Two syringeal muscles exert direct motor control on the medial vibratory mass. (A) Ventral and (B) dorsal view of the right primary bronchus. The muscles VS and MDS insert directly on cartilaginous pads embedded in the MVM, hence controlling its tension. (C) Medial view of the MVM of the morphome and (D) of a fresh dissection. Contraction of the VS generates a force (FVS) that bends the MVC, thereby stretching (dotted lines) the ML towards the lateral dorsal cartilage (LDC). Energy stored within the MVC is released after VS contraction. This restores VS length back to resting length, and therefore also reduces the tension in the ML back to baseline. Contraction of the MDS generates a force (FMDS) that also increases tension in MVM, but with a different orientation. (E) The rostral view shows that the projected working lines (arrows) of the VS and MDS are aligned along the dorso-ventral axis. Contraction of these muscles therefore results in no or very little adduction of the ML into the bronchial lumen, and modulates tension only. Abbreviations as listed in Table 1. Colors as in previous figures.