What is the primary tensor of the vocal folds?

The primary tensor of the vocal folds is the cricothyroid muscle. This muscle plays a critical role in adjusting the tension of the vocal folds, which is essential for pitch modulation during phonation. When the cricothyroid contracts, it sags the thyroid cartilage forward and down relative to the cricoid cartilage, thereby elongating and tightening the vocal folds. This increased tension raises the pitch of the sound produced.

In contrast, the other muscles mentioned are involved in various functions related to vocal fold movement, but they do not primarily act as tensors. The thyroarytenoid muscle, for example, primarily functions to relax the vocal folds and assists in producing lower pitches. The posterior cricoarytenoid is responsible for abducting the vocal folds (pulling them apart) and is necessary for breathing, while the lateral cricoarytenoid primarily helps with adduction (bringing the vocal folds together) for phonation, but does not mainly contribute to tension adjustments. Thus, the cricothyroid muscle's specific role in tensioning the vocal folds makes it the primary tensor.