Anatomy and Physiology of the Larynx and Hypopharynx

The larynx is part of the respiratory system and is located at the upper level of the airway (Fig. 6.1.1). Because of its strategic and unique position, in relation to the crossover between the air and food passages, it is often referred to as part of the upper aerodigestive tract. It is also known as the organ of phonation, owing to special modifications of its anatomy during evolution that have rendered it able to produce voice. Indeed, from a physiologic point of view, it is essentially a valve or sphincter with a triple function: (1) that of an open valve in respiration; (2) that of a partially closed valve whose orifice can be modulated in phonation; (3) that of a closed valve, protecting the trachea and bronchial tree during deglutition.