The document discusses the physiology of deglutition or swallowing. It describes how swallowing involves coordinated muscle activity to move food from the mouth to the stomach through three phases - oral, pharyngeal, and esophageal. The oral phase prepares food for swallowing through chewing and mixing with saliva. The pharyngeal phase is a reflex that protects the airway and involves tongue pumping and epiglottis closure. The esophageal phase relaxes the lower esophageal sphincter to allow food passage through peristalsis. Neural control involves both voluntary and involuntary pathways in the brain and medulla to coordinate the complex swallowing process.

1. Physiology of
deglutition
Dr. Roohia

2. 2
Introduction
• Deglutition involves co-ordinated
activity of muscles of oral cavity,
pharynx, larynx and esophagus
• The whole process is partly under
voluntary control & partly
reflexive in nature
• Deglution by definition involves
passage of bolus of food (solid /
liquid) from the oral cavity to
stomach via the pharynx and
esophagus.
• Voluntary control of deglutition
involves control of jaw, tongue,
degree of constriction and length
of pharynx and closure of
laryngeal introitus

3. 3
Components of deglutition
•
•
•
•
Deglution has 3 components
Passage of bolus from oral cavity to stomach
Protection of airway
Inhibition of air entry into the stomach

4. 4
Deglutition - phases
• Oral
• Pharyngeal
• Esophageal
These stages have been traditionally described for
the sake of convenience. They help in the better
understanding of the physiological process
involved.

5. 5
Oral phase
• In this phase food is prepared
for swallowing
 Tongue plays a vital role in this
process
• This phase is divided into oral
preparatory phase and oral
phase proper
• This phase is vital in all land
animals which don’t swallow
their food as a whole
• This phase is under voluntary
control

6. Oral preparatory phase
• This phase involves breaking down
of food in the oral cavity
• During this phase the food is
chewed and mixed with saliva
making it into a bolus which can be
swallowed
• The elevators of lower jaw play an
important role in bolus preparation
• Tongue plays a vital role in bolus
formation by the action of its
intrinsic muscles which alters its
shape. Its extrinsic muscles
changes its position within the oral
cavity thereby helping in chewing
the food by dental occlusion
• Occlusal action of the lips help in
creating an effective seal preventing
the bolus from dribbling out of the
oral cavity
• The action of buccinator muscle
helps in pushing the bolus out of the
vestibule into the oral cavity proper
6

7. 7
oral preparatory phase (contd)
• SALIVARY GLANDS:
 Salivary glands connected to
mouth by ducts.
 Glands produce saliva.
 Saliva contains:
 Mucin- holds food together.
 Salivary amylase- starts
digesting carbohydrates.
 Bicarbonates-maintain PH
level of saliva&protect teeth.
 Lysozymes-inhibits
bact.,growth.

8. 8
Bolus formation
• This is the most important
function of preparatory phase
• This involves repeated transfer
of food from oral cavity to
oropharyngeal surface of
tongue
• Bolus accumulates on the
oropharyngeal surface of
tongue due to repeated cycles
of upward & downward
movement of the tongue

9. Oral phase proper
• During this phase the bolus is moved
towards the back of the tongue
• The contraction of soft palate prevents
nasal regurgitation
• The soft palate also prevents
premature movement of bolus into the
oropharynx
• Once the bolus is of suitable
consistency the transit from mouth to
oropharynx just takes a couple of
seconds
• Tongue plays a vital role during this
phase. Its intrinsic muscles contracts
and reduces its size, while genioglossus
muscle elevates the tongue towards the
palate
• The elevation of the mandible plays a
vital role here
• When the mandible is elevated the
suprahyoid muscles raises the hyoid
bone
9

10. 10
Pharyngeal phase (Pumping action of
tongue & hypopharyngeal suction)
• This phase of deglutition is reflexive in
nature
• It is during this phase that Ventilatory
and alimentary streams cross each other.
Dynamic separation of these streams is
possible due to the co-ordination of reflex
phase that occurs
• It just takes a second for the bolus to
traverse the pharynx and reach the
cricopharyngeal area
• Contraction of diaphragm is inhibited
making simultaneous breathing &
swallowing impossible
• Soft palate is elevated in order to seal off
the nasopharynx (T. palatini & L. palatini)
• Vocal cords adduct protecting the airway
• As the bolus passes the palatoglossal &
palatopharyngeal folds the act of
swallowing becomes reflexive

