Critical Factors in the Oral Control Needed for Chewing and Swallowing.

Normal oropharyngeal swallowing is a complex set of neuromotor behaviors containing three phases: 1) Oral preparation to break food down to a swallowable consistency; 2) Oral phase which propels food from the mouth; 3) Pharyngeal phase creates pressure to push food into the esophagus, and includes valve functions which prevent food from entering the nose or airway and allow food into the esophagus. Systematic changes in normal oropharyngeal swallow are based on volume, viscosity, and taste of the food swallowed as well as age. Patients with oropharyngeal swallowing difficulties (dysphagia) react differently to these systematic variables in food characteristics. This review manuscript presents the results of a series of studies that examine the role of each of the stages of the nonoral orpharyngeal swallow. The importance of the definition of food viscosity in the care of dysphagic patients and the role of food production companies in this effort are emphasized.