pISSN 2234-7518
eISSN 2005-372X
eISSN 2005-372X
Definition of the planes and the measurements
| Planes and measurements | Definition |
|---|---|
| Planes | |
| Sella-Nasion plane | A plane passing through point sella and point nasion |
| Nasion-A plane | A plane passing through point nasion and point A |
| Nasion-B plane | A plane passing through point nasion and point B |
| Mandibular plane | A plane passing through point gonion and point menton |
| Horizontal reference plane (RP1) | RP1 was drawn with a 7 degree below the sella-nasion plane at point sella |
| Frankfort horizontal plane (FHP) | A plane passing through orbitale and porion points |
| Nasion perpendicular (N⊥) | A plane passing through nasion point to chin and perpendicular to FHP |
| Measurements | |
| SNA (°) | The angle between sella-nasion and nasion-A point planes |
| SNB (°) | The angle between sella-nasion and nasion-B point planes |
| ANB (°) | The angle between nasion-A point and nasion-B point |
| FMA (°) | The angle between the FHP and mandibular plane |
| RP1-PNS (mm) | The vertical distance from posterior nasal spine point to RP1 |
| S-Go (mm) | The vertical distance between sella and gonion points |
| RP1-A (mm) | The vertical distance from A point to RP1 |
| N⊥A | The linear distance from A point to nasion perpendicular |
| Ad1-PNS (mm) | The linear distance measured between posterior nasal spine and posterior pharyngeal wall along the line of basion point to posterior nasal spine |
| Ad2-PNS (mm) | The linear distance measured between posterior nasal spine to the adenoid tissue along the line from posterior nasal spine to the midpoint of the line intersecting basion to sella turcica |
| Posterior airway space (PAS) (mm) | The anteroposterior depth of the pharynx measured between the posterior pharyngeal wall and the posterior nasal spine on a line parallel to the FHP through the posterior nasal spine |
| Superoposterior airway space (SPAS) (mm) | The linear distance measured between the posterior pharyngeal wall and the dorsum of the soft palate on a line parallel to the FHP through the middle of the line from the posterior nasal spine to the tip of the soft palate |
| Middle airway space (MAS) (mm) | The linear distance measured between the posterior pharyngeal wall and the dorsum of the tongue on a line parallel to the FHP through the tip of the soft palate |
| Inferior airway space (IAS) (mm) | The linear distance measured between the posterior pharyngeal wall and the surface of the tongue on a line parallel to the FHP through the most anteroinferior point on the body of the second cervical vertebra |
| Epiglottic airway space (EAS) (mm) | The linear distance measured between the posterior pharyngeal wall and the surface of the tongue on a line parallel to the FHP through the epiglottis tip |