Epiglottis
The epiglottis is the flap of cartilage lying behind the tongue and in
front of the entrance to the larynx (voice box). At rest, the epiglottis
is upright and allows air to pass through the larynx and into the rest of
the respiratory system. During swallowing, it folds back to cover the
entrance to the larynx, preventing food and drink from entering the
windpipe.
The throat contains both an air passage (the wind pipe) and a food
passage (the esophagus). If these passages were both open when a person
swallowed, air could enter the stomach and food could enter the lungs.
Part of the safety hatch that seals off the windpipe is the "epiglottis,"
a little valvelike cartilage, which works with the larynx to act as a lid
every time we swallow. The larynx draws upward and forward to close the
windpipe. This keeps solid food and liquid out of the respiratory tract.
At the end of each swallow, the epiglottis moves up again, the larynx
returns to rest, and the flow of air into the windpipe continues.
The uvula (Latin for "little grape") is a fleshy piece of muscle, tissue
and mucous membrane that hangs down from the palate. It is the part that
moves upward when we say, "Ah!" It flips up and helps close off the nasal
passages when we swallow.
Contrary to the depictions seen in cartoons, the uvula does not vibrate
during singing and shouting and, in fact, has nothing to do with the
voice.