The larynx is the body responsible for phonation, or the issuing of sound. It is located in the neck, between the pharynx and the trachea, and it looks like a hollow cylinder. The larynx also allows the passage of the inhaled air (from the nose and mouth to the bronchi) and exhaled air (from the bronchi toward the nose and mouth). It is provided with a closure mechanism, which prevents the chewed food (bolus food) to get stuck into the airways during swallowing.
What is the larynx?
The larynx is the body responsible for speech, or the issue of sound. The shape and texture that characterize it are rigid due to the cartilages (eleven in total, including five major cartilages) that are part of its structure. The various cartilages are articulated with each other through ligaments; the mobility of the various portions of the cartilage and the whole organ is given by the presence of a rich muscular apparatus.
Ideally the larynx is divided into three portions: the upper portion is also called "supraglottic" (at the height of the epiglottis) and its cavity takes the name of the vestibule of the larynx; a central portion that is located at the level of the glottis and, below the central portion, a lower portion composed externally by muscles and internally lined by a mucous membrane. The larynx starts behind the tongue, where it ends the pharynx, and continues in the trachea.
On average the larynx in an adult is long 4 cm, it has 4 cm in width and 3.5 cm in diameter; these dimensions, however, may vary from individual to individual, depending on age and gender. During puberty this organ undergoes major changes: if in childhood, in fact, the larynx is rather small in size, during the years of sexual maturation it grows rapidly, reaching its final dimension. Some of the changes that occur at puberty involve changes in the tone of voice typical of this time of life and especially noticeable in males. This organ is usually shorter in women than in men.
What function does the larynx serve?
The primary function of the larynx is to protect the lower air way by closing quickly upon mechanical stimulation, which stops respiration and prevents foreign matter from entering the airway.
The larynx, in addition to allowing the emission of sounds (phonation), it also allows the passage of the inhaled air (from the nose and mouth to the lungs) and exhaled air (from the lungs to the nose and mouth).
The larynx moves upward and forward to help open the esophagus for the passage of swallowed food. During swallowing, the laryngeal cavities are closed in order to prevent aspiration of swallowed matter into the lungs. However, during respiration the laryngeal cavities are open while some of the laryngeal muscles abduct the vocal folds and thus increase the diameter of the laryngeal airway. Finally, during phonation, the laryngeal cavity called rima glottidis is closed, which causes the vocal cords to vibrate and produce sounds when air is forced through the closed cavity.