Cephalometric landmarks and reference planes: N (Nasion), S (sella), Ba (basion), Po (porion), Ar (articulare), Or (orbitale), Pt (pterygoid point), PNS (posterior nasal spine), A (point-A), B (point-B), Me (menton), Gn (gnathion), Go (gonion), and H (hyoid). FH, Frankfort horizontal plane; MP, mandibular plane; FP, facial plane. ① SNA (angle formed between sella, nasion, and point A), ② SNB (angle formed between sella, nasion, and point B), ③ facial axis (angle formed between FP and N-Ba), ④ mandibular plane angle (Angle formed between FH plane and mandibular plane), ⑤ gonion angle (angle formed between mandibular plane and Ar-Go). ⑥ S-N (linear distance between S and N), ⑦ Ar-Go (linear distance between Ar and Go), ⑧ Go-Me (linear distance between Go and Me), ⑨ MP-H (linear distance between the mandibular plane and H). ⑩ SPAS (width of the airway behind the soft palate along the line parallel to the Go-B line), ⑪ IAS (width of the airway along the Go-B line), ⑫ UD (soft palate thickness), and ⑬ UL (soft palate length)