Which muscle has the greatest control over the fundamental frequency of the laryngeal tone?

• A. Posterior cricoarytenoid
• B. Lateral cricoarytenoid
• C. Cricothyroid
• D. Sternocleidomastoid

Answer: (C)

The key idea is that pitch is set mainly by how tense and long the vocal folds are. When you want a higher pitch, you lengthen and tighten the folds, which makes them stiffer and vibrate faster. The muscle that does this most effectively is the one that tilts the thyroid cartilage forward, lengthening and tightening the vocal folds. That action directly increases the fundamental frequency.

Other muscles either move the folds without increasing tension, or act to open or close the glottis or lift the larynx in a way that doesn’t establish sustained pitch. For example, one muscle opens the vocal folds, which lowers their participation in determining pitch; another helps close the folds but doesn’t significantly raise tension; and an extrinsic neck muscle can elevate the larynx but doesn’t set the steady pitch. So the muscle that lengthens and tightens the folds, raising the tone's basic frequency, is the one that governs fundamental frequency.