Swallowing reflex

SWALLOWING REFLEX

  • Swallowing centre is located in the brain stem (medulla oblongata)
  • Stimulation of the receptors in the soft palate, pharynx (posterior wall) and epiglottis (dorsal surface) by food material initiate this reflex.
  • It is a complex multi synaptic reflex involving pharyngeal and oesophageal stage.
  • Sensory fibres pass through trigeminal, glossopharyngeal and vagus nerve.
  • This reflex involves internuncial neurons.
  • Efferent fibres emerge through glossopharyngeal, vagus and hypoglossal nerves which supply to the muscles of myohyoid and hypoglossal.
  • The muscles press the tounge against hard palate.
  • This causes the tounge to draw backward with the elevation of soft palate.
  • Now the tounge forces the bolus into opened oesophagus.
  • Opening of the oesophagus is by the pulling action of hyoid bone and layrnx.
  • As it happens the epiglottis closes so as to shut the layrnx.
  • Swallowing centre also activate through its efferent limb the neighbouring neurons that control respiration.
  • This interupts respiration during swallowing as a preventive measure to avoid aspiration of food particles into respiratory passage.

Last modified: Thursday, 9 June 2011, 5:30 AM