From The Art and Popular Culture Encyclopedia
In animal anatomy, the mouth is the first portion of the alimentary canal that receives food.
Some animal phyla, including vertebrates, have a complete digestive system, with a mouth at one end and an anus at the other. Which end forms first in ontogeny is a criterion used to classify animals into protostome and deuterostome. The first space of the mouth is the mouth cavity, bounded laterally and in front by the alveolar arches (containing the teeth), and posteriorly by the isthmus of the fauces.
In human anatomy