Quantitative Evaluation of the In Vivo Vocal Fold Medial Surface Shape.
Andrew M Vahabzadeh-Hagh, Zhaoyan Zhang, Dinesh K Chhetri
PMID 28089390WHAT IT FOUND
In one dog larynx, activating the thyroarytenoid muscle quickly bulged the vocal fold inward and downward, while the lateral cricoarytenoid adducted it from above and behind.
Together they made a thicker, more rectangular glottis.
Key findings
01Activating the thyroarytenoid muscle bulged the vocal fold inward and downward by 14 milliseconds, nearly closed the middle of the fold by 22 milliseconds, and brought the whole fold together by 47 milliseconds.
02Activating the lateral cricoarytenoid muscle closed the upper back part of the fold, first seen between 16 and 22 milliseconds, and completed by 47 milliseconds with a gap at the middle of the fold.
03Activating both the thyroarytenoid and lateral cricoarytenoid muscles together produced both inward and downward bulging and upper and back closure, making a more rectangular, thicker glottis.
STILL TO COME
How it was doneWhat they found
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What it does not show
The findings come from one mongrel dog, not from people with voice disorders. The larynx was surgically exposed and partly removed, including the false vocal folds, epiglottis, and right side of the larynx, so the setup is not a normal speaking larynx. Only the left vocal fold medial surface was measured. No human speech, voice outcome, therapy, implant, or patient function was tested. The study did not measure vertical differences in vocal fold stiffness during muscle activation. Measurement error was 12 to 20 microns, about one degree in convergence or divergence angle.
Declared interests
No conflicts of interest were declared.
The easy way to misread this
Do not use these shapes as a human treatment target or evidence that a therapy works. The data come from one surgically altered dog larynx, and no therapy, implant, or patient outcome was tested.