The Relation Between Interangle Span and In Vivo Resultant Force in the Perioral Musculature The variable nature of the perioral system as a force generator is due, in large part, to differences in the spatial arrangement and degree of muscle representation in this region. This fact requires careful consideration when attempting to compare select properties of force dynamics among individual subjects in health and ... Research Article
Research Article  |   April 01, 1991
The Relation Between Interangle Span and In Vivo Resultant Force in the Perioral Musculature
 
Author Affiliations & Notes
  • Steven M. Barlow
    Speech-Orofaclal Physiology Laboratory Program in Neural Science Indiana University
  • Eric M. Muller
    Speech Physiology and Biomechanics Laboratory San Diego State University
  • Requests for reprints should be sent to Steven M. Barlow, Speech-Orofacial Physiology Laboratory, Department of Speech and Hearing Sciences, 3rd and Jordon, Indiana University, Bloomington, IN 47405.
Article Information
Speech / Research Articles
Research Article   |   April 01, 1991
The Relation Between Interangle Span and In Vivo Resultant Force in the Perioral Musculature
Journal of Speech, Language, and Hearing Research, April 1991, Vol. 34, 252-259. doi:10.1044/jshr.3402.252
History: Received December 15, 1989 , Accepted July 13, 1990
 
Journal of Speech, Language, and Hearing Research, April 1991, Vol. 34, 252-259. doi:10.1044/jshr.3402.252
History: Received December 15, 1989; Accepted July 13, 1990

The variable nature of the perioral system as a force generator is due, in large part, to differences in the spatial arrangement and degree of muscle representation in this region. This fact requires careful consideration when attempting to compare select properties of force dynamics among individual subjects in health and disease. The objective of the present study was to determine the relation between an indirect measure of muscle length (interangle span) and in vivo resultant force in the perioral region of normal adult subjects. Perioral force associated with the maximum voluntary contraction (MVC) was found to increase systematically with increases in the span between the load sensitive cantilevers positioned between the corners of the mouth. The active force component of the MVC was significantly greater for male than female subjects, whereas passive forces were equal. Active force is discussed in relation to rest positions of the oral opening and the assessment of the force operating range for speech and other oromotor behaviors in health and disease.

Acknowledgments
Research reported here was supported in part by grants from the National Institutes of Health (NS-19624-05 and DC00365-03), Boys Town National Institute, and the Moody Foundation of Galveston, Texas (grant 88–46 to S.M. Barlow). Special gratitude is given to Dr. Erick Rath, Ms. Jill Phebus, Ms. Dawn Biever, and Ms. Mary Burton for technical support. The authors are appreciative of the thoughtful comments provided by the anonymous reviewers.
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