Fig. 1. Airway measures. (A ) 1 marks the horizontal distance lower alveolar process to posterior pharyngeal wall, 2 marks the horizontal distance outermost portion of lower lip to posterior pharyngeal wall, 3 marks the horizontal distance tip of the epiglottis to posterior pharyngeal wall, 4 marks the horizontal distance vallecula to posterior pharyngeal wall. (B ) 5 marks the largest horizontal diameter of the tongue, 6 marks the horizontal distance edge of the tongue to posterior pharyngeal wall at level of the largest horizontal diameter of the tongue, 7 marks the curved length of the soft palate, 8 marks the distance vallecula to tip of the epiglottis, 9 marks the distance posterior base of the epiglottis to tip of the epiglottis. (C ) 10 marks the horizontal distance center of the soft palate to posterior pharyngeal wall, 11 marks the height of the soft palate, 12 marks the vertical distance base of the soft palate to tip of the epiglottis, 13 marks the vertical distance base of the soft palate to vallecula. (D ) 14 marks the volume of the oral airspace, 15 marks the cross-sectional area of the tongue, 16 marks the cross-sectional area of the soft palate and uvula, 17 marks the volume of the retropalatal airspace, 18 marks the volume of the pharyngeal airspace.