Movement of the larynx
The thyroid and cricoid can rock back and forth upon each other to change pitch, and the arytenoids can rotate and rock on the cricoid cartilage and can slide a little towards each other. This Netter illustration shows some of the laryngeal muscles and how they move the cartilages and vocal folds (from Netter, F. (2010) Atlas of Human Anatomy 5, Saunder.)
Take a look at this video. You can see the arytenoid cartilages moving the vocal folds together at the midline.