Question

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Muscle-tendon structure and dimensions in adults and children.
成人与儿童肌腱的结构和大小
Abstract
Muscle performance is closely related to the architecture and dimensions of the muscle-tendon unit and the effect of maturation on these architectural characteristics in humans is currently unknown. This study determined whether there are differences in musculo-tendinous architecture between adults and children of both sexes. Fascicle length and pennation angle 肌纤维与肌腱所成角度 were measures from ultrasound images at three sites along the length of the vastus intermedius, vastus lateralis, vastis medialis and rectus femoris muscles. Muscle volume and muscle-tendon length were measured from magnetic resonance images. Muscle physiological cross-sectional area (PCSA) was calculated as the ratio of muscle volume to optimum fascicle length. Fascicle length was greater in the adult groups than in children but pennation angle did not differ between groups between adults and children for any quadriceps muscle. Quadriceps volume and PCSA of each muscle were greater in adults than children but the relative proportion of each head to the total quadriceps volume was similar in all groups. However, the difference in PCSA between adult and children was greater than the difference in fascicle length. It is concluded that the fascicle, muscle and tendon lengthen proportionally during maturation, thus the muscle-tendon stiffness and excursion range are likely to be similar in children and adults but the relatively greater increase in PCSA than fascicle length indicates that adult muscles are better designed for force production than children’s muscles.
Muscle and tendon length
The length of each quadriceps femoris head muscle was measured from the MRIs. The proximal tendon and its origin could not be clearly identified from the MRIs for any of the muscles. Therefore, the tendon length for each muscle was calculated as the difference between length of the entire MTU and muscle length. The length of MTU was estimated based on the distance between the bony landmarks typically considered as the origin and insertion of each muscle. The origins of the VI, VL and VM muscles extend along the linea aspera, with the most proximal attachment point being at the level of the greater trochanter, which we considered to be the origin of these three muscles. The RF MTU originates at the anterior inferior iliac spine. The insertion of the MTU of all muscles was the superior border of the patella. These landmarks were identified from the MRIs and the distance between them considered as the length of the respective MTU.
Maximal voluntary contraction. Isometric plantar flexion and dorsiflexion maximal voluntary contraction (MVC) torque was recorded while the subject was prone with the knees fully extended and the tested foot (left foot) strapped to the footplate of a dynamometer. The plantar flexion MVCs were used to assess muscle strength, whereas dorsiflexion MVCs were used to quantify antagonistic muscle coactivation and enable the assessment of gastrocnemius (GS) tendon mechanical properties (see below). To emulate the ankle joint angle during the postural tests, all MVC measurements were taken at 0° ankle angle (the foot at 90° with respect to the lower leg axis). The subjects were asked to gradually develop torque and maintain MVC for 3 s. A short series of three to four warm-up submaximal contractions were carried out at the beginning of the protocol. During all tests, visual and verbal feedback was employed to motivate the subjects.

Answer 1

摘要
肌肉要完成各种动作，同肌腱单元的结构和大小息息相关，然而在人体内，这种成熟性在这些肌腱的结构特性上所造成的影响仍然有待进一步探索。这项研究断定了成年人与儿童是否在肌腱单位构造上存在差异。肌纤维与肌腱所成角度是通过运用彩超技术来测量股中间肌、股外侧肌、股内侧肌和股直肌三部分(你最好再检查一下，原文是不是three sites)所成角度的。肌肉体积大小和肌腱长度则是利用磁共振图像来完成测量的。肌肉的生理横切断面大小则是由肌肉体积同肌束最优长度的比值来表示的。成年人体内的肌束比儿童的长，但两组人群的四头肌在pennation（麻烦你再看一下吧，我能想到的字典都翻遍了找不到pennation这个东西）所能成角度方面基本不存在差异。成年人每块肌肉的四头肌体积和横断切面比儿童大，但两组数据的相关比值以及总比比值却是十分相似，然而成年人与儿童在肌肉横断切面的差异却又比在肌束长度上更明显。由此我们可以得出结论：肌束、肌肉与肌腱随着人体逐渐成熟而相应伸长，那么成年人的肌肉僵直与冲程（偏移、移动都可）范围与儿童则很有可能相似，但是横断切面相应地伸长，甚至长过肌束长度就暗示了成年人的肌肉要比儿童的肌肉更有力量。

肌肉与肌腱长度
每块股四头肌的长度都是通过核磁共振技术测量出的。但是任何一块肌肉的近端腱和它的发出点却不能通过核磁共振技术精确定位。因此，每块肌肉的肌腱长度都可认为是MTU与肌肉长度相减所得之差额。对MTU的长度的估值要依据一种间隔——介于具有代表性起源的颅骨表面标志和每块肌肉间彼此嵌入的间隔。视觉识别肌肉（VI）、丘脑腹外侧核肌肉（VL）以及VM肌肉的原点都随股骨粗线延伸，在最近端连线点处齐平于“股骨大转子”——这里我们就把它当做以上三种肌肉的原点。RF MTU则源自脑垂体前部较低级的骼骨。所有肌肉都有MTU的嵌入，这对膝盖骨来说是较高级的保护。这些标识都是利用核磁共振技术来确定的，而且彼此之间都有一定间隙，而这些间隙就是各自MTU的长度。

仁兄，说实话，我这个文章折腾了俩钟头，虽然我是翻译专业的大学生，我也是水平有限，所以希望你能谅解。