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Volume changes in human masticatory muscles between jaw closing and opening
T K Goto1, K Tokumori, Y Nakamura
1Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. goto@rad.dent.kyushu-u.ac.jp
Journal of Dental Research
|July 5, 2002
Summary
Jaw muscles, like the masseter and pterygoids, show varied volume changes during jaw opening. The lateral pterygoid muscle significantly decreases in volume, unlike other masticatory muscles.
Area of Science:
- Anatomy
- Biomechanics
- Physiology
Background:
- Jaw muscles exhibit complex, multipennate structures reflecting diverse functional roles.
- Understanding masticatory muscle morphology is crucial for comprehending jaw mechanics.
Purpose of the Study:
- To investigate dynamic volume changes in key jaw muscles during jaw opening and closing.
- To determine if different masticatory muscles exhibit distinct volume alterations.
Main Methods:
- Magnetic resonance imaging (MRI) of the entire head was performed on ten healthy young adults.
- Muscle volumes of the masseter, medial pterygoid, and lateral pterygoid were measured before and after maximum jaw opening.
Main Results:
- The masseter and medial pterygoid muscles showed only minor volume changes.
- The lateral pterygoid muscle demonstrated a significant decrease in volume during jaw opening.
- Normative values for masticatory muscle volume in vivo were established.
Conclusions:
- Masticatory muscles display differential volume changes in response to jaw movement.
- The lateral pterygoid muscle's volume reduction suggests a unique functional adaptation during jaw opening.