Laboratory of Anatomy 1, School of Veterinary Medicine, Azabu University, Kanagawa, Japan.
Department of Mechanical Engineering, Faculty of Science and Technology, Keio University, Kanagawa, Japan.
J Anat. 2018 May;232(5):812-823. doi: 10.1111/joa.12780. Epub 2018 Jan 12.
Comparative analysis of the foot muscle architecture among extant great apes is important for understanding the evolution of the human foot and, hence, human habitual bipedal walking. However, to our knowledge, there is no previous report of a quantitative comparison of hominoid intrinsic foot muscle dimensions. In the present study, we quantitatively compared muscle dimensions of the hominoid foot by means of multivariate analysis. The foot muscle mass and physiological cross-sectional area (PCSA) of five chimpanzees, one bonobo, two gorillas, and six orangutans were obtained by our own dissections, and those of humans were taken from published accounts. The muscle mass and PCSA were respectively divided by the total mass and total PCSA of the intrinsic muscles of the entire foot for normalization. Variations in muscle architecture among human and extant great apes were quantified based on principal component analysis. Our results demonstrated that the muscle architecture of the orangutan was the most distinctive, having a larger first dorsal interosseous muscle and smaller abductor hallucis brevis muscle. On the other hand, the gorilla was found to be unique in having a larger abductor digiti minimi muscle. Humans were distinguished from extant great apes by a larger quadratus plantae muscle. The chimpanzee and the bonobo appeared to have very similar muscle architecture, with an intermediate position between the human and the orangutan. These differences (or similarities) in architecture of the intrinsic foot muscles among humans and great apes correspond well to the differences in phylogeny, positional behavior, and locomotion.
对现生大猿类足部肌肉结构进行比较分析，对于理解人类足部的演化，进而理解人类习惯性双足行走具有重要意义。然而，据我们所知，目前还没有关于人科动物固有足部肌肉尺寸的定量比较的报道。在本研究中，我们采用多元分析的方法对人科动物的足部肌肉尺寸进行了定量比较。通过我们自己的解剖，获得了 5 只黑猩猩、1 只倭黑猩猩、2 只大猩猩和 6 只猩猩的足部固有肌肉质量和生理横截面积（PCSA），并从已发表的文献中获取了人类的相应数据。为了归一化，将肌肉质量和 PCSA 分别除以整个足部固有肌肉的总质量和总 PCSA。基于主成分分析，对人类和现生大猿之间的肌肉结构变化进行了量化。我们的研究结果表明，猩猩的肌肉结构最为独特，具有更大的第一背侧骨间肌和更小的短展肌。另一方面，大猩猩具有较大的小趾展肌，这使其具有独特性。人类的足底方肌较大，与现生大猿类有所区别。黑猩猩和倭黑猩猩的肌肉结构似乎非常相似，处于人类和猩猩之间的中间位置。这些差异（或相似性）与人科动物固有足部肌肉的结构与系统发育、姿势行为和运动方式的差异相对应。
