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| Variable | Unit | Definition |
|
| Landmarks | | |
| ANS | | Anterior nasal spine, the tip of the median, sharp bony process of the maxilla |
| PM | | Pterygo-maxillare, the point at the junction of the pterygo-maxillary fissure and the posterior nasal spine |
| U | | Uvula, the tip of the uvula |
| UPW | | Upper pharyngeal wall, the point of intersection of the line NL to the posterior pharyngeal wall |
| MPW | | Middle pharyngeal wall, the point of intersection of the perpendicular line from U to the posterior pharyngeal wall |
| LPW | | Lower pharyngeal wall, the point of intersection of the perpendicular line from V to the posterior pharyngeal wall |
| V | | Vallecula, the point of intersection of the epiglottis and the base of the tongue |
| NL | | Nasal line, the line joining ANS and PM |
| S | | Center of the sella turcica |
| N | | Nasion, the deepest point in the concavity of nasofrontal suture |
| A | | A point, the deepest point in the concavity of the anterior maxilla between the anterior nasal spine and the alveolar crest |
| B | | B point, the deepest point in the concavity of the anterior mandible between the alveolar crest and the pogonion |
| Me | | Menton, the most inferior point on the body of the chin |
| Go’ | | Gonion’ point, the point of intersection of the tangents of the inferior and posterior borders of the mandible |
| Measurements | | |
| PM-UPW | mm | Depth of the nasopharyngeal airway space from PM to UPW |
| U-MPW | mm | Depth of the retropalatal oropharyngeal airway space from U to MPW |
| PASmin | mm | Depth of the retroglossal oropharyngel airway space, the shortest distance between the base of the tongue and the posterior pharyngeal wall |
| V-LPW | mm | Depth of the hypopharyngeal airway space from V to LPW |
| PM-U | mm | Length of soft palate, the distance from PM to U |
| SPT | mm | Soft palate thickness, the maximal thickness of the soft palate measured perpendicular to PM-U line |
| NL/PM-U | ° | Inclination of the long axis of the soft palate relative to the nasal line |
| SNA | ° | Angle between the S-N line and the N-A line |
| SNB | ° | Angle between the S-N line and the N-B line |
| ANB | ° | Angle between the N-A line and the N-B line |
| TAFH | mm | Total anterior facial height, the distance from N to Me |
| LAFH | mm | Lower anterior facial height, the distance from the intersection of N-Me line and NL line to Me |
| TPFH | mm | Total posterior facial height, the distance from S to Go’ |
| MP/SN | ° | Angle between the S-N line and Me-Go’ line |
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