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Motor-unit territory in the human masseter muscle
1Department of Clinical Dental Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, Canada.
Archives of Oral Biology
|January 1, 1991
Summary
This study reveals larger motor-unit territories in the human masseter muscle than previously thought. These findings suggest distinct anatomical compartments within the masseter, enabling selective motor control.
Area of Science:
- Neuromuscular physiology
- Human anatomy
Background:
- Previous studies suggested focal motor-unit territories in the human masseter.
- Limitations in 3D localization and electromyography may have led to underestimation of territory size.
Purpose of the Study:
- To accurately determine the extent of motor-unit territories in the human masseter muscle.
- To investigate the relationship between motor-unit territories and muscle anatomy.
Main Methods:
- Recorded single motor-unit responses from 32 paired-needle sites in human masseter muscles.
- Utilized stereotactic localization, optical systems, and magnetic resonance imaging for 3D site mapping.
- Analyzed territory orientation and size relative to anatomical compartments.
Main Results:
- Motor-unit territories were larger than previously reported.
- Territories exhibited a preferred antero-posterior orientation.
- Territory size correlated with anatomical compartments within the masseter.
Conclusions:
- The human masseter muscle contains larger motor-unit territories than previously understood.
- These territories are organized within distinct anatomical compartments.
- This compartmentalization provides a basis for selective regional motor control of the masseter.