Fig. 3. Axial image of computed tomography scan at the level of the mandible (taken from a person unrelated to this study) and the schematic presentations of the axial structural arrangements while the patient is in the supine and lateral positions. BE = bony enclosure; PA = pharyngeal airway; A = mass of soft tissues locating anteriorly; L = mass of soft tissues locating laterally; P = mass of soft tissues locating posteriorly. Note that the amount of soft tissues acting on the mucosa of the pharyngeal airway shown by the shaded area is significantly less while patients are in the lateral than the supine position.