The Larynx and Voice: Basic Anatomy and Physiology
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.
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 result in interference with any or all of these functions.
The framework of the larynx is comprised 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 action is 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 due to trauma, surgery, or other causes.
If this occurs, paralysis of the vocal folds may occur. 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. By contracting
or relaxing the muscles of the arytenoids, the qualities of this sound
can be altered. As the sound produced by the larynx travels through the
throat and mouth, it is further modified to produce speech
