Fig. 7.
Chin lift-head extension with opening the chin-sternum distance (CSD). The maximum head extension measured on cadavers in 1889 by Martin and Hare (M-H angle ~45 degrees) using Reid’s line (R) is functionally equivalent to the angle measured in awake volunteers in 2007 by Paal et al.120 (P = 42 degrees) using a longitudinal line through a face mask cuff (FM). Illustrator: Stefan Matioc.