Deglutition

1. DEGLUTITION
Rishikesh Kurdukar
1stYear PG

2. Contents
 Introduction
 Physiologic events in swallowing
 Neural control of swallowing
 Swallowing Patterns
 Conditions causing defective swallowing
 Treatment of abnormal swallowing patterns
 Conclusion
 References

3. Introduction
 Deglutition(Swallowing) is a complicated
mechanism, principally because the pharynx
subserves respiration as well as swallowing.
 The pharynx is converted for only a few seconds at a
time into a tract for propulsion of food. It is especially
important that respiration not be compromised
because of swallowing.
 Swallowing is both an alimentary and a protective
reflex as it can be initiated by a bolus in the pharynx
and by chemical stimulation of water in the larynx.

4.  Three essential features of swallowing are-
 1.)Establishment of pressure gradient
 2.)Prevention of reflux
 3.)Protection of the airway
 Muscles responsible for swallowing show
“ALL OR NONE LAW” and that too in a proper
sequence that are said to be Obligatory muscles
while those not always taking part in the
sequence are Facultative muscles

7.  Facultative muscles-
-Sensitive to the feedback from the teeth
-May or may not participate in swallowing
-Used when there is an increased demand of establishing an
anterior oral seal like in case of absence of teeth, improper
occlusion causing improper anterior seal or even swallowing
solid bolus.
-While obligatory muscles are programmed prior to birth and
incapable of conditioning, the facultative muscles adapt to
naturally occuring stimulus

8. Physiologic Events of
Swallowing(Deglutition)
 The Normal swallowing Pattern in Infants is
different from that seen in adults.
 Thus there two types of Normal swallows-
 1.)Normal Infantile Swallow
 2.)Normal Mature Swallow
 Normal Infantile Swallow can be present till
age 3 to 6

9.  Normal Infantile Swallow
 Process of suckling- Nipple is drawn in to the
mouth by negative pressure- The tongue lies
over the lower gum pads- Milk is directed by an
automatic peristaltic movement of tongue and
mylohyoid muscle through the faucial pillars and
the lateral channels of the pharynx- Any excess
milk in the mouthbdribbles down the chin

10.  Characteristics of Infantile Swallow-
 1.)The Jaws are apart and the tongue is placed
between the lower and the upper gum pads.
 2.)The mandible is stabilised by the contraction
of the muscles of the seventh cranial nerve and
the interposed tongue.
 3.)The swallow is guided and to a large extent is
controlled by sensory interchange between the
lips and the tongue.

11.  Normal Mature swallow can be divided into
 There is Preparatory Phase before the
swallowing starts
 (1) a voluntary stage, which initiates the
swallowing process
 (2)a pharyngeal stage, which is involuntary and
constitutes passage of food through the pharynx
into the esophagus and
 (3) an esophageal stage, another involuntary
phase that transports food from the pharynx to
the stomach.

12.  Preparatory Phase
 Teeth are parted a little and the cheek muscles
contract after masticated food is assembled as a
compact bolus on the dorsum of the tongue
 Teeth are then brought into occlusion to stabilise
the jaws and close the oral cavity to isolate it.
 The posterior aspect of the tongue is pressed
against the soft palate.

14.  Voluntary(Oral) Stage of Swallowing
 When the food is ready for swallowing, it is
“voluntarily” squeezed or rolled posteriorly into
the pharynx by pressure of the tongue upward
and backward against the palate,
 Later swallowing becomes entirely—or almost
entirely—automatic and ordinarily cannot be
stopped.

17. Pharyngeal Stage of Swallowing-
Time- Less than 6 seconds
Changes in-
-soft palate
-palatopharyngeal folds
-Larynx
-Upper esophageal sphincter(Pharyngo-esophageal
sphincter)

20. Pharynx from posterior aspect Change in the vocal cord

21. Effect of the Pharyngeal Stage of Swallowing on
Respiration.
 The entire pharyngeal stage of swallowing usually
occurs in less than 6 seconds, thereby interrupting
respiration for only a fraction of a usual respiratory
cycle.
 The swallowing center specifically inhibits the
respiratory center of the medulla during this time,
halting respiration at any point in its cycle to allow
swallowing to proceed. Yet, even while a person is
talking, swallowing interrupts respiration for such a
short time that it is hardly noticeable.

