Deglutition/ dental implant courses

SEMINAR ON DEGLUTITION
1 INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

LEARNING OBJECTIVES:
 At the end of the session learner should be able to;
1. Describe the phases of deglutition.
2. Explain the neuronal control of deglutition.
3. Describe the importance of act of deglutition.
4. Enumerate various pathological conditions
affecting deglutition.
5. Applied aspect of deglutition.
2

CONTENTS
 Introduction
 Stages of deglutition with their mechanisms
 Lower eosophageal sphincter
 Neural control of deglutition
 Applied aspect of diglutation.
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DEFINITION :
 Is defined as act of swallowing
 Swallowing is controlled by a central program generator
in the medulla.
 It is initiated by the voluntary act of propelling what is in
the mouth towards the back of the pharynx and involves
carefully timed responses of the respiratory as well as the
gastrointestinal system.
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 This starts a wave of involuntary contraction in the
pharyngeal muscles that pushes the material into
esophagus.
 Inhibition of respiration and glottic closure are part
of the reflex response.
 A peristaltic ring contraction of the esophageal
muscles forms behind the materials, which is the
swept down the esophagus at the speed of
approximately 4 cm/s.
 When humans are in an upright position, liquids
and semisolid food generally fall by gravity to the
lower esophagus ahead of the peristaltic wave. 5

 A normal adult swallow frequently while eating but
swallowing also continues between meals.
 The total number of swallows per day is about 600.
 200- while eating
 350- while awake without food
 50- while sleeping.
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 Involves an ordered sequence of events that carry
food from mouth into the stomach.
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IMPORTANCE
 Alongwith the Muscle movements side by side,also
mechanisms to control and protect the airway are
carried out.
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During deglutition, the
muscles of mouth, pharynx,
larynx and esophagus
coordinate properly in a
process; to move food and
liquid into stomach.
 The airway is protected
by correct movement of
larynx, so that food and
liquid not enter the airway
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ORGANS OF DEGLUTITION
• Oral cavity
• Pharynx
– (Nasopharynx)
– Oropharynx
– Laryngopharynx
• Larynx
• Esophagus
• Stomach
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11

12

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STAGES OF DEGLUTITION

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ROLE OF DIFFERENT MUSCLES
 Massetor and Temporalis muscles: Firstly, elevate
the jaw.
 Circumoral muscles : approximate the lips to form
the anterior seal.
 Styloglossus ,& Genioglossus muscle : produces a
longitudinal furrow is produced on the dorsal
surface of the tongue.
 Mylohyoid muscle: help to elevate tongue 15

INTRINSIC MUSCLES OF TONGUE
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17

INTERPLAY OF HYOID BONE AND MUSCLES
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IS A VOLUNTARY ACTION
 With this movments, the bolus empties from the
oral cavity by the tongue towards the pharynx.
 At this stage the airway remains open, as soft
palate is away from the posterior wall of pharynx.
 The soft palate : forms posterior seal, by contacting
the posterior surface of the tongue.
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AT THE END OF 1ST STAGE
 Suprahyoid muscles : move the hyoid bone upwards
and forwards.
 Palatoglossi : approximate the palatoglossal arches.
 Styloglossus : help to elevate the tongue upwards
and backwards.
 All this actions help to move the bolus through the
oropharyngeal isthmus to the oropharynx to begin
the 2nd stage……………..
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SECOND STAGE OF DEGLUTITION
 Is involuntary and rapid
 Entire process occurs in less than 2
seconds
 Starts from the point at where the
deglutition reflex is triggered at the
anterior faucial arch through the
upper esophageal sphincter into the
esophagus.
 The bolus is propelled by pumping
action of tongue base and
constriction of Pharyngeal muscles 22

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•Soft palate is elevated, sealing off the nasopharynx from oropharynx, prevent
reflux of food into nasal cavity
• Initiation of pharyngeal peristalsis to pick up and carry the bolus
• Elevation and closure of larynx, to prevent food from entering airway
• Upper esophageal sphincter (cricopharyngeus muscle) relaxation

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25
 Larynx is pulled upward and anteriorly by muscles of neck, cause
epiglottis to swing backward over the opening of larynx.
Closure of larynx at all 3 sphincters
• Epiglottis / aryepiglottic folds
• False vocal folds
• True vocal folds
Cessation of respiration
Larynx is closed off to the bolus by several mechanisms:

THIRD STAGE OF DEGLUTITION
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 It is also involuntary – 8-20
seconds transmit time
 Starts from the point where
the bolus enters the
esophagus at the upper
esophageal sphincter , Until
the bolus passes into
stomach at the lower
esophageal sphincter

ESOPHAGEAL STAGE
 Esophagus has two sphincters :
1. Upper : situated at the upper end of the
esophagus
2. Lower : lower eosophageal sphincter (LES),
situated where the eosophagus opens the
stomach.
 Normally both the sphincters are closed.
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END OF THE 2ND STAGE
 Upper sphincter opens
 Bolus enters the esophagus
 Sphincter gets closed
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29

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 A wave of peristalsis is initiated at
the upper end of the esophagus
which travels downwards and
causes the bolus to move
downwards.
 The food bolus reaches the lower
end of the esophagus
 LES relaxes and the bolus is moved
into the stomach.
 As the food reaches the stomach,
LES gets closed ending the process
of deglutition.

