Morimoto Naoki, Suwa Gen, Nishimura Takeshi, Ponce de León Marcia S, Zollikofer Christoph P E, Lovejoy C Owen, Nakatsukasa Masato
Laboratory of Physical Anthropology, Graduate School of Science, Kyoto University, Kyoto, Japan.
J Anat. 2015 Mar;226(3):258-67. doi: 10.1111/joa.12270. Epub 2015 Jan 20.
Proximal femoral morphology and associated musculature are of special relevance to the understanding of hominoid locomotor systems. Knowledge of bone-muscle correspondence in extant hominoids forms an important comparative basis for inferring structure-function relationships in fossil hominids. However, there is still a lack of consensus on the correspondence between muscle attachment sites and surface morphology of the proximal femoral diaphysis in chimpanzees. Two alternative observations have been proposed regarding the attachment site positions of gluteus maximus (GM) and vastus lateralis (VL) relative to two prominent surface features of the proximal femoral diaphysis, the lateral spiral pilaster and the inferolateral fossa. Here, we use a combination of virtual and physical dissection in an attempt to identify the exact correspondence between muscle attachment sites and osteological features in two specimens of Pan troglodytes verus. The results show that the insertion of the GM tendon is consistently inferolateral to the lateral spiral pilaster, and that a part of the inferolateral fossa consistently forms the attachment site of the VL muscular fibers. While overall musculoskeletal features are similar in the two specimens examined in this study, GM and VL exhibit different degrees of segregation at the level of the inferolateral fossa. One specimen exhibited tendinous GM fibers penetrating the posteromedial part of VL, with both GM and VL inserting at the inferolateral fossa. In the other specimen, GM and VL were separated by a lateral intermuscular septum, which inserted into the inferolateral fossa. Variation of proximal femoral muscle attachments in chimpanzees is thus greater than previously thought. Our results indicate that a conspicuous osteological feature such as the inferolateral fossa does not necessarily correspond to the attachment site of a single muscle, but could serve as a boundary region between two muscles. Caution is thus warranted when interpreting the surface topography of muscle attachment sites and inferring locomotor functions.
股骨近端形态及相关肌肉组织对于理解类人猿运动系统具有特殊意义。了解现存类人猿骨骼与肌肉的对应关系，为推断化石原始人类的结构 - 功能关系提供了重要的比较基础。然而，关于黑猩猩股骨近端骨干肌肉附着点与表面形态之间的对应关系，目前仍缺乏共识。针对臀大肌（GM）和股外侧肌（VL）相对于股骨近端骨干两个突出表面特征——外侧螺旋嵴和下外侧窝的附着点位置，提出了两种不同的观点。在此，我们结合虚拟解剖和实体解剖，试图确定两只倭黑猩猩标本中肌肉附着点与骨学特征的确切对应关系。结果表明，GM肌腱的止点始终位于外侧螺旋嵴的下外侧，并且下外侧窝的一部分始终构成VL肌纤维的附着点。虽然本研究中检查的两个标本的整体肌肉骨骼特征相似，但GM和VL在下外侧窝水平表现出不同程度的分离。一个标本中，GM肌腱纤维穿透VL的后内侧部分，GM和VL均止于下外侧窝。在另一个标本中，GM和VL被一条外侧肌间隔分开，该肌间隔止于下外侧窝。因此，黑猩猩股骨近端肌肉附着的变异比之前认为的更大。我们的结果表明，像下外侧窝这样明显的骨学特征不一定对应于单一肌肉的附着点，而可能作为两块肌肉之间的边界区域。因此，在解释肌肉附着点的表面地形和推断运动功能时应谨慎。
