Refers to failure of the tonically contracted [intlink id=”615″ type=”post”]upper esophageal sphincter[/intlink] (UES) to relax and open when one swallows. Cause is usually unknown. The UES comprises the [intlink id=”113″ type=”post”]cricopharyngeus muscle[/intlink] and is located at the lower level of the voicebox or larynx. Typically, individuals with CPD first notice that pills or solid food begin to lodge at the level of the larynx. The problem tends to progress inexorably, though often slowly, as the years pass, until the individual must limit himself or herself to liquid and soft foods. This condition is fully resolved through a straightforward surgical procedure performed through the mouth with the laser and only occasionally through a neck incision. See also [intlink id=”701″ type=”post”]Zenker’s diverticulum[/intlink].