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

Title

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

Creator

Williams S H; Vinyard C J; Wall C E; Hylander W L

Publisher

Journal of Experimental Zoology Part a-Ecological Genetics and Physiology

Date

2007
2007-04

Description

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.

Subject

electromyography; emg; force; fusion; mandibular symphysis; masseter muscle; movements; pigs; Zoology

Identifier

Format

Journal Article

Search for Full-text

Users with a NEOMED Library login can search for full-text journal articles at the following url: https://libraryguides.neomed.edu/home

Rights

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

Pages

226-240

Issue

4

Volume

307A

Citation

Williams S H; Vinyard C J; Wall C E; Hylander W L, “Masticatory motor patterns in ungulates: A quantitative assessment of jaw-muscle coordination in goats, alpacas and horses,” NEOMED Bibliography Database, accessed April 21, 2021, https://neomed.omeka.net/items/show/7596.

Social Bookmarking