Table 2.

Definition of cephalometric landmarks and reference lines.

1.	SNA	Angle between S-N and N-A
2.	SNB	Angle between S-N and N-B
3.	ANB	Angle between N-A and N-B
4.	NSBa (cranial base flexure),	Angle between S-N and a line from S to Ba
5.	BMeH	Angle between B-Me and Me-H
6.	GoMeN	Angle between Go-Me and Me-N
7.	G-VL	Linear distance along a perpendicular plane from G to VL
8.	S-N	Distance between S and N
9.	N-Ba	Distance between N and Ba
10.	ANS-PNS	Distance between ANS and PNS
11.	PNS-AA (bony oropharynx)	Distance between PNS and AA
12.	PNS-Ba (bony nasopharynx)	Distance between PNS and Ba
13.	MP-H	Linear distance along a perpendicular plane from H to MP
14.	H-VL	Linear distance along a perpendicular plane from H to VL
15.	PNS-P	Distance between PNS and P
16.	MPT	Greatest thickness of the soft palate
17.	TGL	Distance between V and TT
18.	TGH	Linear distance along the perpendicular bisector of the V-TT line to the tongue dorsum
19.	SAS( Superior airway space)	Narrowest part of the airway between PNS and P
20.	PAS (Posterior airway space)	Narrowest part of the airway between P and Go
21.	MAS (Minimum airway space)	Airway width along the Go-B plane