Pharyngeal Stage (pharyngeal swallow)
complex sequence of reflexively controlled events. bolus reaches faucial pillar region(move medially)/ posterior base initiating pharyngeal swallow. soft palate elevates, oropharynx now separated from nasopharynx. protective function: vocal folds tightly adduct, constriction of false vocal folds, epiglottis depresses(via aryepiglottis muscles), larynx elevates relative to tongue(hyoid bone is palpable). cricopharyngeus muscle of inferior constrictor relaxing by portion of laryngeal nerve of vagus that innervates its state of tonic(continuous) contraction. upper esophageal sphincter(UES) continually contracts till swallow is initiated- keeps gastic contents from escaping into laryngopharynx. food is propelled down superior, middle, then inferior pharyngeal constrictors. bolus divides into 2 recombining at esophageal entrance.