Single motor units from the medial pterygoid muscle can be active during isometric horizontal and vertical forces.

Autor: Nozad Mojaver, Yalda, Tawadros, Paul B., Moura Ferreira, Polyana, Whittle, Terry, Murray, Greg M.
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Zdroj: Journal of Oral Rehabilitation; Nov2019, Vol. 46 Issue 11, p998-1008, 11p, 2 Color Photographs, 5 Charts, 2 Graphs
Abstrakt: Objectives: To determine (a) whether the medial pterygoid muscle is active in an isometric vertical force task and in isometric horizontal force tasks in the contralateral, protrusion and ipsilateral directions; (b) whether the same single motor units (SMUs) could be active across different directions of isometric force generation; and (c) whether different regions of the medial pterygoid muscle exhibit different patterns of SMU activation during the generation of any one direction of isometric force. Methods: Intramuscular electromyographic (EMG) recordings were made from the right medial pterygoid muscle in 15 healthy participants during isometric force tasks: vertical and horizontal contralateral, protrusion and ipsilateral. A computed tomography scan divided the EMG recording site into a medial or lateral part in each participant. Single motor units were discriminated in each task. Results: Medial pterygoid SMU activity was recorded in 100% of participants for the vertical biting tasks, 86% of participants for the horizontal contralateral and horizontal protrusion tasks and 57% of the horizontal ipsilateral tasks. Of the 72 SMUs that were discriminated, 36% were active in all tasks; 18% were active only in the vertical tasks and 17% were active in the vertical, horizontal contralateral and horizontal protrusion tasks. The proportion of SMUs that was active in at least 1 horizontal task in the lateral part (33/39) was significantly higher than the proportion (21/33) in the medial part (Chi‐Square, P < 0.05). Conclusion: The data are consistent with a stabilisation role for the medial pterygoid muscle in isometric jaw forces in the vertical and horizontal planes. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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