|MadSci Network: Anatomy|
With some practice,
you can breathe through your mouth and nose
simultaneously. (At least I can.) In general, your soft palate and uvula
pulled back against the back of your pharynx (upper throat) to isolate the nasal
cavity from the esophagus during eating and mouth breathing, and then opened and
pressed against the back of the tongue to separate the oral cavity from the
pharynx during relaxed, nasal breathing. Most of this occurs unconsciously;
however, most of the muscles that control these processes are also under
voluntary motor control, so that it is quite possible to hold the soft palate
such that it does not contact either surface, leaving both the oral and nasal
cavities open to the pharynx.
Try the links in the MadSci Library for more information on Anatomy.