Fig. 3. Relative positions of the mandible (M; circles ), larynx (L; triangles ), and tongue base (T; squares ) to the nose (N: zero) and the facial line during direct laryngoscopy in patients without difficult laryngoscopy (EL group; left ) and patients with difficult laryngoscopy (DL group; right ). Closed symbols represent positions during sniffing position before direct laryngoscopy. Symbols with double lines represent positions at L3 (time during direct laryngoscopy when Cormack and Lehane grade 3 laryngeal view was first achieved). Open symbols represent positions at Lmax (time during direct laryngoscopy when the maximum arm force was applied to the laryngoscope blade). Background profiles were artificially produced by graphic software (Adobe Photoshop CS2; Adobe Systems Inc., San Jose, CA) so that three anatomical landmarks (M, L, and N) during the sniffing position were on the profiles.