The structure of the crocothyroid joint allows two movements to occur when the cricothyroid muscles contract. 1.The thyroid slides forward over the cricoid and 2. the joint pivots to allow the thyroid cartilage and thyroid closer together. These movements lengthen and tense the vocal folds while thinning the medial edge so that the portion of the vocal folds that vibrates has less mass. These actions serve to raise the frequency of vocal fold vibration.
