A basic understanding of the anatomy of the larynx and the mechanics of voice production is necessary before a laryngeal disorder can be defined. This page provides a brief overview of these topics. A second page describes the procedures that may be used to visualize laryngeal structure and function.
The larynx is positioned in the anterior neck, slightly below the point where the pharynx divides and gives rise to the separate respiratory and digestive tracts. Because of its location, the larynx plays a critical role in normal breathing, swallowing, and speaking. Damage to the larynx or its tissues can interfere with any or all of these functions.
The framework of the larynx consists mainly of two cartilages, the upper thyroid cartilage (whose anterior prominence is oftentimes felt as the "Adam's apple") and the lower and smaller cricoid cartilage. The epiglottis lies superiorly. This structure protects the larynx during swallowing and prevents aspiration of food.
The vocal folds lie in the center of this framework in an anterior-posterior orientation. When viewed from above, the right and left folds appear as a "V"-shaped structure with the aperture between the "V" forming the entrance to the trachea. At the rear of the larynx on each side, each vocal fold is attached to a small arytenoid cartilage. Many small muscles also attach to the arytenoids. These muscles contract or relax during the various stages of breathing, swallowing and speaking, and their actions are vital to the normal function of the larynx.
Control over these muscles is provided by two branches of the vagus nerve: the recurrent laryngeal nerve and the superior laryngeal nerve. These branches are vulnerable to injury caused by trauma, surgery or other reasons. If this occurs, the vocal folds may experience paralysis. This leads to the hoarseness, aspiration and other symptoms associated with laryngeal nerve injury.
Phonation is a complicated process in which sound is produced for speech. During phonation, the vocal folds are brought together near the center of the larynx by muscles attached to the arytenoids. As air is forced through the vocal folds, they vibrate and produce sound. Contraction or relaxation of the muscles of the arytenoids can alter the qualities of this sound. As the sound produced by the larynx travels through the throat and mouth, it is further modified to produce speech.