Larynx

The larynx contains three unpaired cartilages: the thyroid cartilage forming anterior and lateral walls, the cricoid cartilage forming the inferior wall, and the epiglottis appearing as a leaf-shaped structure posteriorly. Three paired cartilages—arytenoid, corniculate, and cuneiform—form lateral and posterior walls, supporting the vocal folds and epiglottis.

The thyroid cartilage is more prominent in males and visible from the outside as the Adam's apple due to anatomical sex differences in laryngeal development. This cartilage forms the anterior and lateral walls of the larynx, and its increased size in males makes it a distinguishing external feature.

During phonation, air from the lungs passes through the larynx, causing the vocal folds to vibrate and create sound waves. The glottis, consisting of paired mucous membrane folds and the space between them called the rima glottidis, works with intrinsic and extrinsic muscles to move systematically and produce voice.

The larynx connects the laryngopharynx with the trachea, serving as a pathway for air to enter the lungs during respiration. The vocal cords abduct (open wide) during inhalation to maximize airflow, while during exhalation they can remain open for normal breathing or close to allow pressure buildup for coughing or lifting.

The hyoid bone supports the larynx through the thyrohyoid membrane, a ligament that connects the hyoid bone to the thyroid cartilage. This connection helps stabilize the larynx in the neck, working alongside muscles like the sternothyroid and thyrohyoid muscles to move and position the larynx.

The pitch and tone of the voice are altered by changing the tension and length of the vocal cords, controlled by the cricothyroid and thyroarytenoid muscles. Voice volume is determined by the force of airflow from the lungs and the tension applied to the vocal cords during phonation.

The larynx receives nerve supply from branches of the vagus nerve: the recurrent laryngeal nerves and superior laryngeal nerves. These nerves control the intrinsic and extrinsic muscles of the larynx, enabling coordinated movement of cartilages and vocal folds for both respiration and voice production.