Mastication And Deglutition

1. PRESENTED BY-
DR. AISHWARYA ARYA
DR. ENU KAMBOJ
DR. KRITTIKA KUHAR
FIRST YEAR MDS
MASTICATION AND
DEGLUTITION

2. CONTENTS
INTRODUCTION
FACTS ABOUT MASTICATION
TYPES OF MUSCLES
IMPORTANCE OF MUSCLES
OF MASTICATION
CHEWING RELEX
CLASSIFICATION
MASTICATORY MUSCLE
DISORDERS
DEGLUTITION
APPLIED ASPECTS

3. MASTICATION
GPT 8-
• MASTICATION Is defined as a process of chewing food in preparation for
swallowing and digestion.
• The teeth are admirably designed for chewing, the anterior teeth (incisors and
canines) providing a strong cutting action and the posterior teeth ( pre molars
and molars), providing a grinding action during mastication.
• The biting stresses that are exerted during mastication is difficult to analyse
because of the dynamic nature of different tooth structures
• Highest biting force- 4337 N
• Maximum bite force ranges from
400 to 890 N for molars
222-445 N for premolars
133-334 N for canines
89- 111N for incisors
Phillip’s Science Of Dental Materials- Anusavice Shen Rawls- 12th Edition

4. FACTS ABOUT MASTICATION
• The effects of muscle thickness on bone morphology can be explained by Wolff’s
law- states that the internal structure and the shape of the bone are closely
related to the bone’s function.
• Individuals with skeletal class I jaw relationship had thicker muscles of
mastication when compared to the skeletal class II subjects.
• Dental arches are the somatic sites where excessive psychoemotional tension can
be diffused and reduced. This is manifested by clenching or grinding the teeth
bruxism.
Reference -Masseter muscle thickness in different skeletal morphology: An ultrasonographic study Sushma Rani,
MS Ravi- ABShetty College of Dental Sciences

5. Mastication or chewing is the first mechanical process
to which food is subjected. This process helps in
• Breakdown of food stuff into smaller particles
• Mixing of saliva with food substances thoroughly
• Lubrication and moistening of dry food by saliva so
that the bolus formed can be easily swallowed
• Appreciation of taste of the food by the presence of
taste buds on tongue.
SIGNIFICANCE OF MASTICATION

6. PHYSIOLOGY
• The first movement in the digestive tract ( oral
cavity) which by nature is voluntary as well as an
act of learned reflex.
• Large pieces of food are broken apart and surface
area increased for the efficient action of digestive
enzymes and reduced for swallowing.
ROLE OF TONGUE :
It plays essential role in controlling the movement of
food and forming the bolus.

7. MASTICATORY SEQUENCE
• It consists of a number of masticatory cycles and
extends from INGESTION to SWALLOWING.
It is divided into 3 consecutive cycles-
A- PREPARATORY PERIOD-this is the initial period in
which food is transported back to posterior teeth.
B- REDUCTION PERIOD – In this period , food is
grounded to pieces.
C – PRE SWALLOWING – This is the final period in
which bolus is formed.

8. Presence of a bolus of food in the mouth at first initiates
reflex inhibition of the muscles of mastication, which
allows the lower jaw to drop.
The drop in turn initiates a stretch reflex of the jaw
muscles that leads to rebound contraction.
CHEWING REFLEX
 This automatically raises the jaw to cause closure
of the teeth, but it also compress the bolus
against the linings of the mouth, which inhibits
the jaw muscles once again, allowing the jaw to
drop and rebound another time; this is repeated
again and again.

9. • Depression of jaw
• Elevation of jaw
• Protraction of jaw
• Retraction of jaw
MOVEMENTS OF JAW

10. PRIMARY MUSCLES OF
MASTICATION

11.  It is one of the most important muscle of mastication.
It is the superficial, quadrilateral muscle covering the lateral surface of ramus
of mandible
• A- Superficial part
• B– Middle part
• C- Deep part
MASSETER MUSCLE
NERVE SUPPLY – Massetric
nerve ,branch of anterior
division of mandibular nerve
BLOOD SUPPLY- Massetric artery ,
branch of maxillary artery.

12. TEMPORALIS MUSCLE
Fan shaped muscle covering the region of temporal
fossa.
It is broad , present on each side of head – superior to
zygomatic arch.
BLOOD SUPPLY- It is
supplied by superficial
and deep temporal artery
and a network of deep
plexus of veins
NERVE SUPPLY- Two
deep temporal branch
from the anterior
division of mandibular
nerve

13. LATERAL PTERYGOID MUSCLE
Consists of short conical muscle , fan-shaped muscle
located in the infratemporal fossa of the skull.
Made up of two heads-
 A- Upper head
 B- Lower head
NERVE SUPPLY
BLOOD SUPPLY
A branch of anterior
division of
mandibular nerve
Pterygoid artery ,
branch of second part
of maxillary artery

14. MEDIAL PTERYGOID MUSCLE
Also called as the internal pterygoid muscle
It is almost mirror image like masseter muscle
Rhomboidal in shape and in same direction on the inner surface of mandible
SUPERFICIAL
HEAD
DEEEP HEAD
ORIGIN From the
tuberosity of
maxilla and
adjoining bone
Medial surface
of lateral
pterygoid
plate and
adjoining
process of
palantine bone
INSERTION- superficial and deep
insert into the roughened area of
medial surface of angle and
adjoining ramus of mandible ,
below and behind the
mandibular foramen and
mylohyoid groove

15. DEGLUTITION
Deglutition or swallowing is the
process by which food is passed from
mouth into stomach.
Stages of Deglutition:-
I. Oral stage when food enters
pharynx from mouth.
II. Pharyngeal stage when food
enters esophagus from pharynx.
III. Esophageal stage when food
enters stomach from esophagus .

