clack valve: a simple valve with a hinge on one side; allows fluid to flow in only one direction
valve: control consisting of a mechanical device for controlling the flow of a fluid
oculopharyngeal muscular dystrophy: a form of muscular dystrophy that usually begins between early adulthood and middle age and first affects muscles of the eyelid and throat; progresses slowly with swallowing problems common as the disease progresses; inheritance is autosomal dominant