Now we’ll look at the muscles that produce movement betwen the cartilages of the larynx. First we’ll see the cricothyroid muscle, then the two crico-arytenoid muscles, then the thyro-arytenoid, transverse arytenoid and ary-epiglottic muscles. Here are the thyroid and cricoid cartilages with all the muscles removed.
We’ll add the crico-thyroid muscle to the picture. Here it is. The cricothyroid muscle arises from here on the cricoid cartilage. It inserts on the thyroid cartilage partly here on the lower border, and partly here, on the inner aspect of the lamina.
The cricothyroid muscle pulls the arch of the cricoid cartilage upwards. In doing so, it pulls the arytenoid cartilages backwards, making the vocal folds longer and tighter.