Abstract
It is known that patients with abnormal swallowing, ex, Down's syndrome, extrude the tongue tip to the outside of his or her mouth. Changing the position of the tongue tip however may effect the tongue movements. There are no reports about this influance. This examination was planed to measure the effects of the tongue position on the tongue movements and the activities of the masseter muscle and supra hyoid muscles. The results as are below:
1. As the tip of tongue extrudes, the depth of the bolus formation on the tongue blade may be decreased, and the width may be increased.
2. As the tip of tongue extrudes, the activities of supra hyoid muscles may be increased.
3. There were no tendencies on the activity of masseter muscle due to changes in the position of the tongue.
4. A time lag between the peaks of masseter muscle and supra hyoid muscles were significant due to decreases, from 100 meec to 20 msec.
5. There were no tendencies toward a time lag between the tongue and palatal contact timing and the peak of supra hyoid muscles, but dispersion of time became greater.
We concluded that when tongue extrudes forward, it may be possible to observe abnormal tongue movement and muscle activity for swallowing that cannot be seen normally.
