This study was designed to clarify the neural interaction between the two physiological mechanisms which induced velar movement. One is the deglutition evoked by repetitive pulse stimulation (RS) of internal branch of the superior laryngeal nerve (In-SLN). Another is the reflex from the levator veli palatini evoked by the afferent nerve stimulation of pharyngeal branches of glossopharyngeal nerve (Ph-GPN). Five adult dogs were used as experimental animals under an intraperitoneum anesthesia by thiopental sodium.
Results were summarized as follows:
1. RS applied to In-SLN, induced deglutition many times in one minute in 10 to 100 msec of stimulus interval (SI). The frequency of deglutition reached maximum at 30 msec of SI.
2. RS was applied to the afferent fibers of Ph-GPN which evoked levator reflexes under a condition of RS of In-SLN to induce deglutition. RS in 10 to 100 msec of SI to the afferent fibers of Ph-GPN decrease the frequency of deglutition.
