Muscle dimensions of the foot in the orangutan and the chimpanzee

Motoharu Oishi, Naomichi Ogihara, Hideki Endo, Yumi Une, Nobutsune Ichihara, Masao Asari, Hajime Amasaki

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


The hindlimbs of two orangutans and four chimpanzees were dissected, and muscle parameters (mass, fascicle length, and physiological cross-sectional area: PCSA) were determined to explore possible interspecies variation in muscle dimensions. Muscle mass and PCSA were divided by the total mass and total PCSA of the entire foot muscles for normalization. The results indicate that the pedal interosseous and the intrinsic pedal digital extensor muscles in the orangutans probably have higher capacity for force production due to their relatively larger PCSAs than in chimpanzees. Moreover, the medial components of the intrinsic muscles exhibited relatively larger mass and PCSA ratios in orangutans. The mass and PCSA ratios of the hallucal muscles were larger in chimpanzees. These differences in foot muscle dimensions of the two species suggest that the orangutan is more specialized for hook-like digital gripping without involvement of the rudimentary hallux, while the chimpanzee is adapted to hallux-assisted power gripping in arboreal locomotion.

Original languageEnglish
Pages (from-to)311-317
Number of pages7
JournalJournal of Anatomy
Issue number4
Publication statusPublished - 2012 Oct
Externally publishedYes


  • Foot
  • Pan
  • Physiological cross-sectional area
  • Pongo

ASJC Scopus subject areas

  • Anatomy
  • Ecology, Evolution, Behavior and Systematics
  • Histology
  • Molecular Biology
  • Developmental Biology
  • Cell Biology


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