Anatomy and Physiology of Oral Cavity & Oropharynx

1. Anatomy and
Physiology of
Oral Cavity &
Oropharynx
Dr. S. Prem Davis
Department of ENT
SVMCH & RC
Puducherry

2. Oral Cavity in ENT’s perspective

3. Outline
 Oral Cavity
1. Lips
2. Hard Palate
3. Anterior Tongue
4. Buccal Mucosa
5. Retromolar Trigone
6. Floor of Mouth
 Oropharynx
1. Palantine Tonsils
2. Tongue Base
3. Lateral and Posterior
Pharyngeal wall
4. Soft Palate

4. Oral Cavity
 Oral Cavity extends from Lips &
cheeks to anterior Pillars
(Palatoglossal Arch)
 Has roof, floor and lateral walls
 Opens onto the face via Oral
Fissure
 Continuing with the cavity of
oropharynx at Oropharyngeal
Isthmus

5. Oropharyngeal Isthmus
 Laterally – Palatoglossal Arch
 Superiorly – Soft Palate
 Inferiorly – Sulcus Terminalis
 Closure by Oropharyngeal
Isthmus?

6. Subsites – Oral Cavity
1. Lips
2. Hard Palate
3. Anterior Tongue
4. Buccal Mucosa
5. Retromolar Trigone
6. Floor of Mouth

7. Development of Oral Cavity
 4th Week of IUL
 Partly form Stomodeum and
foregut
 Mesodermal thickening
appears in the cranial most
part of the foregut.
 1st and 2nd arch – Mouth and
Oral cavity

9. 5th Week
 Nasal placode is
surrounded by a by Lateral
and Medial Nasal
Processes with nasal pit in
the middle.
 The nasal pits deepen and
rupture, forming
communications between
the nasal and oral cavities,
called Primary Choanae.

10. 7th Week
 Maxillary processes fuses with the Medial nasal swellings.
 Primary Palate
 Complete by the end of the seventh week
 Fusion of the paired maxillary prominences with the paired medial
nasal prominences forms the Complete Upper Lip
 (maxillary prominences form lateral lip)
 The lateral nasal prominences form the Bilateral Nasal Ala

12. Subsite 1: Lips
 2 Parts – Upper and Lower part
 Begins at the junction of the
Vermilion border of the Skin
 Forms the Anterior aspect of the Oral
Vestibule
 Oral Fissure – Slit like opening
between Lips – Connects the oral
vestibule to outside

13. Lips
 Covered externally by skin and
internally by the labial mucosa
 Encloses – Orbicularis Oris
muscle, Neurovascular
structures, labial glands and soft
tissue

14. Other Muscles
 Neighboring muscles of facial
expression – Angle of mouth
 Upper Lip – Buccinator, Depressor
Anguli Oris
 Lower Lip – Buccinator, Levator Anguli
Oris, Zygomaticus major
 Incisive Labii Superioris & Inferioris –
Accessory Muscles - Modiolus

15. Arterial Supply & Vermilion Border
 Superior and Inferior Labial
Artery (Facial Artery)
 Nerve Supply - VII
 Vermilion Border Characteristic
of Human
 Blood vessels are closer to the
surface in areas where the skin
is thin – Vermilion Border

16. Philtrum
 Upper lip has a shallow ridge on
its external surface sandwiched
between two elevated ridges of
the skin
 Formed embryologically by
fusion of the Medial Nasal
Process

17. Lips Pits
 AD, U/L OR B/L Blind Tracts
 Hirschsprung's disease and type-1 orofaciodigital syndrome.

18.  Para Median Cleft Lip
 Van den Woude Syndrome
 AD
 Lower Lip Pits, Cleft Lip, Cleft Palate

19. Popliteal
Pterygium
Syndrome
 AD
 Cleft lip, cleft palate
 Webbing of toes and
fingers
 Lip pits
 Extensive web running
from behind the knee
down to the heel

20. Thin Upper Lips

21. Double Lip
 Usually Congenital
 Upper Lip > Lower Lip
 Double lip is caused by excessive
areolar tissue and non-
inflammatory labial mucous gland
hyperplasia
 Conditions:
 Ascher Syndrome: Double upper
lip, blepharochalasis, and nontoxic
enlargement of the thyroid gland.

