Vibratory Patterns of Normal and Microscopically Operated Larynges: Observation of Lower Surface of Vocal Fold in Dogs

Abstract

The authors investigated the effect of microsurgical intervention involving the canine larynx on vocal fold vibration. In normal cases both lower lips and free edges vibrated symmetrically. The lower lip coincided with the free edge and collided with that of the other side at the midline. Immediately after the collision, the lower lip rapidly retracted laterally at the beginning of a closed phase. It stayed in the most lateral position for the rest of the closed phase until the free edge started to move away laterally. The lower lip then began to move medially to occlude again with the other side. In cases subjected to microsurgery, a part of the mucosal layer of either the upper or the lower surface of the vocal fold was removed. Several weeks after the procedure, vibration was observed. In either case, vibration of the free edge of the operated vocal fold diminished in amplitude and often became earlier in phase than that of the contralateral fold. Usually the lower lip of the operated vocal fold moved away more slowly. In addition, when the extent of epithelial removal was large, the lower lip itself was not elicited.

Key Words:

• lower surface vibration
• mucosal upheava
• lower lip
• microsurgery of larynx
• ultra-high speed cinematography