Respiratory activities in relation to external glossal muscles.

In this study, the activities of the two external glossal muscles, Genioglossus (Gg) and Styloglossus (Sg), related to respiration were examined through the electromyography (EMG) in dog. During quiet breathing, no phasic respiratory activity were observed in either muscle. With hypercapnic condition induced by closed rebreathing respiratory system, both Sg and Gg showed phasic respiratory activities in respiration period. At first inspiratory EMG activity was observed from Sg (PaCO2 > 50 mmHg), then after a while from Gg (PaCO2 > 55 mmHg). NaCN injection bilaterally to the carotid body enhances the inspiratory ENG activities in both muscles. Sg was more sensitive than Gg to respiratory stimulation such as hypercapnia or NaCN injection.