Abstract
The purpose of the present study was to investigate the coordination pattern of the laryngeal movements and the orofacial muscle activities when swallowing and to investigate the differences of the swallowing pattern between children and adults, and among different food textures.
The laryngeal movements and orofacial activities from the beginning of chewing to swallowing were recorded using the videofluorography and electromyograms from the temporalis and masseter muscles. In the first study, bread in which barium was added as solid food and Baritogen(Ra)s liquid food were used as the test foods in adults (6 subjects, mean age 29.3 yrs). In the second study, the difference in the swallowing pattern was investigated when ingesting three kinds foods with different texture (boiled fish paste, cooked rice, gummi jelly) in five children (mean age 6.9 yrs) and five adults (mean age 28.7 yrs).
The following results were obtained:
1. The temporalis and masseter muscles were activated before the onset of the sudden laryngeal elevation when swallowing, whereas the onset of the digastric and mylohyoid muscles activities nearly coincided with the laryngeal elevation.
2. Two types of swallowing pattern, the one-step motion and the two-step motion, were observed during swallowing of the solid food. As to the one-step motion, the swallowing started immediately after the bolus was transported into the middle laryngeal. On the other hand, the two-step motion of the swallowing started with some time-lags after the bolus was once transported into the middle laryngeal.
3. As to the influence of both the amounts of food and the texture of food on the swallowing pattern, there were no differences among amounts of food, texture, and between subject groups in the coordination of each muscle and the laryngeal elevation. There was a tendency however that the onset of muscle activity of adults was earlier than that of children.
In conclusion, it was suggested that no differences due to both the amounts of food and food texture were found in the coordination pattern of the laryngeal movements and orofacial muscle activities at swallowing, but there were some differences between children and adults in the swallowing pattern.