22. Median Labial Frenulum
 Fold of mucosa connects
the inner lips to adjacent
gums
 Restricts the mobility

23. Oral Cavity - Divisions
 Separated into two
regions by Upper and
Lower dental arches
consist of teeth and
alveolar bones as
1. Oral Vestibule
2. Oral cavity Proper

24. Oral Vestibule
 Horseshoe shaped
 Between dental arches and
deep surface of the cheeks
and lips
 Oral fissures opens into it

25. Oral Cavity Proper
 Extension - Inner surface of
Teeth to Anterior Tonsillar Pillars
or Oropharyngeal Isthmus
 Roof – Palate
 Floor – Mylohyoid muscles
 Lateral wall – Cheeks and
Retromolar regions

26. Palate Bone
 Two Regions
1. Hard Palate
2. Soft Palate

28. Subsite 2: Hard Palate

29.  Formed by
Palantine Processes of Maxilla –
Anterior 2/3
Horizontal Plates of the Palantine
bone –Posterior 1/3
Partition between Nasal & Oral
Cavities
Margins
Anterolateral – Alveolar Gums &
Posterior – Soft Palate
Superior – Floor of Nasal Cavity
Inferior – Roof of Oral Cavity

30.  Oral mucosa is bounded tightly
to underlying Periosteum.
 Periphery of the hard palate
surrounding necks of teeth –
Gingiva
 Palantine Raphe – Runs
anteroposteriorly lacks
submucosa

31. Incisive Papilla & Foramen

32. Incisive Foramen & Lining Epithelium
 a/k/s nasopalatine Canal; foramina of Stensen.
 Nasopalatine nerve and the vascular anastomosis between the Greater
Palatine and Sphenopalatine arteries.
Lining Epithelium
Upper Nasal Surface – Ciliated respiratory epithelium
Lower Oral Surface – Keratinized Epithelium

33. Palantine Ridges / Rugae
 Hard palate has irregular
transverse ridges
 Pattern of rugae is unique is
unique for individual
 Helps in identifying dead
individual – Forensic Science.

34. Greater Palantine Foramen
 Formed by horizontal plate of
palantine bone and laterally by
adjacent part of maxilla
 Is the inferior opening of the
Palantine canal
 Continues superiorly as
pterygopalatine fossa
 Transmits Greater Palantine
Nerve and vessels to palate.

35. Lesser Palantine Foramen
 Submucosa in the posterior half of
the soft palate contains numerous
salivary glands.
 Larger collecting ducts which
collects secretions from these
smaller salivary glands opens at the
Palantine Fovea.
Minor Salivary Glands
 Is the inferior opening of the
palatine canal
 Transmits Lesser Palantine Nerve
and vessels to the Soft Palate

36. Posterior Nasal Spine
 Single
 Formed at the midline where two
horizontal plates of Palantine bone
meets
 Projects Backwards
 The posterior margin of horizontal
plate and posterior nasal spine are
associated with the attachment of
the soft palate.

37. Cleft Palate

38. Soft Palate
 Mobile flap suspended from the back of the hard palate.
 Acts as a valve by
1. Depressed to close the oropharyngeal isthmus
2. Elevated to separate the nasopharynx from oropharynx
 Differentiated from hard palate by change in colour.
 Soft palate is darker red with yellowish tint.

39. Contents of Soft Palate
 Soft palate contains an aponeurosis, muscular tissues, vessels
nerves, lymphoid tissue and mucous glands.
Muscles of soft palate
 Tensor Veli Palatini
 Levator Veli Palatini
 Palatopharyngeus
 Palatoglossus
 Musculus Uvulae
 All muscles supplied by Vagus except Tensor Veli Palatini by
V3.

40. Tensor Veli Palatini
 Origin – Scaphoid fossa of sphenoid
bone & Fibrous part of Pharyngo
tympanic Tube, Spine of Sphenoid
 Insertion – Palantine Aponeurosis
 Innervation - Mandibular Nerve via the
branch to medial pterygoid muscle
 Function – Tenses the soft palate and
opens the Pharyngotympanic Tube

41. Levator Veli Palatini
 Origin – Petrous part of temporal bone
anterior to opening for carotid canal
 Insertion – Superior surface of the
Palantine Aponeurosis
 Innervation – Vagus nerve via pharyngeal
branch to pharyngeal plexus
 Function – only muscle to elevate the soft
palate above the neutral position.

42. Palatopharyngeus
 Origin –superior surface of Palantine
aponeurosis
 Insertion – Pharyngeal wall
 Innervation - Vagus nerve via
pharyngeal branch to pharyngeal
plexus
 Function – Depresses Palate Moves
Palatoglossal arch towards midline,
Elevates Pharynx

43. Palatoglossus
 Origin –Inferior Surface of Palantine
Aponeurosis
 Insertion – Lateral margin of
tongue
 Innervation - Vagus nerve via
pharyngeal branch to pharyngeal
plexus
 Function – Depresses Palate
Moves Palatoglossal arch towards
midline

44. Palatoglossal and Palatopharyngeus
Arches

45. Musculus Uvulae
 Origin – Posterior Nasal Spine of Hard
palate
 Insertion – Connective tissue of uvula
 Innervation - Vagus nerve via pharyngeal
branch to pharyngeal plexus
 Function – Elevates and retracts uvula;
thickens the central region of soft palate.

