Fig. 4.

Glottal shape for the interaction between maximal CT activation and graded TA activation. Design layout is same as Fig.1 except now CT is held at maximum stimulation for all rows (grade 6), while TA is added in a graded fashion from grade 0 (‘TA 0’, row 1) to grade 5 (‘TA 5’, row 6). CT activation alone (row 1) results in 25% abduction, 8% lengthening, and 15% narrowing of the mid cord vertical height. TA activation provides dramatic 95-98% adduction beginning at grade 1. CT combined with TA grades 1-3 yields preferential adduction of the inferomedial vocal fold resulting in a divergent glottal configuration. Greater TA activation yields more uniform adduction of the full vertical thickness of the vocal fold. (CT = cricothyroid, inf – sup = inferior to superior, ms = millisecond, post – ant = posterior to anterior, TA = thyroarytenoid).