The epiglottis is a structure at the back of the throat formed of cartilage covered with mucous membrane. It is connected by ligaments to other structures of the larynx. When one swallows the epiglottis pivots to cover the opening to the trachea, preventing food or liquids from entering the lungs.

In children, the epiglottis will occasionally become infected with hemophilus influenza, staphylococcus aureus, or streptococcus pneumoniae bacteria. Although easily treated, this condition is a medical emergency because without treatment the epiglottis may swell and block the trachea, causing asphyxia and death. This condition has become rare in countries where vaccination against hemophilus influenza (HIB) is routine.