11. 11
Functions of trigger points
in oropharynx
• Stimulation of trigger points present
in the oropharynx starts off the
pharyngeal reflexive stage of
swallowing
• Trigger points are present at the
faucial arches & mucosa of the
posterior pharyngeal wall
• These trigger points are innervated
by glossopharyngeal nerve
• Stimulation of these trigger points
causes dilatation of pharynx due to
relaxation of the constrictors, and
elevation of pharynx & larynx due to
contraction of longitudinal muscles
• The pharynx constricts behind the
bolus thereby propelling it
• Contraction of the inferior constrictor
moves the bolus towards the
oesophagus

12. 12
Importance of laryngeal elevation
during pharyngeal stage
• It narrows the laryngeal inlet
• It ensures better sealing of the
laryngeal inlet by the downturned
epiglottis
• Laryngeal elevation also contributes
to dilatation of pharynx
• The laryngeal inlet is closed due to
the actions of interarytenoid,
aryepiglottic and thyroepiglottic
muscles

13. 13
Role of epiglottis in the pharyngeal
phase
• The movement of epiglottis occurs
in two stages
• The epiglottis moves from vertical
– horizontal position
• The upper third of epiglottis moves
below the horizontal to a slightly
lower level to cover the narrowed
laryngeal inlet
• The bolus during the course of the
swallow impinges on the epiglottis
and gets diverted to the lateral food
channels
• Solid food tends to go behind the
epiglottis in to the post cricoid area
• Liquid food gets split by the
epiglottis and passes via the
pyriform fossae

14. 14
Esophageal stage
• This is purely reflexive
• This phase begins by relaxing
the cricopharyngeal sphincter
• The time taken for esophageal
transit is 10-15 seconds
• Primary / secondary / tertiary
peristaltic waves play active
roles in this phase

15. 15
Neural control of swallowing
• Two areas of brain are
involved
• Cerebral cortex
• Brain stem

16. 16
Neural control (initiation)
• Initiation of swallow is voluntary
• Bilateral prefrontal, frontal and
parietal cortices are involved
• Swallowing is initiated when food
comes into contact with certain
trigger areas like fauces / mucosa
of posterior pharyngeal wall
• Afferent nerve is the
glossopharyngeal nerve
• Nucleus tractus solitarius &
spinal nucleus of trigeminal nerve
play a vital role
• Efferents involve several cranial
nerve nuclei which include
nucleus ambiguus (muscles of
palate, pharynx and larynx),
hypoglossal nucleus supplying the
muscles of the tongue, motor
nuclei of trigeminal and facial
nerves supplying the muscles of
face, jaws and lips.

17. 17
Role of medulla
• There are two groups of neurons
in the medulla while lie between
the afferent and efferent system
• First group lie in the dorsal
medulla above the nucleus of
the solitary tract
• The second group lie in the
ventral medulla around nucleus
ambiguus
• These groups of neurons are
named as lateral & medial
medullary swallowing centers

18. 18
Role of central pattern generator
• Central pattern generator
are a set of neurons capable
of initiating sequential
swallow
• These neurons act like a
cardiac pacemaker
• Since the process of
swallowing and breathing
are interlinked there is a
certain degree of central co
ordination taking place

19. 19
Phase of respiration & swallowing
• Swallowing occurs during expiratory phase of
respiration
• This helps in clearing food material left in the
vestibule. Thus it should be considered to be a
protective phenomenon
• The rhythm of respiration is reset after a
successful swallow

20. 20
STUDY OF SWALLOWING

21. 21
INDICATIONS FOR STUDY OF
SWALLOWING

22. 22
STUDY OF SWALLOWING

23. 23
Fluroscopic imaging of swallowing

24. 24

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32. 32
Double contrast image of pharynx

33. 33
Examination of oesophagus

34. 34
Dc image of gastro oesophageal
junction

35. 35
Analysing disorders of swallowing

36. 36
asymmetry

37. 37
Stasis

38. 38
Cricopharyngeal dysfunction

39. 39
drtbalu's otolaryngology
online

40. 40
drtbalu's otolaryngology
online

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drtbalu's otolaryngology
online

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drtbalu's otolaryngology
online

43. 43
drtbalu's otolaryngology
online

44. 44
drtbalu's otolaryngology
online

45. 45
Aspiration

46. 46
Web

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