Contour analysis of masticatory jaw movements and muscle activity in Macaca mulatta

Kenneth Byrd, C. R. Garthwaite

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Frontal plane mandibular movements during mastication and the associated electromyographic (EMG) activity for left and right superficial masseter, posterior temporalis, anterior temporalis, and anterior belly of the digastric (ABD) were studied for two adult male Macaca mulatta by the new technique of 'contour' analysis. Contour analysis allowed graphic and quantitative portrayal of multiple chew cycle patterns of mandibular movement and EMG activity during active mastication. A series of computer programs (ATS, ATSED, ATSXYZ) facilitated the collection, editing and definition, and finally processing of these masticatory data into contour plots. These preliminary data indicated the essential symmetry of mandibular movement patterns, high chew cycle variability inferior to occlusion, multiple centers of intense EMG activity for balancing-side superficial masseter, and no difference between working-side anterior and posterior temporalis EMG patterns. Maximum EMG amplitude was found in the area of buccal phase power stroke (BPS). Maximum EMG amplitude for ABD was located medial and inferior to occlusion; all other muscle maximum amplitudes were buccal and inferior to occlusion. The location of maximum EMG amplitues for superficial masseter and ABD were closer to occlusion (more superior) during mastication of carrot than were maximum amplitudes during biscuit mastication. The absence of any detectable shift of EMG maximum amplitude location between biscuit and carrot for posterior and anterior temporalis suggested, along with the continuous EMG activity of working-side posterior temporalis, a secondary role for the temporalis (compensation for superficial masseter activity) during active mastication.

Original languageEnglish (US)
Pages (from-to)391-399
Number of pages9
JournalAmerican Journal of Physical Anthropology
Volume54
Issue number3
StatePublished - 1981
Externally publishedYes

Fingerprint

Mastication
mastication
Macaca mulatta
Jaw
jaws
Muscles
muscles
Daucus carota
biscuits
Cheek
carrots
data processing program
stroke
Software
Stroke

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Anthropology

Cite this

Contour analysis of masticatory jaw movements and muscle activity in Macaca mulatta. / Byrd, Kenneth; Garthwaite, C. R.

In: American Journal of Physical Anthropology, Vol. 54, No. 3, 1981, p. 391-399.

Research output: Contribution to journalArticle

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