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 |

Korean J Orthod 2023;53:35~44 https://doi.org/10.4041/kjod22.117

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