Pharyngeal Stage


The pharyngeal stage starts when the bolus reaches the valleculae, and ends when the bolus has entered the oesophagus (Groher & Crary, 2010). The following diagrams are representations of the bolus (the black areas) during the pharyngeal stage.




Pharyngeal.jpg



Further elevation of the hyoid, and airway protection


During the pharyngeal stage, the hyoid continues to elevate anteriorly, which in turn tilts the larynx under the retracted tongue base. This further prevents the bolus from entering the airway. During this stage, the airway is also protected by the approximation of the false vocal cords and the closure of laryngeal aditus by the aryepigottic folds (Groher & Crary, 2010).




Bolus transit in the pharynx


As the bolus enters the pharynx, the palatopharyngeus and stylopharyngeus contract to elevate and shorten the pharynyx (Groher & Crary, 2003). The superior, middle and inferior constrictor muscles also contract sequentially to create a peristalsis like motion that aids the bolus’ movement towards the oesophagus (Groher & Crary, 2010).

The bolus is divided once it reaches the epiglottis, and then diverted laterally around the laryngeal aditus via the pyriform fossa. The bolus is then rejoined as it enters the oesophagus (Groher & Crary, 2010).




The end of the pharyngeal phase


As the tail of the bolus passes into the oesophagus, the airway reopens, and the hyoid returns to its resting position. This in turn lowers the larynx, and raises the epiglottis to its erect position. The cricopharyngeus returns to its closed resting position, and primary oesophageal peristalsis commences (Groher & Crary, 2010).




References


Groher, M., & Crary, M. (2003). Introduction to adult swallowing disorders. Philadelphia, PA: Butterworth-Heinemann.


Groher, M., & Crary, M. (2010). Dysphagia: Clinical management in adults and children. Maryland Heights, MO: Mosby Elsevier.