The influence of jaw-muscle fibre-type phenotypes on estimating maximum muscle and bite forces in primates.

Journal Article (Journal Article)

Numerous anthropological studies have been aimed at estimating jaw-adductor muscle forces, which, in turn, are used to estimate bite force. While primate jaw adductors show considerable intra- and intermuscular heterogeneity in fibre types, studies generally model jaw-muscle forces by treating the jaw adductors as either homogeneously slow or homogeneously fast muscles. Here, we provide a novel extension of such studies by integrating fibre architecture, fibre types and fibre-specific tensions to estimate maximum muscle forces in the masseter and temporalis of five anthropoid primates: Sapajus apella (N = 3), Cercocebus atys (N = 4), Macaca fascicularis (N = 3), Gorilla gorilla (N = 1) and Pan troglodytes (N = 2). We calculated maximum muscle forces by proportionally adjusting muscle physiological cross-sectional areas by their fibre types and associated specific tensions. Our results show that the jaw adductors of our sample ubiquitously express MHC α-cardiac, which has low specific tension, and hybrid fibres. We find that treating the jaw adductors as either homogeneously slow or fast muscles potentially overestimates average maximum muscle forces by as much as approximately 44%. Including fibre types and their specific tensions is thus likely to improve jaw-muscle and bite force estimates in primates.

Full Text

Duke Authors

Cited Authors

  • Holmes, M; Taylor, AB

Published Date

  • October 6, 2021

Published In

Volume / Issue

  • 11 / 5

Start / End Page

  • 20210009 -

PubMed ID

  • 34938437

Pubmed Central ID

  • PMC8361599

International Standard Serial Number (ISSN)

  • 2042-8898

Digital Object Identifier (DOI)

  • 10.1098/rsfs.2021.0009


  • eng

Conference Location

  • England