Levator Veli Palatini Muscle Activity during Swallowing in Relation to Water Volume in Comparison with Blowing at Maximum lntensity

Abstract

Purpose： Velopharyngeal closure is essential not only for speech but also for swallowing．lt is attained to prevent air emission during speech and bolus from entering the nasal cavity during swallowing．lt has been demonstrated that the levator veli palatini muscle， the primary muscle of velopharyngeal closure for speech，is regulated to maintain tight closure in the velopharynx in accordance with strength of task loaded．However，it has not been examined how levator veli palatini muscle activity could be changed in relation to stimulus during swallowing．The purpose of this study is to exarnine whether levator muscle activity during swallowing can be changed in accordance with volume of swallowed water．

Methods： Three normal adults were used as subjects in this study．Each subject was instructed to perform five-time command swallowing of 3ml，5ml，and 10ml of water and to blow at maximum intensity．Measurement of smoothed EMG activity was made at the peak of the EMG curve for swallowing tasks and at 0.2 sec intervals for blowing tasks．

Results： The amplitude of levator activity for swallowing in each subject was variable in comparison with the activity during blowing．However，for each subject，there were no significant changes in levator muscle activity in relation to swallowed water volume．

Conclusion： Levator veli palatini muscle activity for swallowing might not change with swallowed water having a volume less than 10ml．The relationship between levator activity for swallowing and that for blowing at maximum intensity was variable across subjects．