The thyroid cartilage, which forms the Adam's apple, is the largest and uppermost of nine cartilages within the larynx, or voice box. (Cartilage is a strong but flexible tissue.) It houses the vocal folds, also known as the vocal cords.
The thyroid cartilage is composed of two plates, called laminae, that join in the front at an angle of 90 to 120 degrees. The protrusion it creates, visible on the front of the neck, is generally more prominent in men because of a sharper angle in males. The thyroid cartilage typically grows larger during the teenage years, especially in boys, and is seen as a secondary sexual characteristic. Secondary sexual characteristics are indicators of a person’s sex, which develop as they age (usually around puberty). Others include facial hair in men and breasts in women.
Despite its name, the thyroid cartilage has nothing to do with the thyroid gland or its processes. It plays a role in the production of the human voice, providing protection and support for the vocal folds. The muscles of the larynx act on skeletal structures, including the thyroid cartilage, to produce the vibration of the vocal folds, which is necessary to produce vocalization.