Swallowing and its Phases

Swallowing

• Swallowing, also known as deglutition, is the process of passing food, drink, etc. through the mouth to the stomach by means of the pharynx and into the esophagus, while shutting the epiglottis.

Phases of Swallowing

• There are three stages of swallowing:
  • Oral/buccal stage: voluntary
  • Pharyngeal stage: involuntary
  • Esophageal stage

Oral/Buccal Stage of Swallowing

• Initiated by contraction of muscles of tongue and floor of mouth
• Pushes the bolus posteriorly to the pharynx

Pharyngeal Stage of Swallowing

• Involuntary stage
• Swallowing receptors around tonsillar pillars convey impulses to the brainstem (pons & medulla oblongata)
• Causes pharyngeal muscle contractions, including:
  • Upward movement of soft palate
  • Closure of posterior nares
  • Medial approximation of palatopharyngeal folds
  • Tight approximation of vocal cords
  • Larynx pulled upward and anteriorly by neck muscles
  • Epiglottis covers opening of larynx
  • Pharynx contracts and food propelled into esophagus
• Swallowing center inhibits respiration during this phase

Esophageal Stage of Swallowing

• Starts with relaxation of upper esophageal sphincters
• When food passes, the sphincters close, glottis opens, and breathing resumes
• Food traverses the esophagus in about 6-10 seconds
• Two types of peristaltic movements in the esophagus:
  • Primary peristalsis: continuation of pharyngeal peristaltic movement
  • Secondary peristalsis: from distention of esophagus by retained food

Clinical Significance

• Gastroesophageal reflux disease can damage the esophagus, causing heartburn
• Dysphagia means ineffective swallowing

This quiz covers the process of deglutition, including the three stages of swallowing: oral, pharyngeal, and esophageal.