Which intrinsic muscle of the larynx is primarily responsible for the vibration of the vocal folds?

The thyrovocalis muscle is primarily responsible for the vibration of the vocal folds. This muscle is part of the thyroarytenoid muscle group and runs from the thyroid cartilage to the vocal process of the arytenoid cartilage. Its primary action is to tense the vocal folds, which is essential for producing sound. When the thyrovocalis contracts, it alters the tension and length of the vocal folds, leading to changes in pitch during phonation. This controlled tension allows for the precise modulation of sound, enabling the varying frequencies and qualities of human speech.

The other intrinsic muscles play different roles in the overall mechanism of vocal fold function. For instance, the cricothyroid muscle adjusts the length of the vocal folds to change pitch but is not directly responsible for the vibration itself. The thyromuscularis muscle works to relax the vocal folds and can influence their mass but does not initiate vibration. Meanwhile, the lateral cricoarytenoid muscle helps to adduct the vocal folds, bringing them together to initiate sound production, but again does not contribute directly to the vibration that generates sound.