Fig. 4. Sequence of ventral outside views of the brown thrasher syrinx during the transition from quiet respiration (a), via reconfiguration in preparation for phonation (b), to phonation (c) and return to the starting point (d) induced by electrical brain stimulation. The sequence illustrates the striking rostrad movement during sound production. To illustrate the movement, red arrowheads mark the caudal end of the syringeal midline and blue arrowheads outline the third bronchial cartilage. The movement results in significant stretching of connective tissue in the bronchial section, including the medial tympaniform membranes (the white dotted line outlines the medial edges of the median tympaniform membrane). B, bronchial cartilage; vS, m. syringealis ventralis; vTB, m. tracheobronchialis ventralis.