22. Esophageal Stage of Swallowing-
Primary Peristalsis- 8-10 seconds
Secondary peristalsis-

26. Neural control of swallowing
Degree of representation of
the different muscles of the
body in
the motor cortex.
Representation of the different
muscles of the body in the motor
cortex and location of other cortical
areas responsible for specific
types of motor movements.

27.  Swallowing mechanism.

28.  Sequence of pathway in
Pharyngeal Phase-
 Tonsillar pillars-
 trigeminal and
glossopharyngeal nerves-
 medulla oblongata-
 tractus solitarius(swallowing
center)-
 transmission successively by
the 5th, 9th, 10th, and 12th
cranial nerves and even a few
of the superior cervical nerves
that cause swallowing

29. Esophageal Stage-
 When Primary Peristalsis fails to transmit food to
the stomach the secondary peristaltic waves are
initiated partly by intrinsic neural circuits in the
myenteric nervous system and partly by reflexes
that begin in the pharynx and are then
transmitted upward through vagal afferent fibers
to the medulla and back again to the esophagus
through glossopharyngeal and vagal efferent
nerve fibers.

30.  The musculature of the pharyngeal wall and upper third of
the esophagus is striated muscle. Therefore, the peristaltic
waves in these regions are controlled by skeletal nerve
impulses from the glossopharyngeal and vagus nerves. In
the lower two thirds of the esophagus, the musculature is
smooth muscle, but this portion of the esophagus is also
strongly controlled by the vagus nerves acting through
connections with the esophageal myenteric nervous system.
 When the vagus nerves to the esophagus are cut, the
myenteric nerve plexus of the esophagus becomes excitable
enough after several days to cause strong secondary
peristaltic waves even without support from the vagal
reflexes. Therefore, even after paralysis of the brain stem
swallowing reflex, food fed by tube or in some other way into
the esophagus still passes readily into the stomach.

31.  Receptive Relaxation of the Stomach-
 When the esophageal peristaltic wave approaches
toward the stomach, a wave of relaxation,
transmitted through myenteric inhibitory neurons,
precedes the peristalsis. Furthermore, the entire
stomach and, to a lesser extent, even the duodenum
become relaxed as this wave reaches the lower end
of the esophagus and thus are prepared ahead of
time to receive the food propelled into the
esophagus during the swallowing act.

32.  Function of the Lower Esophageal Sphincter
(Gastroesophageal Sphincter).
 At the lower end of the esophagus, extending upward
about 3 centimeters above its juncture with the
stomach, the esophageal circular muscle functions as a
broad lower esophageal sphincter, also called the
gastroesophageal sphincter. This sphincter normally
remains tonically constricted with an intraluminal
pressure at this point in the esophagus of about 30 mm
Hg, in contrast to the midportion of the esophagus,
which normally remains relaxed. When a peristaltic
swallowing wave passes down the esophagus, there is
“receptive relaxation” of the lower esophageal
sphincter ahead of the peristaltic wave, which allows
easy propulsion of the swallowed food into the stomach.

33. Swallowing Patterns
 To understand various swallowing patterns we
need to examine properly if the patient has any
abnormal swallowing behavior.
 Examination of Swallow
 Unconscious Swallow
 Normal Mature Swallow
 Hand over the temporalis muscle
 Placement of tongue depressor
 Unconscious swallow

34.  As given by Moyers there are five types of
swallowing patterns-
1.)Normal Infantile Swallow
2.)Normal Mature Swallow
3.)Simple Tongue-Thrust Swallow
4.)Complex Tongue-Thrust Swallow
5.)Retained Infantile Swallow
Retained Infantile swallow is present in only brain
damage children hence is very rare

35.  Simple Tongue-Thrust Swallow
 Contractions of facultative
muscles
 Teeth-together swallow
 Tongue thrust present to seal the
open bite caused by some other
etiology like thumb-sucking
 Secure intercuspation
 Diminishes with age and
prognosis is good

36.  Complex Tongue-Thrust Swallow
 Teeth-apart Swallow
 Open bite more diffuse and
difficult to define
 Poor occlusal fit and instability of
intercuspation
 Test patient’s unconscious
swallow
 More often mouth breathers or
other respiratory diseases
 Does not diminish with age

37.  Retained Infantile Swallow
 Tongue thrusts between the teeth
 Contractions of Buccinator muscle
 Inexpressive faces
 Only one molar occlusion in each
quadrant
 Mastication between tongue and
palate
 Prognosis is very poor for these
patients
 Excessive anterior facial height
producing severe frontal open bite

38.  Differential Diagnosis of Swallowing types-

39. Conditions causing defective
Swallowing
 Paralysis of the Swallowing Mechanism.
-Paralysis of nerves
-Diseases like Encephalitis, Poliomyelities
-Signs of defective swallowing
 (1) complete abrogation of the swallowing act so
 that swallowing cannot occur,
 (2) failure of the glottis to close so that food passes
 into the lungs instead of the esophagus, and
 (3) failure of the soft palate and uvula to close the posterior nares
so that food refluxes into the nose during swallowing.