16. Oral Stage Or First Stage
In this stage the bolus passes through the
oral cavity into the pharynx by means of
series of actions such as:
1.The bolus is placed over posterodorsal
surface of the tongue. It is called the
preparatory position.
2.The anterior part of the tongue is retracted
and depressed.
3.The posterior part of the tongue is elevated
and retracted against the hard palate. This
pushes the bolus backwards into the
pharynx.
4.The forceful contraction of tongue against
the hard palate produces a positive
pressure in the posterior part of the oral
cavity. This pressure also pushes the food
into the pharynx.

18. Pharyngeal Stage Or Second Stage
This stage shows involuntary, complex, closely
coordinated movements in the pharynx the
pushes the bolus into the esophagus. It lasts
for 1-2 seconds
Features
1.Soft palate is elevated and thrown against
posterior pharyngeal wall to close off the
nasal cavity. This prevents the food from
entering the nasal cavity.
2.Larynx rises with elevation of hyoid bone,
vocal cords are approximated and breathing is
momentarily inhibited(deglutition
apnoea).Epiglottis guards the laryngeal
opening until bolus reaches the esophagus.

19. 3.Posterior pillars of fauces i.e.
palatopharyngeal folds
approximate to shut off the
mouth cavity.
4.Cricopharyngeous muscle
briefly relaxes and bolus enters
the upper esophagus.
5.Then cricopharyngeal muscle
contracts and vocal cords open
to allow resumption of rhythmic
breathing

20. Esophageal Stage or Third
Stage
• In esophageal stage food enters
stomach from esophagus.
• It is an involuntary stage.
• The function of esophagus is to
transport the bolus from the pharynx to
the stomach. The movements of
esophagus are specially organized for
this function and the movements are
called peristaltic waves.

21. Role of Lower Esophageal Sphincter
• The distal 2-5cm of esophagus acts like a sphincter
and it is called lower esophageal spincter.
• Its is always constricted.
• It only relaxes when the food enters this part of
the esophagus and constrictes as the food enters
the stomach.

22. Deglutition reflex

23. APPLIED ASPECTS

24. Dysphagia
• Difficulty of swallowing
–co exits with heartburn
and vomiting .
• Deglutition can be
restricted if the muscle
of the mouth , pharynx,
larynx or esophagus are
weak or uncordinated.

25. ACHALASIA CARDIA
• It is a disease of an
unknown etiology
characterized by
aperistalsis in the body
of oesophagus and
failure of relaxation of
lower oesophageal
sphincter on initiation of
swallowing .
• The food collects in
oesophagus resulting in
dilatation of
oesophagus

26. GASTROESOPHAGEAL REFLUX DISEASE
• It is characterised by regurgitation of acidic gastric
content through esophagus. The gastric content
flows into pharynx/mouth. Regurgitation is due to
weakness/incompetence of lower esophageal
sphincter.

27. FEATURES OF GERD
• Heartburn or pyrosis-
painful or burning sensation
in chest due to
regurgitation of acidic
gastric content.
• Esophagitis
• Dysphagia
• Cough and change of voice
• Esophageal ulcers and
cancer (in chronic cases)

28. GAG REFLEX
DENTAL IMPLICATION- Most of our patients in our day to day practice presents with
gag reflex during making of impressions or carrying out restorative procedures.

29. PRESBYPHAGIA

30. CHOKING
DENTAL IMPLICATIONS-
Sudden aspiration of
instruments or materials
used in dentistry can result
I chocking effects.

31. DEGLUTITION APNEA
• Arrest of breathing during deglutition
• Occurs reflexly during pharyngeal stage.
• When bolus is pushed into oesophagus from
pharynx during pharyngeal stage , there is
possibility for the bolus to enter the respiratory
passage through trachea .

32. PHAGOPHOBIA –
Fear of swallowing as in rabies , tetanus, pharyngeal
paralysis due to fear of aspiration .
GLOBUS HYSTERICUS –
Sensation of lump lodges in throat .
ODYNOPHAGIA –
Painful swallowing .

33. Investigation
• X-ray chest
• Barium swallow
• Oesophagoscopy

34. ESSENTIALS OF MEDICAL PHYSIOLOGY – 5TH EDITION
K SEMBULINGAM
PREM SEMBULINGAM
TEXTBOOK OF PHYSIOLOGY – PROF. AK JAIN
 Philips- Science Of Dental Materials- Anusavice Shen Rawls- 12th
Edition
REFERENCES
Masseter muscle thickness in different skeletal morphology: An ultrasonographic
study Sushma Rani, MS Ravi- Ab Shetty college of dental sciences
ARTICLES-