Deglutition

Introduction

Deglutition is the process of swallowing. Food is passed from the oral pharynx into the oesophageal/laryngeal pharynx whilst the epiglottis closes across the entrance of the trachea.

It is an involuntary reflex preventing food from passing into the trachea and thus preventing choking and respiratory pneumonia.

Process

Masticated and insalivated food is cupped by the tongue on its dorsal surface and the tip of the tongue pushes dorsally against the soft palate.

The jaws are closed. The mylohyoid, hyoglossal and stylohyoid mucles raise the tongue and push the bolus into the oropharynx. When the food touches the pharyngeal mucosa, the swallowing reflex is initiated.

The Oropharynx relaxes and the soft palate is elevated by the levator velli palatini muscle. The pharyngeopalatine arch closes by the palatopharyngeus.

The Hyoid is moved rostro-dorsally and the pterygopharyngeus contracts bringing the common pharynx forward to engulf the bolus. The Epiglottis bends back to prevent food entering the larynx.

The bolus enters the laryngeal pharynx and the tongue relaxes. The bolus is passed on down the oesophagus by a concentric series of contractions by each set of contractor muscle in turn called peristalsis. The pharyngeopalatine arch reopens and the hyoid moves back by the geniohyoid. The glottis reopens.

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