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2. physiology of deglutition

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physiology of deglutition

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2. physiology of deglutition

  1. 1. Physiology of Deglutition Dr. Vishal Sharma
  2. 2. Stages 1. Oral stage (lasts for 1 second, voluntary)  Preparatory phase  Propulsive phase 2. Pharyngeal Stage (1 second, involuntary) 3. Oesophageal Stage (8-20 seconds)
  3. 3. Oral preparatory stage • Not required for liquids • Solid food chewed, lubricated with saliva & converted to a bolus • Requires coordinated movement of lips, cheeks, jaws & tongue against a closed oropharyngeal isthmus
  4. 4. Oral preparatory stage
  5. 5. Oral propulsive stage • Food bolus propelled backwards by pressing of tongue against hard palate • Approximation of tongue against hard palate starts with tip of tongue & moves back • Stage ends when food bolus crosses anterior tonsillar pillar
  6. 6. Oral propulsive stage
  7. 7. Pharyngeal stage 1. Nasopharyngeal isthmus closed: soft palate touches Passavant’s ridge 2. Oropharyngeal isthmus closed: tongue base touches palate 3. Elevation of larynx: negative pressure in hypopharyngeal lumen (suction pump)
  8. 8. Pharyngeal stage 4. Closure of larynx: below upwards • True vocal cords approximate • False cords approximate • Ary-epiglottic folds approximate • Temporary cessation of respiration • Epiglottis falls back over larynx inlet (?)
  9. 9. Nasopharyngeal isthmus closed
  10. 10. Elevation & closure of Larynx
  11. 11. Oropharyngeal isthmus closed
  12. 12. Pharyngeal stage 5. Posterior retraction of base tongue: tongue driving force 6. Pharyngeal constrictors contract 7. Elevation of pharynx 8. Opening of cricopharyngeal sphincter
  13. 13. Tongue driving force
  14. 14. Contraction & elevation of pharynx
  15. 15. Opening of cricopharynx
  16. 16. Oesophageal stage 1. Closing of cricopharyngeal sphincter 2. Opening & descent of larynx 3. Primary peristalsis: large amplitude, propulsive 4. Secondary peristalsis: small amplitude, propulsive, for food remnants 5. Relaxation of lower esophageal sphincter: food bolus enters stomach
  17. 17. Closing of cricopharynx
  18. 18. Opening & descent of larynx
  19. 19. Oesophageal Peristalsis
  20. 20. Peristalsis
  21. 21. Intraluminal pressure changes
  22. 22. Bolus enters stomach
  23. 23. Neural Mechanism • Afferent: 5th , 9th & 10th cranial nerves • Deglutition centre: medulla oblongata • Efferent: 10th , 11th & 12th cranial nerves → tongue, pharynx, larynx & oesophagus muscles • Cessation of respiration: connection between deglutition & respiration centres in medulla
  24. 24. Recap
  25. 25. Oral preparatory stage
  26. 26. Oral propulsive stage
  27. 27. Nasopharyngeal isthmus closed
  28. 28. Elevation & closure of Larynx
  29. 29. Oropharyngeal isthmus closed
  30. 30. Tongue driving force
  31. 31. Contraction & elevation of pharynx
  32. 32. Opening of cricopharynx
  33. 33. Closing of cricopharynx
  34. 34. Opening & descent of larynx
  35. 35. Primary Peristalsis
  36. 36. Bolus enters stomach
  37. 37. Video-fluoroscopy Lateral view
  38. 38. Oral propulsive stage
  39. 39. Larynx elevation
  40. 40. Closure of nasopharyngeal isthmus & larynx
  41. 41. Contraction of upper constrictor
  42. 42. Contraction of middle constrictor
  43. 43. Contraction of lower constrictor & relaxation of cricopharyngeal sphincter
  44. 44. Cricopharyngeal sphincter closes & larynx opens
  45. 45. Video-fluoroscopy Anterior view
  46. 46. Contrast enters oropharynx
  47. 47. Pyriform fossae fill symmetrically
  48. 48. Contrast reaches crico-pharyngeal sphincter
  49. 49. Cricopharynx opens & contrast enters esophagus
  50. 50. Constrictors squeeze all contrast into esophagus
  51. 51. No stasis
  52. 52. Factors preventing reflux Anatomical: 1. Lower oesophageal sphincter contraction 2. Pinch cock action of right crus of diaphragm 3. Oblique esophageal entry into stomach 4. Lower esophageal mucosal folds (valvular)
  53. 53. Factors preventing reflux 5. Oblique gastric muscle around lower esophagus 6. Abdominal pressure > gastric pressure & intra- thoracic pressure Physiological: 1. Unidirectional esophageal peristalsis 2. Gastric emptying
  54. 54. Thank You

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