larynx The larynx is the ‘voicebox’, the organ in the neck that plays a crucial role in speech and breathing. The channels for air and for food, which share the pharynx at the back of the nose and mouth, diverge at this point, leading respectively to the trachea and to the oesophagus. The opening for air through the larynx is known as the glottis, and the epiglottis, below and behind the tongue, plays a necessary part in closing off the glottis during swallowing.

The larynx has three important functions: control of the airflow during breathing, protection of the airway below it, and production of sound for speech. The main part of the framework of the larynx is the thyroid cartilage, and it is the front part of this that can easily be seen and felt as the ‘Adam's apple’. The larynx rests on the ring-shaped cricoid cartilage, and below this is the trachea. Above, and attached by ligaments to the larynx at the front, is the U-shaped hyoid bone that provides support and moves upwards with the larynx during swallowing. Halfway down the larynx the paired vocal folds (commonly known as the vocal cords), formed by ligaments covered with mucous membrane, project inwards from its wall. The vocal folds form a ‘V’ shape, open towards the back. At the rear end of each vocal fold are the small arytenoid cartilages. Many small muscles are attached to these, and their action can vary the size of the aperture, by pulling the arytenoids apart or drawing them nearer together, widening or narrowing the ‘V’. This movement occurs rhythmically during inhalation and exhalation in regular quiet breathing. Closure of the glottis occurs only momentarily during swallowing; abnormally, near-closure (laryngospasm) seriously obstructs breathing and causes stridor — high-pitched and noisy breathing.

During speech, singing, or playing a wind instrument, the size of the aperture is narrowed and varied, to produce sounds of different pitch. This increased resistance to airflow out of the lungs converts the flow to a rapid pulsation as it passes between the vocal folds; this produces sound that is then modified by the upper vocal tract.

Marjorie P. Lorch

lar·ynx / ˈlaringks; ˈler-/ • n. (pl. la·ryn·ges / ləˈrinˌjēz/ or lar·ynx·es) Anat. the hollow muscular organ forming an air passage to the lungs and holding the vocal cords in humans and other mammals; the voice box.

larynx The anterior portion of the trachea (windpipe) of tetrapod vertebrates, which in amphibians, reptiles, and mammals contains the vocal cords. Movement of the cartilage in the walls of the larynx (by means of the laryngeal muscles) alters the tension of the vocal cords. This changes the pitch of the sound emitted by the vocal cords when they vibrate. The final voiced sound is modified by resonance within the oral and nasal cavities.

larynx (voice-box) Triangular cavity located between the trachea and the root of the tongue. Inside it are the vocal cords, which are thin bands of elastic tissue. The vocal cords vibrate when outgoing air passes over them, setting up resonant waves that are changed into sound by the action of throat muscles and the shape of the mouth. Inflammation of the larynx and vocal cords is called laryngitis. Symptoms include sore throat, coughing and breathing difficulties. It is usually due to a respiratory tract infection.

LARYNX. An anatomical term for the modified upper part of the trachea (windpipe) of air-breathing animals. It is commonly known as the voice box in humans because of its importance in the creation of the voice. It contains the VOCAL CORDS or folds and influences voice quality. The front cartilage of the larynx is the Adam's apple, prominent in adult males. See SPEECH.