We take eating and drinking for granted untill we cannot eat or drink. Disturbance in these vital functions causes misery, disease and death.
Normal swallowing in essence consists of two phases;
One may conceptulaise two functional units for swallowing, each consists of the three basic components of pump, sphincter and resevoir; the first functional unit is responsible for the movement of the bolus of fluid and or food from the mouth into the esophagus. In this case the pump consists of the muscles of the mouth and upper pharynx, the sphincter is the crico-pharyngeal sphincter and the resevoir is the esophagus. The second functional unit is responsible for the movement of the bolus from the esophagus into the stomach; the pump is the muscle of the esophagus 1, the sphincter is the lower esophageal sphincter and the resevoir the stomach.
When we drink a bolus of fluid and or food is placed in the mouth and swallowing starts with movement of the bolus from the mouth into the upper esophagus. The bolus then moves down through the esophagus, and through the lower esphageal sphincter into the stomach.