The human mouth (or oral cavity) is the first portion of the alimentary canal that receives food and begins digestion by mechanically breaking up the solid food particles into smaller pieces and mixing them with saliva. In humans Mouth cavity The first space of the mouth is the mouth cavity, bounded laterally and in front by the alveolar arches (containing the teeth), and posteriorily by the isthmus of the fauces. The oral cavity is also known as the mouth which it swallows food and drinks and… (More on Mouth)