Fig. 2
Identification of three planes approximately perpendicular to the curved airflow in the posterior nose in a mid-sagittal section. The white dashed line indicates the selected oblique planes using the anterior edge of the superior ostium of the incisive canal as a pivot point to the (a) anterior edge of the intranasal suture, (b) most ventral part of the frontal bone and (c) posterior edge of the inferior ostium of the incisive canal. The corresponding cross-sectional areas are shown below: (d) CT-CSApost−50, (e) CT-CSApost−80 and (f) CT-CSApost−100. Note the presence of mucosal structures