LOWER ESOPHAGEAL SPHINCTER
(GASTROESOPHGEAL JUNCTION)
 Unlike the rest of esophagus, the musculature of the
LES is tonically active but relaxes on swallowing.
 The tonic activity prevents the highly acidic gastric juices
to enter the esophagus and thus prevents esophageal
mucosa from any damage .
 the tone of LES is under neuronal control. Vagal endings
cause it contract and relax.
 Phrenic nerve, is coordinated with respiration and
contraction of chest and abdominal muscles.
 Thus , the intrinsic and extrinsic sphincters operate
together to permit orderly flow of food into the stomach
and to prevent reflux of gastric contents into esophagus.
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NEURAL CONTROL
 The first act of deglutition is voluntary.
 The whole process is a reflex act.
 The receptors for swallowing in human beings are
situated in the pharynx and in adjacent regions.
 Center of deglutition is situated near the medullary
portion of respiratory center.
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 Swallowing (deglutition) is a reflex response that is
trigered by afferent impulses in the trigeminal,
glossopharyngeal and vagus nerve.
 These impulses are integrated in the nucleus of the
tractus solitarious and the nucleus ambiguus.
 The efferent fibres pass to the pharyngeal musculature
and the tongue via the trigeminal, facial, and
hypoglossal nerve.
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DEGLUTITION REFLEX
 • Deglutition reflex is mainly a
protective reflex
2 main things take place during
reflex
 A squeezing action squeezes the
bolus with muscles that pull food
down to the stomach. This action
is called peristalsis.
 Larynx closes off to keep food out
of the airway,The epiglottis folds
down & the vocal folds shut.
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DEGLUTITION REFLEX
36
 Sensory impulses reach the
deglutition center deglutition
center in brain stem
 Motor function is mediated
through the 5th, 9th, 10th and
12th cranial nerves
 To initiate muscle
contraction
– Elevation of soft palate
– Elevation and closure of
larynx
– Peristalsis of pharynx and
esophagus.

APPLIED ASPECT OF DEGLUTITION:
 Difficulty of deglutition is known as DYSPHAGIA.
 Deglutition can be restricted if the muscle of the mouth,
pharynx, larynx or esophagus are weak or uncoordinated.
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 Tongue dysfunction – prevent normal bolus movement
through the oral cavity
 Palatal dysfunction – nasal regurgitation during deglutition.
 Dysfunction of pharyngeal constrictors
• poor bolus propulsion through pharynx
• Pooled bolus can then easily spill over into larynx
38

 Dysfuction of larynx – can cause aspiration. If larynx
does not close off and tilt out of the way at the right
moment, food or drink may get into airway.
 Dysfunction of upper esophageal sphincter - lead to
difficult passing from pharynx into esophagus.
 Deglutition problem can lead to coughing, airway
obstruction,pneumonia and even death.
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ACQUIRED CENTRAL DISORDERS
 Stroke syndromes or vascular disorders
 Movement disorders : parkinsonian disease
 Poliomyelitis
 Other : tuberculosis
syphilis
neoplasms
degenerative disorders
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ACQUIRED PERIPHERAL DISORDERS
 Recurrent laryngeal neuropathy
 Cranial neuropathies like : Diabetes
leukaemia,
carcinoma
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 Acquired inflammation
 Trauma
 Neurodevelopmental disorders like Cerebral palsy
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 Motor disorder of esophagus
- Achalasia-
- Is a condition in which food accumulates in the
esophagus and the organ becomes massively
dilated
- It is due to increase resting lower esophageal
sphincter tone and incomplete relaxation on
swallowing.
- It can be treated by pneumatic dilation of the
spincter or incision of the esophageal muscles
(myotomy)
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 Gastroesophageal reflux disease:
Condition of LES incompetance which permits reflux
of acid gastric contents into the esophagus.
This common condition causes heartburn and
esophagitis and can lead to ulceration and
strincture of the esophagus due to scarring.
The condition can be treated by inhibition of acid
secretion with H2 receptor blockers or omeprazole.
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CONCLUSION:
Essential requirements of deglutition
 Preparation of suitable size and consistency of bolus
 Prevention of bolus disperse during various phases of
deglutition
 Create pressure to propel bolus in forward direction
 Prevention of bolus to enter nasopharynx and larynx
 During Rapid passage through pharynx to esophagus ,stop
breathing
 Many times food particles may enter accidentally in to air
way, instant coughing reflex may prevent it to move forword.
 But it may be a medical emergency. 45

 Deglutition is generally safest when the person is
sitting straight, with head upright or slightly forward
 Must be awake and alert, without distractions such
as television
 Allow more time to eat and drink
 Always make sure that one mouthful has gone
before offering the next
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REFERENCES :
 William F. Ganong; Review of medical physiology,
23rd edition, Tata McGrave-Hill edition.
 Prema Sembullingham; Essentials of Medical
Physiology, 2nd edition, Jaypee Publication.
 B.D.Chaurasia; human anatomy for medical
students, 6th edition.
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Greatest of all the professions known to mankind is
teaching.
Parents give life
but teachers keep it alive.
Words cannot express all the feelings ,
But only thing we can say is
II Tasmay Shree Guruve Namaha II
Happy teachers day.
48

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