Fig. 3. Electrical stimulation of m. syringealis ventralis (vS), the largest syringeal muscle in songbirds, does not noticeably change the aperture of the bronchus from the respiratory (a) to the stimulated (b) position. However, upon stimulation, a twitching motion of the medial labium is apparent in the video, suggesting that stretching of the medial labium along the rostro-caudal axis may occur (yellow arrowheads). Angioscope position approximately as illustrated in Fig. 1B. D, dorsal side; V, ventral side; BL, bronchial lumen; LL, lateral labium; ML, median labium; SM, semilunar membrane.
