The tongue often is a source of airway obstruction; it falls back and occludes the _________?

The pharynx or throat is often occluded by the tongue falling back and obstructing air flow.  When air enters the nostrils it passes through the nasopharynx, then the oropharynx, and then the pharynx before it enters the trachea.  Jaw thrust or chin lift will pull the tongue off the back of the pharynx to open the airway allowing air flow to the lungs. The trachea is too distal for the tongue to occlude it.