Figure 3 From: Balloon laryngoscopy reduces head extension and blade leverage in patients with potential cervical spine injury Lateral neck radiograph during conventional direct laryngoscopy(informed and written patient consent were obtained). The angle of headextension is defined as 90°–â2.â1, anglebetween AH and horizontal plane; â2, angle betweenocclusal surface of maxillary molarsand horizontal plane;â3, angle of laryngoscope blade levering motion; AH, axis ofhandle; CH, chord corresponding to the radian formed by the proximal third ofthe laryngoscope blade convex surface; E, distal end point of said radian; OS,axis of occlusal surface of maxillary molars or gums.Back to article page