Swallowing(Deglutition). Voluntary Stage (oral stage) This initiates the swallowing process Involuntary Pharyngeal stage This is involuntary and constitutes passage of food through pharynx into esophagus. Esophageal stage
This initiates the swallowing process
This is involuntary and constitutes passage of food through pharynx into esophagus.
This is also involuntary phase that transports food from the pharynx to the stomach
Food is voluntarily squeezed or rolled posteriorly into the pharynx by pressure of the tongue upward and backward against the palate.
When the bolus enters the posterior mouth and pharynx it stimulates epithelial swallowing receptor areas all around the opening of pharynx and impulses from these pass to the brain stem to initiate a series of automatic pharyngeal muscle contractions.
Once the larynx is raised and the pharyngo esophageal sphincter becomes relaxed the entire muscular wall of pharynx contracts beginning in superior part and then spreading downward which propels the food by peristalsis into esophagus.
Impulses go through the sensory portions of trigeminal nerve and glossopharyngeal nerve to the swallowing center in the lower pons and medulla
The motor impulses from the swallowing center go through the fifth, ninth, tenth and twelfth cranial nerves to the pharynx and esophagus.
The entire pharyngeal stage of swallowing occurs in less than 6 seconds.
The tonic contraction of LES prevents the reflux of stomach contents into the esophagus.