Figure 42-5 A, The normal airway. The tongue and other soft tissues are forward, allowing an unobstructed air passage. B, Obstructed airway. The tongue and epiglottis fall back to the posterior pharyngeal wall, occluding the airway. (Adapted from Dorsch JA, Dorsch SE: Understanding Anesthesia Equipment, 4th ed. Baltimore, Williams & Wilkins, 1999.)