Main movement of thyroid cartilage is forward and down rotation relative to the fixed cricoid cartilage. It is anchored to the trachea inferiorly and thyroid cartilage laterally. Paired arytenoid cartilages articulate with superior part of lamina of cricoid cartilage and are pyramidal in shape. Forms the cricoarytenoid joints. Each cartilage has an apex superiorly, a vocal process anteriorly, and a muscular process laterally from the base.
Epiglottic cartilage gives support and flexibility to the epiglottis.
The shape of the rima glottidis varies according to the position of the true vocal folds. Variations in the length and tension of the true VF and width of the the rima and intensity of expiration change pitch in voice. Posteriorly, where the cartilage is deficient, the trachea is flattened and its wall completed by fibrous tissue and a sheet of smooth muscle. ANS regulation of smooth muscle in walls of bronchioles. Sympathetic nervous system is a bronchodilator.