46. Bifid Uvula
 Associated with Cleft Palate
 Seen in 2 % of normal population
 Recurrent Middle ear Infection
 Loeys–Dietz syndrome ?? Add??

47. Arterial Supply
 Greater Palantine branch of
Maxillary Artery
 Lesser Palantine Artery
 Ascending palantine branch
of facial artery
 Palantine branch of
pharyngeal artery

48. Venous and Lymphatic Drainage
 Veins follow arteries usually
follow pterygoid plexus of
veins in the infratemporal
fossa (or)
 Into a network of veins
associated with palantine
tonsils which drains in
pharyngeal plexus of veins or
directly into facial vein.

49. Nerve Supply
 Greater Palantine & Lesser Palantine Nerve
 Nasopalatine Nerve

50. Cheeks
 Walls of the oral cavity formed by cheeks
 Each cheek consists of facia and layer of skeletal muscle
sandwiched between skin eternally and oral mucosa internally.
 The thin layer of skeletal muscle within cheek is buccinator
muscle.

51. Buccinator Muscle
 Origin – Posterior margin joined
with the anterior margin of superior
constrictor muscle by
pterygomandibular raphe
 Alveolar part of the maxilla and
mandible.
 Insertion – blends with orbicularis
Oris and insert into modiolus
 Innervation – Buccal branch of facial
nerve
 General sensation of skin and oral
mucosa – Buccal branch of
mandibular nerve.

52. Buccinator Muscle
 Function – Hold the cheeks against alveolar arches and
keeps the food between teeth while chewing
 Arterial Supply – Buccal branch of Facial and Maxillary artery

53. Cheek Dimple
 Muscle causing Cheek Dimple?
 ? Buccinator
 Never
 It is Zygomaticus Major Muscle
 Zygomatic Bone to Corner of
Mouth

54. Subsite 3: Buccal Mucosa
 Mucosal surface of cheeks and lips
 Continuous with the vermilion of the lip to the pharyngeal
mucosa at the oropharyngeal isthmus.
Types
 Masticatory mucosa
 Lining mucosa
 Specialised mucosa

55. Masticatory Mucosa
 Covers the gingiva and hard palate
 Keratinised epithelium and has dense fibrous lamina propria
 Pink in colour
 Submucosa is absent in gingiva and midline palatine raphe
 Masticatory mucosa is bound firmly to underlying bone or to the
neck of the teeth forming in the gingivae and palantine raphe a
mucoperiosteum.

56. Lining Mucosa
 Covers the internal surfaces of the lips, cheeks, floor of the
mouth, soft palate, ventral surface of tongue and alveolar
processes.
 Amounting for 60% of the total area
 Red in colour
 Non keratinised stratified squamous epithelium
 Lining Mucosa – Loosely attached – alveolar Mucosa,
vestibular fornix and Floor of mouth
 Firmly attached – Lips, cheeks, soft palate, ventral surface of
tongue

57. Specialised Mucosa
 Gustatory mucosa covers the anterior 2/3rd of dorsum of tongue.
 Vermilion of the lip separates the skin from lining mucosa –
shares features of lining and masticatory mucosa
 The junctional epithelium attaches the tooth to the gingiva has
distinguished features from other stratified squamous epithelia
(e.g. internal and external basal lamina)

58. Subsite 3: Retromolar Trigone
 Triangular area of mucosa
covering the anterior surface
of the ascending ramus of the
mandible.
 Base – Posterior to the Last
Molar
 Apex – Adjacent to the
tuberosity of the maxilla.

59. Importance of Retromolar Trigone
 Mucosa is closely adherent to the ascending ramus of the
mandible
 Carcinoma in this region often invades the mandible.
 Referred otalgia results from innervation by V3, lesser
palantine nerve and glossopharyngeal nerve.
 Lymphatics to Level II node.

60. Development of Tongue
 Medial most part of mandibular arch
– lingual swelling
 Separated in midline by tuberculum
impair
 Anterior 2/3rd tongue – fusion of
Lingual swelling and tuberculum
impair
 Posterior 1/3rd tongue – cranial part
of Hypobranchial eminence (Copula)

61. Subsite 4: Anterior 2/3rd Tongue
 Highly muscular organ for deglutination, taste and
speech.
 Doral & Ventral Surface, Root & apex
 Anterior 2/3rd and posterior 1/3rd separated by
sulcus terminalis.
 Root – attached to mandible and hyoid
 Anterior 2/3rd tongue is oriented in horizontal plane.
 Sulcus terminalis forms the inferior margin of
oropharyngeal isthmus.

