Figure 4.

Superior and inferior limits of OP and NP volume, PAS, and minAx (area of the most constricted region at the base of the tongue). The circle on the left illustrates the last axial slice before the nasal septum fuses with the posterior wall of the pharynx. In the center image, the top line represents the mentioned axial slice on the sagittal view (superior border of NP). In the lower right image, the area in evidence represents the PAS on the axial view; pp (line passing from palatal plane), 2cv (line passing from the most anteroinferior aspect of the second cervical vertebrae and parallel to pp).