40.  One of the most serious instances of paralysis of
the swallowing mechanism occurs when patients
are under deep anesthesia. Often, while on the
operating table, they vomit large quantities of
materials from the stomach into the pharynx;
then, instead of swallowing the materials again,
they simply suck them into the trachea because
the anesthetic has blocked the reflex
mechanism of swallowing. As a result, such
patients occasionally choke to death on their own
vomitus.

41.  Achalasia
 Achalasia is a condition in which the lower esophageal
sphincter fails to relax during swallowing. As a result,
food swallowed into the esophagus then fails to pass
from the esophagus into the stomach
 Cause- damage in the neural network of the myenteric
plexus in the lower two thirds of the esophagus
 the musculature of the lower esophagus remains
spastically contracted, and the myenteric plexus has lost
its ability to transmit a signal to cause “receptive
relaxation” of the gastroesophageal sphincter as food
approaches this sphincter during swallowing.

42.  Megaesophagus
When achalasia becomes severe, the esophagus often cannot
empty the swallowed food into the stomach for many hours,
instead of the few seconds that is the normal time. Over
months and years, the esophagus becomes tremendously
enlarged until it often can hold as much as 1 liter of food,
which often becomes putridly infected during the long
periods of esophageal stasis. The infection may also cause
ulceration of the esophageal mucosa, sometimes leading to
severe substernal pain or even rupture and death.
Considerable benefit can be achieved by stretching the lower
end of the esophagus by means of a balloon inflated on the
end of a swallowed esophageal tube. Antispasmotic drugs
(drugs that relax smooth muscle) can also be helpful.

43.  Cretinism
 Skeletal growth in the child with cretinism is
characteristically more inhibited than is soft tissue
growth. As a result of this disproportionate rate of
growth, the soft tissues are likely to enlarge
excessively, giving the child with cretinism an obese,
stocky, and short appearance. Occasionally the
tongue becomes so large in relation to the skeletal
growth that it obstructs swallowing and breathing,
inducing a characteristic guttural breathing that
sometimes chokes the child.

44. Treatment of abnormal
Swallowing Patterns
 Simple tongue thrust swallow
 If there is excessive labioversion of the maxillary incisors,
treatment of the tongue thrust should not begin until
the incisors have been retracted.
 Steps in the treatment-
 Acquaint the patient to understand the normal
swallowing pattern.
 Reinforce it to subconscious level
 A well adapted soldered lingual archwirehaving short ,
sharp spurs

46.  Complex Tongue thrust Swallow
 Two problems- Abnormal occlusal reflex and abnormal
swallowing pattern
 Patient should be made aquainted with the severe problem of
his/her.
 Occlusion is treated first, careful occlusal equilibration is done.
 Then the muscle training exercise begins
 Orthodontic treatment is prolonged so that the patient gets
enough time to adapt to newly formed reflex.
 A maxillary lingual archwire with short , sharp spurs may be
used as a retainer.
 Though the patient has mastered the new reflex , lingual
archwire is placed
 There is always some amount of relapse

47.  Retained Infantile Swallow
 Occlusion on one molar in each quadrant
 No proper treatment for retained infantile
swallow
 Fortunately true cases of retained infantile
swallow are rare.

48. Conclusion
 Though a lot of misinformation regarding
deglutition(swallowing) is present in many
literatures as it is of interest in many fields
like dentistry, oral physiology, speech,
otolaryngology, etc but as a orthodontist we
are concerned only with various
malocclusions, abnormal mastication and
feeding habits that are related to abnormal
swallowing patterns which may or may not
be abnormal in other fields.

49. References
 Handbook of Orthodontics (Moyers)
 Contemporary orthodontics(Profitt)
 Textbook of Medical Physiology (Guyton)

50. ThankYou