The cricoid cartilage and the arytenoid cartilages can be moved by various muscles to change the length of the vocal cords. Higher pitched tones are produced when only the anterior portions of the cords vibrates. Progressively lower tones result when longer sections of the cords vibrate. Males normally have lower voices than females because males usually have longer vocal cord. The sound produced by the vibrating vocal cords is modified by the tongue, lips, and teeth to form words.
Cartilages form the anterior and lateral sides.
Protect the trachea and maintain an open passageway for air. Posterior wall contains no cartilage and consists of a ligamentous membrane and smooth muscle which can alter the diameter of the trachea. Esophagus lies immediately posterior to the cartilage-free posterior wall of the trachea. Trachea is lined with pseudostratified ciliated columnar epithelium that contains numerous goblet cells. Cilia propel mucus and foreign particles toward the larynx where they can enter the esophagus and be swallowed.