Table 1 Definition of all CT Measurements

D1

Distance between the upper central alveolar ridge and root of the epiglottis

D2

Distance between the root of the epiglottis and glottis midpoint

D3

Distance between the end of the mandible and glottis midpoint

D4

Height of the mandible

D5

Distance between the uvula and posterior pharyngeal wall

D6

Distance between the root of the tongue and posterior pharyngeal wall

D7

Distance between the epiglottis and posterior pharyngeal wall

D8

Length of the epiglottis

D9

Length of the mandibular ramus

D10

Length of the mandible body

D11

Length of the mandible

A1

Angle between lines D1 and D2

A2

The angle between line D2 and the lower edge of the upper central alveolar ridge to the glottis midpoint

A3

The angle of lines D3 and D4

A4

The angle of the point of the lower edge of the upper central alveolar ridge to the trailing edge of the hard palate and then to the root of epiglottis

A5

The angle of the mandible

A6

The angle of the gonion to the angle of the mandible

Airway section area at the tip of epiglottis

The airway section area at the tip of epiglottis

Oral volume

Mouth volume from upper and lower alveolar ridge to the posterior edge of the hard palate

Palatine pharyngeal volume

Palatine pharyngeal volume from the posterior border of the hard palate to the edge of the soft palate

Glossopharyngeal volume

Glossopharyngeal volume from soft palate palatal cusp to epiglottis upper edge.