Figure 1.

Schematic representation of a sagittal cross-section through the upper airway. During inspiration, negative intraluminar pressure pulls three soft tissue elements, the tongue, posterior pharyngeal walls, and soft palate, toward each, thereby reducing the airway lumen in the pharyngeal region. This airway-collapsing action is opposed by pharyngeal dilator muscles, including the genioglossus, geniohyoid, and tensor and levator veli palatini. Additionally, activation of the pharyngeal constrictors stiffens the airway walls. Arrows show approximate directions of the forces exerted during contraction of these major pharyngeal muscles. Image based on a scan of the upper airway in an OSA patient—courtesy of Dr. Richard J. Schwab at the University of Pennsylvania. (Modified from Fig. 1 in Ref. 270 and republished with permission from Informa Healthcare, a member of the Taylor and Francis Group, obtained via the Copyright Clearance Center, Inc.)