Tilt Head, Lift Chin, Check Breathing.

Opening the airway.
Top: Airway obstruction produced by the tongue and the epiglottis.
Bottom: Relief by head-tilt/chin-lift.

Head-tilt/chin-lift maneuver. Perpendicular line reflects proper neck extension, i.e., a line along the edge of the jaw bone should be perpendicular to the surface on which the victim is lying.

Jaw-thrust maneuver.