The effect of jaw clenching on the electromyographic activities of 2 neck and 2 trunk muscles.
OBJECTIVE
Symptoms of jaw dysfunction are often associated with neck muscle dysfunction or other musculoskeletal problems. This study attempted to quantify the effect of jaw clenching on the electromyographic (EMG) activity of certain neck, trunk, and jaw muscles.


METHODS
The authors recorded EMG muscle activity in the sternocleidomastoid, trapezius, paravertebral, and rectus abdominis muscles in 10 university students at rest and during strong jaw clenching in supine and sitting positions.


RESULTS
In both positions, jaw clenching resulted in increases in neck muscle activity ranging from 7.6 to 33 times resting muscle activity; for the trunk muscles, the increases ranged from 1.4 to 3.3 times resting activity.


CONCLUSIONS
These results add further information to the concept of the interrelatedness of jaw, neck, and trunk muscle activity.
Ehrlich
R
R
School of Physiology and Pharmacology, University of New South Wales, Australia.
Garlick
D
D
Ninio
M
M
D000328:Adult; D000704:Analysis of Variance; D001732:Bite Force; D003799:Dental Stress Analysis; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008410:Masticatory Muscles / Q000502:physiology; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000502:physiology*; D009334:Neck Muscles / Q000502:physiology; D011187:Posture; D017568:Rectus Abdominis / Q000502:physiology