Swallowing, or deglutition, is an important step in getting the
bolus to our stomach. When we are ready to swallow the bolus, we
place the bolus on the surface of our tongue. The front part of
the tongue touches the area in our mouth just behind the upper
front teeth. Then more parts of the tongue touch the roof of the
mouth, starting with the area closest to the front teeth and
ending with the area closest to the pharynx. This causes the
food to move from the front of the mouth to the back of the
mouth. Depending on whether we have more food that needs to be
chewed in our mouth, we may alternate between chewing the food
and swallowing it. As the food goes into the back of the mouth,
the soft portion of the roof of the mouth lifts up and seals the
sides and the back of the pharynx so that the bolus does not go
into the nose. The base of the tongue (ie, where it attaches to
the floor of the mouth) pulls back and pushes the food against
the walls of the pharynx. The muscles of the pharynx contract in
a wavelike