Updated: 4/4/2015

Swallowing

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Oral Phase of Swallowing
  • Swallowing is under voluntary control in the mouth 
  • Propels the food bolus from the mouth to the pharynx
    • tongue forces the food bolus back towards the pharynx
      • activates the somatosensory receptors located near the pharynx
        • initiates involuntary swallowing reflex in the swallowing center in the medulla
Pharyngeal Phase of Swallowing
  • Swallowing is under involuntary ("reflex") control in the pharynx
  • Propels the food bolus from the pharynx to the esophagus
    • soft palate rises to prevent the food bolus from entering the nasopharynx
    • epiglottis covers the laryngeal opening to prevent the food bolus from entering the trachea 
    • upper esophageal sphincter relaxes and opens
      • allows the food bolus to move from the pharynx to the esophagus
    • peristaltic wave of contraction mediated by the swallowing reflex initiates in the pharynx and propels the food bolus from the pharynx, through the upper esophageal sphincter, into the esophagus
  • Breathing is inhibited during the pharyngeal phase of swallowing
Esophageal Phase of Swallowing
  • Swallowing is under involuntary ("reflex") control in the esophagus
  • Propels the food bolus from the esophagus to the stomach
    • food bolus is propelled from the pharynx, through the upper esophageal sphincter, and into the esophagus
    • once the food bolus enters the esophagus, the upper esophageal sphincter contracts and closes to prevent the food bolus refluxing into the pharynx
    • primary peristaltic wave of contraction mediated by the swallowing reflex involving a series of coordinated, sequential contractions propels the food bolus from the esophagus, through the cardiac sphincter (lower esophageal sphincter), and into the stomach
      • if the primary peristaltic wave of contraction does not clear the esophagus of food, a secondary peristaltic wave mediated by the enteric nervous system is initiated
 

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