Cortical motor representation of the laryngeal muscles inMacaca mulatta

The results of this study are discussed in relation to the possible differential motor innervation by vagal and accessory nerve components of the recurrent laryngeal nerve.

Abstract

In order to determine the cortical areas of representation for the laryngeal muscles inMacaca mulatta, the inferolateral motor portions of both hemispheres were electrically stimulated. Muscular responses were observed under α-chloralose anesthesia. Stimulation of areas on the cortical surface with monopolar eletrodes, by a 100/sec constant current, resulted in differentiated contractions of the thyroarytenoid, cricothyroid or extrinsic laryngeal muscles. Responses were observed visually and measured by force transducers attached to the dissected muscles. InMacaca mulatta, these areas lie primarily within von Bonin and Bailey's histologically designated area FCBm. In several experiments, heart rate was also monitored. At threshold stimulation values, heart rate changes occurred only from the area principally devoted to responses of the cricothyroid muscle. The results of this study are discussed in relation to the possible differential motor innervation by vagal and accessory nerve components of the recurrent laryngeal nerve.