Neuroscience Research Australia (NeuRA), Randwick, New South Wales, Australia.
Graduate School of Biomedical Engineering, University of New South Wales, Sydney, New South Wales, Australia.
J Anat. 2024 Aug;245(2):258-270. doi: 10.1111/joa.14050. Epub 2024 May 1.
The human rotator cuff consists of four muscles, each with a complex, multipennate architecture. Despite the functional and clinical importance, the architecture of the human rotator cuff has yet to be clearly described in humans in vivo. The purpose of this study was to investigate the intramuscular, intermuscular, and interindividual variations in architecture and moment arms of the human rotator cuff. Muscle volumes, fascicle lengths, physiological cross-sectional areas (PCSAs), pennation angles, and moment arms of all four rotator cuff muscles were measured from mDixon and diffusion tensor imaging (DTI) scans of the right shoulders of 20 young adults. In accordance with the most detailed dissections available to date, we found substantial intramuscular variation in fascicle length (coefficients of variation (CVs) ranged from 26% to 40%) and pennation angles (CVs ranged from 56% to 62%) in all rotator cuff muscles. We also found substantial intermuscular and interindividual variations in muscle volumes, but relatively consistent mean fascicle lengths, pennation angles, and moment arms (CVs for all ≤17%). Moreover, when expressed as a proportion of total rotator cuff muscle volume, the volumes of individual rotator cuff muscles were highly consistent between individuals and sexes (CVs ≤16%), suggesting that rotator cuff muscle volumes scale uniformly, at least in a younger population without musculoskeletal problems. Together, these data indicate limited interindividual and intermuscular variability in architecture, which may simplify scaling routines for musculoskeletal models. However, the substantial intramuscular variation in architecture questions the validity of previously reported mean architectural parameters to adequately describe rotator cuff function.
人类肩袖由四块肌肉组成，每块肌肉都具有复杂的多羽状结构。尽管肩袖在功能和临床方面具有重要意义，但人类肩袖的结构在体内尚未得到明确描述。本研究旨在研究人类肩袖的肌肉内、肌肉间和个体间的结构和力臂的变化。使用 20 名年轻成年人的右肩 mDixon 和弥散张量成像（DTI）扫描，测量了所有四块肩袖肌肉的肌肉体积、肌束长度、生理横截面积（PCSAs）、羽状角和力臂。根据迄今为止最详细的解剖，我们发现所有肩袖肌肉的肌束长度（变异系数（CVs）范围为 26%至 40%）和羽状角（CVs 范围为 56%至 62%）存在很大的肌肉内差异。我们还发现肌肉体积、肌束长度、羽状角和力臂在肌肉间和个体间存在很大的变化，但平均肌束长度、羽状角和力臂相对一致（所有 CVs≤17%）。此外，当以个体肩袖肌肉体积占总肩袖肌肉体积的比例表示时，个体和性别之间的单个肩袖肌肉体积非常一致（CVs≤16%），这表明肩袖肌肉体积至少在没有肌肉骨骼问题的年轻人群中均匀缩放。总之，这些数据表明结构的个体间和肌肉间变化有限，这可能简化了肌肉骨骼模型的缩放例程。然而，结构上的大量肌肉内差异质疑了先前报道的平均结构参数在充分描述肩袖功能方面的有效性。
