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
1. 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
2. The jaws are closed. The mylohyoid, hyoglossal and stylohyoid mucles raises the tongue and pushes the bolus into the oropharynx. When the food touches the pharyngeal mucosa the swallowing reflex is initiated.
3. Oropharynx relaxes and soft palate elevated by the levator velli palatini muscle. Pharyngeopalatine arch closes by palatopharyngeus.
4. Hyoid moved rostro-dorsally by geniohyoid and pterygopharyngeus contracts bringing common pharynx forward to engulf bolus.
5. Epiglottis bends back to prevent food entering larynx.
6. Bolus enters laryngeal pharynx and tongue relaxes. Bolus is passed on down oesophagus by a concentric series of contractions by each set of contractor muscle in turn called peristalsis
7. Pharyngeopalatine arch reopens, hyoid moves back by geniohyoid and glottis reopens.