Macaque masseter muscle

Internal architecture, fiber length and cross-sectional area

Susan Anton

    Research output: Contribution to journalArticle

    Abstract

    Models of mastication require knowledge of fiber lengths and physiological cross-sectional area (PCS): a proxy for muscle force. Yet only a small number of macaques of various species, ages, and sexes inform the previous standards for masseter muscle architecture. I dissected 36 masseters from 30 adult females of 3 macaque species - Macaca fascicularis, M. mulatta, M. nemestrina - using gross and chemical techniques and calculated PCS. These macaques have mechanically similar dietary niches and exhibit no significant difference in masseter architecture or fiber length. Intramuscular tendons effectively compartmentalize macaque masseters from medial to lateral. Fiber lengths vary by muscle subsection but are relatively conservative among species. Fiber length does not scale with body size (mass) or masseter muscle mass. However, PCS scales isometrically with body size; larger animals have greater force production capabilities. PCS scales positively allometrically with facial size; animals with more prognathic faces and taller mandibular corpora have greater PCS, and hence force, values. This positive allometry counters the less efficient positioning of masseter muscles in longer-faced animals. In each case, differences in PCS among species result from differences in muscle mass not fiber length. Masseter PCS is only weakly correlated with bone proxies previously used to estimate muscle force. Thus predictions of muscle force from bone parameters will entail large margins of errors and should be used with caution.

    Original languageEnglish (US)
    Pages (from-to)441-462
    Number of pages22
    JournalInternational Journal of Primatology
    Volume20
    Issue number3
    StatePublished - 1999

    Fingerprint

    Macaca
    muscle
    muscles
    animal
    bone
    body size
    bones
    Macaca nemestrina
    animals
    fibre
    allometry
    Macaca fascicularis
    mastication
    tendons
    Macaca mulatta
    positioning
    niche
    niches
    prediction
    gender

    Keywords

    • Allometry
    • Macaca
    • Mandible
    • Mastication
    • Muscle architecture

    ASJC Scopus subject areas

    • Animal Science and Zoology

    Cite this

    Macaque masseter muscle : Internal architecture, fiber length and cross-sectional area. / Anton, Susan.

    In: International Journal of Primatology, Vol. 20, No. 3, 1999, p. 441-462.

    Research output: Contribution to journalArticle

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