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Masticatory motor patterns in ungulates: a quantitative assessment of jaw-muscle coordination in goats, alpacas and horses.

Publication ,  Journal Article
Williams, SH; Vinyard, CJ; Wall, CE; Hylander, WL
Published in: Journal of experimental zoology. Part A, Ecological genetics and physiology
April 2007

We investigated patterns of jaw-muscle coordination during rhythmic mastication in three species of ungulates displaying the marked transverse jaw movements typical of many large mammalian herbivores. In order to quantify consistent motor patterns during chewing, electromyograms were recorded from the superficial masseter, deep masseter, posterior temporalis and medial pterygoid muscles of goats, alpacas and horses. Timing differences between muscle pairs were evaluated in the context of an evolutionary model of jaw-muscle function. In this model, the closing and food reduction phases of mastication are primarily controlled by two distinct muscle groups, triplet I (balancing-side superficial masseter and medial pterygoid and working-side posterior temporalis) and triplet II (working-side superficial masseter and medial pterygoid and balancing-side posterior temporalis), and the asynchronous activity of the working- and balancing-side deep masseters. The three species differ in the extent to which the jaw muscles are coordinated as triplet I and triplet II. Alpacas, and to a lesser extent, goats, exhibit the triplet pattern whereas horses do not. In contrast, all three species show marked asynchrony of the working-side and balancing-side deep masseters, with jaw closing initiated by the working-side muscle and the balancing-side muscle firing much later during closing. However, goats differ from alpacas and horses in the timing of the balancing-side deep masseter relative to the triplet II muscles. This study highlights interspecific differences in the coordination of jaw muscles to influence transverse jaw movements and the production of bite force in herbivorous ungulates.

Duke Scholars

Published In

Journal of experimental zoology. Part A, Ecological genetics and physiology

DOI

EISSN

1932-5231

ISSN

1932-5223

Publication Date

April 2007

Volume

307

Issue

4

Start / End Page

226 / 240

Related Subject Headings

  • Zoology
  • Motor Activity
  • Masticatory Muscles
  • Mastication
  • Male
  • Jaw
  • Horses
  • Goats
  • Female
  • Electromyography
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Williams, S. H., Vinyard, C. J., Wall, C. E., & Hylander, W. L. (2007). Masticatory motor patterns in ungulates: a quantitative assessment of jaw-muscle coordination in goats, alpacas and horses. Journal of Experimental Zoology. Part A, Ecological Genetics and Physiology, 307(4), 226–240. https://doi.org/10.1002/jez.362
Williams, Susan H., Christopher J. Vinyard, Christine E. Wall, and William L. Hylander. “Masticatory motor patterns in ungulates: a quantitative assessment of jaw-muscle coordination in goats, alpacas and horses.Journal of Experimental Zoology. Part A, Ecological Genetics and Physiology 307, no. 4 (April 2007): 226–40. https://doi.org/10.1002/jez.362.
Williams SH, Vinyard CJ, Wall CE, Hylander WL. Masticatory motor patterns in ungulates: a quantitative assessment of jaw-muscle coordination in goats, alpacas and horses. Journal of experimental zoology Part A, Ecological genetics and physiology. 2007 Apr;307(4):226–40.
Williams, Susan H., et al. “Masticatory motor patterns in ungulates: a quantitative assessment of jaw-muscle coordination in goats, alpacas and horses.Journal of Experimental Zoology. Part A, Ecological Genetics and Physiology, vol. 307, no. 4, Apr. 2007, pp. 226–40. Epmc, doi:10.1002/jez.362.
Williams SH, Vinyard CJ, Wall CE, Hylander WL. Masticatory motor patterns in ungulates: a quantitative assessment of jaw-muscle coordination in goats, alpacas and horses. Journal of experimental zoology Part A, Ecological genetics and physiology. 2007 Apr;307(4):226–240.
Journal cover image

Published In

Journal of experimental zoology. Part A, Ecological genetics and physiology

DOI

EISSN

1932-5231

ISSN

1932-5223

Publication Date

April 2007

Volume

307

Issue

4

Start / End Page

226 / 240

Related Subject Headings

  • Zoology
  • Motor Activity
  • Masticatory Muscles
  • Mastication
  • Male
  • Jaw
  • Horses
  • Goats
  • Female
  • Electromyography