Physiology and pathophysiology of oropharyngeal dysphagia in older persons

Deglutition or swallowing is a complicated sensorimotor act that involves the activation of more than 30 pairs of muscles controlled by more than five cranial nerves to be completed in a coordinated and safe manner. Deglutition involves both voluntary and reflexive actions. Although historically, swallowing has been a reflex, the newest evidence demonstrates that swallowing is a highly coordinated sensorimotor response rather than a true reflex. For the patterned response called swallowing, there is not a specific area in the central nervous system that controls the action, as happens for a true reflex, and the completion of the motor output of the swallow is adaptable to factors that are present, such as bolus volume, viscosity, temperature, or even changes or alterations of anatomical nature. This chapter aims to describe swallowing physiology and its pathophysiology in older patients.