正常嚥下に関する筋電図的ならびにX線的研究

抄録

Normal deglutition was investigated by the use of a new system of apparatus which enables simultaneous recordings of four-channel electromyography superimposed on fluoroscopic X-ray images. Four normal male adults served as the subjects. The muscles investigated were the genioglossus, geniohyoid, thyrohyoid, thyroarytenoid, thyropharyngeal and cricopharyngeal muscles. The thyropharyngeal muscle was investigated at two different places: upper portion and lower portion.
Movements of the food channel, including elevation of the larynx, supraglottal closure, and opening and closing of the hypopharynx were graphically shown as a function of time. Movements of the tip and the end of bolus were investigated. All these movements were related to the muscular activity.
The results are summarized as follows:
1. Among the muscles investigated, the genioglossus muscle first starts being activated. The geniohyoid muscle follows. Contraction of the thyrohyoid and thyroarytenoid muscles and relaxation of the cricopharyngeal muscle begin nearly at the same time. The relaxation of the cricopharyngeal muscle lasts for approximately 500 msec. The thyropharyngeal muscle presents a series of peristalsislike activation transmitting from above to below during the cricopharyngeal relaxation. The sequence of all the events does not significantly differ according to the body position or to the nature of bolus.
2. The elevation of the larynx begins before the activation of the genioglossus muscle. It reaches to the peak after the thyrohyoid muscle is activated. The peak occurs earlier for deglutition of saliva than for that of barium solution.
3. The supraglottal closing also begins before the contraction of the thyroarytenoid muscle. A complete supraglottal closure takes place around the beginning of the thyroarytenoid contraction and lasts near to the end of the cricopharyngeal relaxation.
4. The pharyngeal cavity at the level of the sixth cervical vertebra starts opening after the cricopharyngeal muscle begin to relax, and it is closed nearly at the same time of the end of the cricopharyngeal relaxation.
5. The tip of the bolus appears near the uvula when the cricopharyngeal muscle is relaxed. The end of the bolus pass the entrance of the esophagus during the cricopharyngeal relaxation.