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Table 2 The landmarks and the reference plane

From: Postoperative changes in the pharyngeal airway space through computed tomography evaluation after mandibular setback surgery in skeletal class III patients: 1-year follow-up

Landmark (abbreviation) Definition
Landmarks
 Na (nasion) “V” notch of frontal and nasal bones
 Ba (basion) Most inferior point of the occipital bone
 Or (orbitale) Most inferior point of the orbital contour
 Po (porion) Most superior point of the external auditory meatus
 Se (sella) Center of sella turcica
 Anterior nasal spine (ANS) Tip of the anterior nasal spine
 B point (B) Deepest point between pogonion and lower incisal alveolus
 CV1 Most anterior inferior point of the anterior arch of the atlas
 CV2 Most anterior inferior point of the body of the 2nd cervical vertebra
 CV4 Most anterior inferior point of the body of the 4th cervical vertebra
Reference plane
 Frankfort horizontal (FH) plane Faces through the right porion and both sides of the orbitalia
 Midsagittal plane A plane perpendicular to the FH plane passing through Na and Ba
 Sella vertical (SV) plane A plane perpendicular to the FH plane passing through Se, Ba, and Na
 CV1 plane A plane parallel to the FH plane passing through CV1
 CV2 plane A plane parallel to the FH plane passing through CV2
 CV4 plane A plane parallel to the FH plane passing through CV4