Fig. 1
Identification of three planes approximately perpendicular to the curved airflow in the anterior nose in a mid-sagittal section. The white dashed line indicates the selected oblique planes using the anterior nasal spine as a pivot point to the (a) posterior edge of the inferior ostium of the incisive canal, (b) anterior edge of the intranasal suture and (c) most ventral part of the frontal bone. The corresponding cross-sectional areas are shown below: (d) CT-CSAant−30, (e) CT-CSAant−60, and (f) CT-CSAant−90. Note the absence of mucosal structures