Gill Corey M, Bredella Miriam A, DeSilva Jeremy M
Department of Radiology, Pappas Center for Neuro-Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02214, USA; Pappas Center for Neuro-Oncology, Department of Neurology and Cancer Center, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02214, USA; Department of Anthropology, Boston University, Boston, MA 02214, USA.
Department of Radiology, Pappas Center for Neuro-Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02214, USA.
J Hum Evol. 2015 Nov;88:137-145. doi: 10.1016/j.jhevol.2015.07.003. Epub 2015 Aug 28.
The medial cuneiform, namely the curvature and angulation of its distal facet with metatarsal 1, is crucial as a stabilizer in bipedal locomotion and an axis upon which the great toe medially deviates during arboreal locomotion in extant apes. Previous work has shown that facet curvature and angulation in adult dry-bone specimens can distinguish African apes from Homo, and can even distinguish among species of Gorilla. This study provides the first ontogenetic assessment of medial cuneiform curvature and angulation in juvenile (n = 68) and adult specimens (n = 102) using computed tomography in humans and extant ape specimens, including Pongo. Our data find that modern human juveniles initially have a convex and slightly medially oriented osseous surface of the developing medial cuneiform distal facet that flattens and becomes more distally oriented with age. The same pattern (though of a different magnitude) occurs developmentally in the chimpanzee medial cuneiform, but not in Gorilla or Pongo, whose medial cuneiform facet angulation remains unchanged ontogenetically. These data suggest that the medial cuneiform ossifies in a distinguishable pattern between Pongo, Gorilla, Pan, and Homo, which may in part be due to subtle differences in the loading environment at the hallucal tarsometatarsal joint-a finding that has important implications for interpreting fossil medial cuneiforms.
内侧楔骨，即其远侧关节面与第一跖骨的曲率和角度，作为双足运动中的稳定器以及现存猿类在树栖运动中拇趾向内侧偏斜所围绕的轴，至关重要。先前的研究表明，成年干骨标本中的关节面曲率和角度可以区分非洲猿和人类，甚至可以区分大猩猩的不同物种。本研究首次使用计算机断层扫描技术，对人类和现存猿类标本（包括猩猩）的幼年（n = 68）和成年标本（n = 102）的内侧楔骨曲率和角度进行了个体发育评估。我们的数据发现，现代人类青少年发育中的内侧楔骨远侧关节面最初具有凸面且略向内侧的骨表面，随着年龄增长该表面会变平并变得更向远侧。黑猩猩内侧楔骨在发育过程中也出现相同模式（尽管程度不同），但大猩猩和猩猩则不然，它们的内侧楔骨关节面角度在个体发育过程中保持不变。这些数据表明，猩猩、大猩猩、黑猩猩和人类的内侧楔骨以可区分的模式骨化，这可能部分归因于拇趾跗跖关节负荷环境的细微差异——这一发现对解释化石内侧楔骨具有重要意义。
