A model for mylohyoid muscle mechanics

Area of Science:

• Biomechanics
• Musculoskeletal system modeling
• Human jaw mechanics

Background:

• The mylohyoid muscle plays a crucial role in jaw movement.
• Understanding its mechanics is essential for fields like dentistry and prosthodontics.
• Previous models have not fully captured the complex fiber dynamics during jaw opening.

Purpose of the Study:

• To create a mathematical model of the mylohyoid muscle.
• To analyze the muscle's mechanics and force generation during jaw movement.
• To investigate the impact of fiber bending and geometrical changes on muscle function.

Main Methods:

• Developed a model based on muscle morphology and physiological properties.
• Incorporated fiber bending using pulleys simulating digastric muscle interaction.
• Related muscle portion dynamics (force-length, force-velocity) to sarcomere length changes.
• Calculated the effective force component in the sagittal plane as a function of jaw angle.

Main Results:

• Muscle configuration changes significantly and non-uniformly during jaw opening.
• Sarcomere length changes were minimal across muscle portions.
• Muscle portions operated near their optimal force-length relationship.
• Effective muscle force increased with jaw opening angle, varying between anterior and posterior portions.
• Fiber bending was found to substantially increase the sagittal plane force component.

Conclusions:

• The developed model accurately simulates mylohyoid muscle mechanics during jaw opening.
• Mylohyoid muscle portions maintain near-optimal lengths, suggesting efficient function.
• Fiber bending is a significant factor influencing the muscle's contribution to sagittal jaw movements.
• This model provides valuable insights for understanding jaw function and dysfunction.