Unit of Human Anatomy and Embryology, University of Barcelona, C/Casanova 143, 08036 Barcelona, Spain.
Animal Postcranial Evolution (APE) Lab, Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, CT2 7NR, UK.
Ann Anat. 2020 Jul;230:151505. doi: 10.1016/j.aanat.2020.151505. Epub 2020 Mar 12.
To identify anatomical differences in the deltoid tuberosity of Homo sapiens and Pan troglodytes, potentially relating to the different uses of the forelimb in these two phylogenetically related species.
We have used three-dimensional geometric morphometrics (3D GM) to analyze the deltoid tuberosity of scanned humeri from 30 H. sapiens and 27 P. troglodytes. We also used the 3D scans of the humeri to calculate the surface area of the deltoid tuberosity. Finally, we dissected the deltoid muscles of three H. sapiens and three P. troglodytes to determine the relative mass and the physiological cross-sectional area (PCSA) of each part of the muscle.
The 3D GM analysis of the deltoid tuberosity identified an anteroposterior enlargement of the P. troglodytes tuberosity, with a lateral displacement of the middle segment, whereas in H. sapiens, there was a distal displacement of the middle segment. Muscle architecture analysis indicated higher normalized values of the PCSA of the clavicular and acromial deltoid in P. troglodytes.
The anatomical features observed in our P. troglodytes specimens serve to strengthen the three parts of the deltoid muscle. This fact can be related to the use of the forelimb in locomotion, both arboreal and knuckle-walking, in this species. Humans use the forelimb mainly in manipulative tasks, so they do not develop - as do chimpanzees - the anatomical features that increase the deltoid force. Our findings have shown that the different uses of the forelimb in modern humans and common chimpanzees can affect both muscle architecture and bone morphology, either jointly or separately.
鉴定智人和黑猩猩的三角肌粗隆的解剖学差异，这些差异可能与这两种在进化上相关的物种对前肢的不同使用方式有关。
我们使用三维几何形态测量学（3D GM）分析了来自 30 只智人和 27 只黑猩猩的扫描肱骨的三角肌粗隆。我们还使用肱骨的 3D 扫描来计算三角肌粗隆的表面积。最后，我们解剖了 3 只智人和 3 只黑猩猩的三角肌，以确定肌肉各部分的相对质量和生理横截面积（PCSA）。
三角肌粗隆的 3D GM 分析确定了黑猩猩粗隆的前后向增大，中段发生侧向移位，而在智人中，中段发生远端移位。肌肉结构分析表明，黑猩猩锁骨部和肩峰部三角肌的 PCSA 归一化值较高。
我们在黑猩猩标本中观察到的解剖特征有助于加强三角肌的三个部分。这一事实可以与该物种在运动中的前肢使用有关，包括树栖和指节行走。人类主要在前肢的操纵任务中使用，因此不会像黑猩猩那样发展出增加三角肌力量的解剖特征。我们的研究结果表明，现代人类和普通黑猩猩对前肢的不同使用方式可能会同时或分别影响肌肉结构和骨骼形态。
