Pulsatile control of the human masticatory muscles

Area of Science:

• Biomechanics
• Neuroscience
• Human Physiology

Background:

• Jaw tremor is a physiological phenomenon that can provide insights into the control of the masticatory system.
• Understanding jaw tremor characteristics and its relationship with muscle activity is crucial for diagnosing and treating related neurological or musculoskeletal disorders.

Purpose of the Study:

• To analyze the spectral characteristics of human jaw acceleration during rest and voluntary movements.
• To compare jaw tremor with finger tremor.
• To investigate the coherence between jaw tremor and the activity of masticatory muscles (masseter and digastric).

Main Methods:

• Spectral analysis of jaw acceleration.
• Measurement of tremor frequency and power during jaw rest and movement.
• Electromyography (EMG) to record masseter and digastric muscle activity.
• Coherence analysis between jaw acceleration and muscle activity.

Main Results:

• Human mandible exhibits a resting tremor peak frequency around 6 Hz, which shifts with jaw movement speed.
• Finger tremor at rest and during slow movements averages 8 Hz, with increased power at higher speeds.
• Jaw tremor showed coherence with masseter and digastric muscle activity, particularly during voluntary movements.
• Antagonistic muscle activity (masseter and digastric) was out of phase, suggesting pulsatile control.

Conclusions:

• The human masticatory system appears to be under pulsatile control, similar to the finger system.
• Jaw tremor characteristics vary with movement speed and are linked to underlying muscle activity patterns.
• The findings support the hypothesis of rhythmic neural control influencing jaw movements.