The mouth is also called the buccal cavity. As food is placed in the mouth it is chewed (masticated). Chewing increases the surface area of the food allowing the enzymes in the mouth to begin hydrolysis. It also mixes the food with saliva, which moistens it for swallowing, and begins to solubilise some of the food.
Salivary amylase is the only enzyme secreted into the mouth. Salivary amylase acts on starch and breaks it down into the disaccharide maltose. Only some starch digestion actually takes place in the mouth.
Once chewed, the food is pressed against the soft palate forming a bolus which is then swallowed. Swallowing forces the bolus into the oesophagus. This is a simple tube with muscular walls that propels the food along by peristalsis.
Peristalsis is the muscular movement, which moves food through the entire digestive tract. It is an involuntary process, and it consists of a wave of contractions of the circular muscles in the wall of the digestive tract, pushing the food through the tract.