2 physiology-of-deglutition
TRANSCRIPT
Physiology of Deglutition
Dr. Vishal Sharma
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)
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
Oral preparatory stage
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
Oral propulsive stage
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)
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 (?)
Nasopharyngeal isthmus closed
Elevation & closure of Larynx
Oropharyngeal isthmus closed
Pharyngeal stage
5. Posterior retraction of base tongue:
tongue driving
force
6. Pharyngeal constrictors contract
7. Elevation of pharynx
8. Opening of cricopharyngeal sphincter
Tongue driving force
Contraction & elevation of pharynx
Opening of cricopharynx
Oesophageal stage1. 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
Closing of cricopharynx
Opening & descent of larynx
Oesophageal Peristalsis
Peristalsis
Intraluminal pressure changes
Bolus enters stomach
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
Recap
Oral preparatory stage
Oral propulsive stage
Nasopharyngeal isthmus closed
Elevation & closure of Larynx
Oropharyngeal isthmus closed
Tongue driving force
Contraction & elevation of pharynx
Opening of cricopharynx
Closing of cricopharynx
Opening & descent of larynx
Primary Peristalsis
Bolus enters stomach
Video-fluoroscopyLateral view
Oral propulsive stage
Larynx elevation
Closure of nasopharyngeal isthmus & larynx
Contraction of upper constrictor
Contraction of middle constrictor
Contraction of lower constrictor & relaxation of cricopharyngeal sphincter
Cricopharyngeal sphincter closes & larynx opens
Video-fluoroscopyAnterior view
Contrast enters oropharynx
Pyriform fossae fill symmetrically
Contrast reaches crico-pharyngeal sphincter
Cricopharynx opens & contrast enters esophagus
Constrictors squeeze all contrast into esophagus
No stasis
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)
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
Thank You