A method to predict muscle control in the kinematically and mechanically indeterminate human masticatory system

Area of Science:

• Biomechanics
• Human Physiology
• Robotics

Background:

• The human masticatory system presents unique challenges due to its indeterminate nature, with numerous muscles influencing multiple degrees of freedom.
• Understanding muscle activation patterns is crucial for analyzing jaw movements and function.

Purpose of the Study:

• To develop and validate a mathematical method for generating muscle activation patterns for goal-directed movements in the human masticatory system.
• To explore the boundaries of the mandibular working space and influencing factors.

Main Methods:

• Utilized Linear Programming to determine the contribution of each degree of freedom to mandibular movement.
• Applied the method to a six degrees of freedom dynamical model of the masticatory system based on rigid-body dynamics.
• Movement tasks were defined solely by the goal position of a reference point on the mandible.

Main Results:

• The method successfully generated muscle activation patterns for both feasible and infeasible movement tasks.
• Generated movements were often faster than typically observed human jaw movements.
• For infeasible tasks, the movement terminated at the boundary of the working space.

Conclusions:

• The proposed method offers a robust approach to studying the indeterminate human masticatory system.
• It enables exploration of the mandibular working space and identification of factors defining its limits.
• This technique can aid in understanding jaw biomechanics and potential dysfunctions.