Table 2

Level	Nasal floor level			Epiglottis level		Hyoid bone level
Variable	Transversal distance	Sagittal distance	Area	Transversal distance	Sagittal distance	Transversal distance	Sagittal distance	Area
Craniovertical angles (°)
FH/VER	0.36^a	0.39^a	0.33^a	-	-	-	-	-
NL/VER	-	-	-	-	-	-	-	-
Craniocervical angles (°)
NL/CVT	-	-	-	-	-	0.31^a	0.42^b	0.45^b
NL/OPT	-	-	-	-	-	-	0.42^b	0.31^a
FH/CVT	-	-	-	0.32^a	0.32^a	0.4^b	0.49^c	0.5^c
FH/OPT	-	-	-	0.3^a	0.3^a	0.32^a	0.5^c	0.46^b
Cervicohorizontal angles (°)
CVT/HOR	-	-	-	-	-	-0.43^b	-0.46^b	-0.57^c
OPT/HOR	-	-	-	-	-	-	-0.53^b,d	-0.51^b,d

^aP < 0.05; ^bP < 0.01; ^cP < 0.001. ^dAge effect (P < 0.05). Multiple linear regression analysis.
FH/VER = the angle between Frankfort horizontal and true vertical line; NL/VER = the angle between nasal line and true vertical line; NL/CVT = the angle between nasal line and cervical vertebra tangent line; NL/OPT = the angle between nasal line and odontoid process tangent line; FH/CVT = the angle between Frankfort horizontal and cervical vertebra tangent line; FH/OPT = the angle between Frankfort horizontal and odontoid process tangent line; CVT/HOR = the angle between cervical vertebra tangent and true horizontal line; OPT/HOR = the angle between odontoid process tangent and true horizontal line; OPT/CVT = the angle between odontoid process tangent and cervical vertebra tangent line.