The normal swallowing mechanism is usually broken down into 4 phases. The barium swallow X-ray (Videofluoroscopy) can show all 4 phases of a swallow. The contrast material (barium) can be visualized as it flows into the stomach.
The first phase is the preparatory phase. Food is put into the mouth, chewed and moistened with saliva. Muscles and nerves are needed to keep the food in the mouth and prepare it for swallowing.
The second phase is the oral phase. The food is moved from the mouth to the pharynx or back of the throat. The soft palate elevates to keep the food out of the nose and the back of the tongue pushes the food back into the throat. The tongue and palate are very important to this phase.
The third phase is the pharyngeal phase. The food moves into the esophagus from the pharynx. Breathing stops during this part of swallowing in order to prevent food from entering the airway(aspiration).
The fourth phase is the movement of food through the esophagus and gastroesophageal junction to the stomach.