Doctor Stewart, Otorhinolaryngologist-in-chief at New York Presbyterian Hospital, explains exactly what the tongue is and what it's functions are, including speech, swallowing, and breathing.

Doctor Stewart: Well the tongue really goes all the down into your upper throat, the base of the tongue does. The part you can see in the mouth is actually a small portion of the tongue. The tongue is a combination of several different, you know, sort of folds and arches of tissue that form the tongue. It's basically solid muscle. It's actually very sophisticated, it has all kinds of different functions and moves in all kinds of different directions. It's a very, very strong muscle. So, you know, for speech the tongue is absolutely critical in terms of where it contacts. It has to be able to move in all kinds of different directions. The front needs to contact the teeth and the pallet, farther back, the tongue height, it controls the way you form different vowels and the rest of the whole vocal tract, it gains a lot of coordination and a lot of specialization as you learn speech and articulation and things like that. Probably even more important during swallowing because the tongue forms the food into what's called a bolus, it puts it together into something that's compact and the tongue propels the food back and then actually initiates the first part of the swallowing. And then for breathing, you know, the voice box, the larynx is suspended from the tongue partially. Well the tongue really goes all the way down into your upper throat, the base of the tongue does. The part you can see in the mouth is actually a small portion of the tongue, relatively speaking.