Neuroscience Research Australia (NeuRA), Sydney, NSW, Australia; School of Biomedical Sciences, University of New South Wales, Sydney, NSW, Australia.
Cerebral Palsy Alliance Research Institute, Discipline of Child and Adolescent Health, The University of Sydney, Sydney, NSW, Australia.
J Biomech. 2023 Jun;155:111661. doi: 10.1016/j.jbiomech.2023.111661. Epub 2023 May 26.
Little is known about the skeletal muscle architecture of living humans at birth. In this study, we used magnetic resonance imaging (MRI) to measure the volumes of ten muscle groups in the lower legs of eight human infants aged less than three months. We then combined MRI and diffusion tensor imaging (DTI) to provide detailed, high-resolution reconstructions and measurements of moment arms, fascicle lengths, physiological cross-sectional areas (PCSAs), pennation angles and diffusion parameters of the medial (MG) and lateral gastrocnemius (LG) muscles. On average, the total lower leg muscle volume was 29.2 cm. The largest muscle was the soleus muscle with a mean volume of 6.5 cm. Compared to the LG muscles, the MG muscles had, on average, greater volumes (by ∼35%) and greater PCSAs (by ∼63%) but similar ankle-to-knee moment arm ratios (∼0.1 difference), fascicle lengths (∼5.7 mm difference) and pennation angles (∼2.7° difference). The MG data were compared with data previously collected from adults. The MG muscles of adults had, on average, a 63-fold greater volume, a 36-fold greater PCSA, and 1.7-fold greater fascicle length. This study demonstrates the feasibility of using MRI and DTI to reconstruct the three-dimensional architecture of skeletal muscles in living human infants. It is shown that, between infancy and adulthood, MG muscle fascicles grow primarily in cross-section rather than in length.
关于人类出生时的骨骼肌结构，目前知之甚少。本研究使用磁共振成像（MRI）测量了 8 名年龄不足 3 个月的人类婴儿小腿 10 块肌肉群的体积。然后，我们结合 MRI 和弥散张量成像（DTI），对内侧（MG）和外侧比目鱼肌（LG）的力臂、肌束长度、生理横截面积（PCSA）、羽状角和弥散参数进行了详细的高分辨率重建和测量。平均而言，小腿总肌肉量为 29.2cm。最大的肌肉是比目鱼肌，平均体积为 6.5cm。与 LG 肌肉相比，MG 肌肉的体积更大（约 35%），PCSA 更大（约 63%），但踝膝力矩臂比（约 0.1 的差异）、肌束长度（约 5.7mm 的差异）和羽状角（约 2.7°的差异）相似。将 MG 数据与之前从成年人收集的数据进行了比较。成年人的 MG 肌肉平均体积大 63 倍，PCSA 大 36 倍，肌束长度长 1.7 倍。本研究证明了使用 MRI 和 DTI 重建活体人类婴儿骨骼肌三维结构的可行性。结果表明，从婴儿期到成年期，MG 肌束主要在横截面上生长，而不是在长度上生长。
