Role of the pharyngeal plexus in initiation of swallowing.

SINCLAIR, k%J.JAM J. Role of the pharyngeal pbxus in initiation of swallowing. Am. J. Physiol. 221(5) : 1260-1263. 1971.-In preparation for stimulation studies, 22 cats were electrolytically decerebrated. The intact cephalic branch of the pharyngeal branch of the vagus nerve (Za) was electrically stimulated to determine its role in the initiation of the swallowing reflex. Comparative data were recorded for the superior laryngeal nerve (SLN) and the glossopharyngeal nerve (GPN). Swallowing was noted visually and recorded electromyographically. Stimulation of branch 22a resulted in swallowing in six cases out of 18. Chronaxie and optimum frequency of stimulation for swallowing for branch ,?;?a were 0.11 msec and 30-50 cycles/set, respectively. Afferents for swallowing were shown to be distributed among pharyngeal branches of the GPN. Stimulation studies indicated that the GPN is the primary afferent for swallowing initiated from the pharynx: branch 22a played a minor role. A composite schema is presented of those nerves that were found to contain afferents for swallowing. Small and larger sized fibers are suggested as interacting centrally to explain the observation that electrical stimulation of the SLN elicits swallowing more readily than stimulation of the GPN.