Dysphagia is the medical term for difficulty swallowing. There are typically four stages of dysphagia that can be used to assess the severity of the condition. These stages are:Oral preparatory stage: This stage involves the preparation of food or liquid in the mouth prior to swallowing. During this stage, the food is chewed and mixed with saliva to form a bolus that is ready to be swallowed.Oral stage: This stage involves the movement of the bolus from the front of the mouth to the back of the mouth, where the swallowing reflex is triggered.  In this stage, the tongue and other muscles in the mouth and throat work together to move the bolus toward the pharynx.Pharyngeal stage: This stage involves the movement of the bolus through the pharynx and into the esophagus.  During this stage, the larynx (voice box) closes to prevent food or liquid from entering the airway, and the muscles in the pharynx contract to push the bolus down into the esophagus.Esophageal stage: This stage involves the movement of the bolus through the esophagus and into the stomach. In this stage, the muscles in the esophagus contract in a coordinated manner to move the bolus downward toward the stomach.