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Updated: Jul 18, 2026
06:46
In Vivo Functional Assessment of Rat Masseter Muscle Following Surgical Creation of a Volumetric Muscle Loss (VML) Injury
Published on: November 15, 2024
Developmental and functional considerations of masseter muscle partitioning
C G Widmer1, A W English, J Morris-Wiman
1Department of Orthodontics, University of Florida, Gainesville, FL 32610-0444, USA. widmer@dental.ufl.edu
Archives of Oral Biology
|November 18, 2006
Summary
The masseter muscle
Area of Science:
- Anatomy and Physiology
- Biomechanics
- Developmental Biology
Background:
- The masseter muscle is crucial for mastication, swallowing, and speech.
- Its complex structure enables precise mandibular positioning and force generation.
- Internal tendon architecture creates neuromuscular compartments with unique biomechanical properties.
Purpose of the Study:
- To investigate the developmental programming and functional refinement of the masseter muscle.
- To explore the role of sex hormones in masseter muscle fiber-type distribution.
- To understand the nerve dependency in masseter muscle development and maturation.
Main Methods:
- Analysis of masseter muscle's internal organization and compartmentalization.
- Investigation of myosin heavy chain (MyHC) fiber-type distribution and its sexual dimorphism.
- Examination of hormonal influences (testosterone) on muscle fiber phenotype.
- Assessment of nerve dependency in muscle development, myotube generation, and endplate maturation.
Main Results:
- Masseter muscle form is pre-programmed before birth.
- Testosterone influences MyHC fiber-type distribution, leading to a faster fiber-type phenotype in males.
- Early muscle organization and MyHC expression are nerve-independent.
- Secondary myotube generation and endplate maturation are nerve-dependent.
- Masseter muscle development is delayed compared to other facial muscles, potentially due to later chewing functional demands.
Conclusions:
- Masseter muscle's intrinsic form is genetically determined, while its contractile properties adapt postnatally.
- Understanding these developmental processes is key to comprehending masseter muscle function.
- Further research is needed to elucidate motor control mechanisms for discrete masseter muscle elements.
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