the aponeurosis that matches three-dimensional contractile behavior of muscle fibers.
人类小腿三头肌（两块比目鱼肌和腓肠肌）在近端和远端都有腱膜，后者通过共享共同的跟腱插入跟骨。这些腱组织具有弹性，在肌肉收缩时，腱膜会沿着肌肉的作用线纵向拉伸，同时也会横向拉伸。已经有研究记录了较高的腱膜横向可变形性，但关于人类腱膜的形态和力学特性的信息却很少。本研究旨在确定人类小腿三头肌腱膜的形态和力学特征。从 13 名年龄在 67-91 岁的人类供体中获得了 25 个小腿三头肌肌腱-肌腹单位（福尔马林固定，6 名男性，7 名女性）。从内侧和外侧比目鱼肌的后区和前区、比目鱼肌的内侧和外侧部分、每块肌肉的近端、中间和远端（每个 2-4cm×2-4cm）切除腱膜标本。使用数字卡尺测量腱膜厚度。对标本进行单轴拉伸试验，以确定沿肌肉作用线纵向加载和横向加载时的力学性能。腱膜厚度在肌肉和部位之间存在显著差异，而杨氏模量在部位内显示出与方向相关的（纵向与横向）差异。结果表明，协同肌之间的腱膜具有不同的形态和力学特性。刚度部位依赖性差异的原因是腱膜厚度减小，而不是材料性能降低。腱膜的各向异性弹性特征（纵向和横向之间的差异）比以前的体内研究结果更为明显，这表明腱膜具有内在的材料设计，与肌肉纤维的三维收缩行为相匹配。
