Callitrichidae are small, arboreal New World primates that utilize a variety of locomotor behaviors including trunk-to-trunk leaping (TTL) and horizontal locomotion which involve differential functional demands. Little is known about the relationship between the preferred locomotor behavior and musculoskeletal architecture of these primates. In this study, we compared the musculoskeletal architecture of selected shoulder muscles in two cadavers each of the trunk-to-trunk leaper Cebuella pygmaea and the mainly pronograde quadrupedally moving Saguinus imperator subgrisescens. Contrast-enhanced microfocus computed tomography (µCT) was used to virtually dissect the cadavers, produce muscle maps, and create 3D reconstructions for an image-based analysis of the muscles. Muscle lengths, muscle volumes, and osteological muscle moment arms were measured, and the anatomical cross-sectional areas (ACSA) were calculated. We expected the muscles of the forelimb of S. imperator to be larger in volume and to be relatively shorter with a larger ACSA due to a higher demand for powerful extension in the forelimbs of this horizontally locomoting species. For C. pygmaea, we expected relatively larger moment arms for the triceps brachii, supraspinatus, infraspinatus and subscapularis, as larger moment arms present an advantage for extensive vertical clinging on the trunk. The muscles of S. imperator were relatively larger in volume than in C. pygmaea and had a relatively larger ACSA. Thus, the shoulder muscles of S. imperator were suited to generate relatively larger forces than those of C. pygmaea. Contrary to our expectations, there were only slight differences between species in regard to muscle lengths and moment arms, which suggests that these properties are not dependent on the preferred locomotor mode. The study of this limited dataset demonstrates that some but not all properties of the musculoskeletal architecture reflect the preferred locomotor behavior in the two species of Callitrichidae examined.

Callitrichidae 是小型树栖新大陆灵长类动物，它们利用各种运动行为，包括躯干到躯干跳跃 (TTL) 和涉及不同功能需求的水平运动。关于这些灵长类动物的首选运动行为与肌肉骨骼结构之间的关系知之甚少。在这项研究中，我们比较了两具尸体中选定肩部肌肉的肌肉骨骼结构，每具尸体的躯干到躯干跳跃者Cebuella pygmaea和主要前行四足移动的Saguinus imperator subgrisescens. 对比增强微焦点计算机断层扫描 (µCT) 用于虚拟解剖尸体，生成肌肉图，并为基于图像的肌肉分析创建 3D 重建。测量肌肉长度、肌肉体积和骨学肌肉力臂，并计算解剖横截面积（ACSA）。我们预计S. imperator前肢的肌肉体积更大，并且由于对这种水平运动物种的前肢强大伸展的更高需求，更大的 ACSA 会相对较短。对于C. pygmaea，我们预计肱三头肌、冈上肌、冈下肌和肩胛下肌的力臂相对较大，因为较大的力臂具有在躯干上广泛垂直紧贴的优势。S. imperator的肌肉体积比C. pygmaea相对大，ACSA 相对较大。因此，S. imperator的肩部肌肉适合产生比C. pygmaea更大的力. 与我们的预期相反，物种之间在肌肉长度和力臂方面只有轻微的差异，这表明这些特性不依赖于首选的运动模式。对这个有限数据集的研究表明，肌肉骨骼结构的一些但不是所有特性反映了所检查的两种 Callitrichidae 的首选运动行为。