Abstract
Structure of the vocal fold viewed in frontal section was comparatively investigated with larynges of man, dog, cat, rabbit, cow, horse and pig. Observations were made under an operation microscope. The results were as follows:
1. The thyroarytenoid muscle consisted of small muscle bundles. The muscle bundles presented various shapes: triangular, rectangular, or laminar shape.
2. The size of the muscle bundles differed not only between species but also bet-ween different locations. The bundle was big at the lateral and caudal part of the vocal fold, whereas it was small at the medial and cranial part. The former appears to be advantageous for laryngeal closure, and the latter, for phonation. The muscle bundles of the medial part in man were thin and rectangular, indicating a supreme evolution for phonation.
3. The major axis of the cross-section of the muscle bundles was directed horizon-tally, obliquely or vertically. The vertical type, observed in man, appears to be the most adequate to phonation, the horizontal type as observed in cow seems to be the least adequate, and the oblique type as in dog and cat, in between.
4. In man, dog, and cat, the mucosa presented a structure adequate to wavy movement during vibration. The species which did not show such a structure, i. e. cow, horse, pig and rabbit, appears to have poor phonatory function, regardless of the exsistence of separated ventricular and vocal folds.
5. The elastic conus presented a similar tendency as observed in the mucosa.