62. Papillae
 Filiform Papillae – small cone like
projections that end in one or more
points. No taste buds.
 Fungiform papillae – round, larger
than filiform. concentrated along
the margins of the tongue.
 Vallate Papillae – cylindrical. 8 to 12
in no. anterior to sulcus terminalis.
 Foliate papillae – linear fold of
mucosa on side of tongue near
terminal sulcus.

63. Inferior surface of tongue
 Undersurface lacks papillae
 Linear folds
 Median fold – frenulum of tongue –
continuous with the mucosa of the oral
cavity
 Separates into right and left sides of
tongue
 Lingual vein present on both sides of
frenulum
 Fimbriated fold present lateral to vein.

64. Muscles
 4 Extrinsic muscles and 4 Intrinsic Muscles
Extrinsic Muscles
 Genioglossus
 Hyoglossus
 Styloglossus
 Palatoglossus
 Functions: Protrude, retract, depress and elevate the tongue

65. Genioglossus- Fan shaped Muscle
 Origin –Superior Mental Spine
 Insertion – Body of Hyoid
 Innervation- XII (Hypoglossal Nerve)
 Function – Protrudes tongue

66. Hyoglossus
 Origin – Greater Horn
and adjacent part of
body of hyoid
 Insertion – lateral surface
of tongue
 Innervation – XII
 Function – Depresses
tongue

67. Styloglossus
 Origin- Styloid Process
(Anterolateral surface)
 Insertion – Lateral surface of
tongue
 Innervation – Hypoglossal
Nerve
 Function – Elevates and
retracts tongue

68. Palatoglossus
 Origin – Inferior surface of Palantine
Aponeurosis
 Insertion – Lateral margin of tongue
 Innervation – Hypoglossal Nerve
 Function – Depresses Palate, Moves
palatoglossal fold toward midline and
elevates back tongue.

69. Intrinsic Muscles of Tongue
 Originates and insets within the substance of the tongue
 4 in number
 1. Superior Longitudinal
 2. Inferior Longitudinal
 3. Transverse
 4. Vertical
 Innervation – XII Nerve
 Function – 1. Lengthening, Shortening
 2. Curling and uncurling – apex, Flattening & rounding its surface

71. Arterial Supply and Venous Supply
 Arterial Supply –
 Lingual Artery – External Carotid Artery
 Venous Drainage
 Dorsal Lingual Vein
 Deep Lingual Vein
 Lymphatics
 Pharyngeal Part – Jugulodigastric LN
 Oral Part – directly – Deep Cervical
 Indirectly – by passing mylohyoid
muscles into submental and
Submandibular

72. Nerve Supply

73. Microglossia
 Seen in
 Oromandibular Limb Hypo genesis
Syndrome
 Cleft Palate
 Dental Agenesis
 Hypoplasia of Mandible

74. Macroglossia
 Acromegaly
 Primary Amyloidosis
 Congenital Hypothyroidism
 Down Syndrome
 Beckwith- Wiedemann
Syndrome
 Maligancies

75. Bifid Tongue
(Glossoschissis)
 Failure of the lateral lingual swellings
to merge
 Seen in
 Oral-facial-digital syndrome
 Ellis–van Creveld syndrome
 Klippel–Feil anomaly
 Larsen syndrome
 Goldenhar Syndrome

76. Ankyloglossia
 Failure of the Lingual Frenulum
to separate from Floor of the
Mouth
 Speech impairments
 Swallowing difficulties
 Difficulty moving the tongue
toward the roof

77. Subsite 5: Floor of the Mouth
 Formed by
 1. Muscular Diaphragm – Paired Mylohyoid Muscle
 2. Above Diaphragm – two cord like Geniohyoid Muscle
 3. Tongue – Superior to Geniohyoid Muscle
 Glands – Sublingual and Submandibular Gland

78. Mylohyoid Muscle
 Origin – Mylohyoid line of
mandible
 Insertion – Median fibrous raphe
and adjacent part of hyoid bone
 Innervation – Nerve to
Mylohyoid – inferior alveolar
branch of mandibular nerve

79. Geniohyoid Muscle
 Origin – Inferior mental spines of
mandible
 Insertion – Body of hyoid bone
 Innervation – C1
 Functions – Supports and
elevates the floor of the oral
cavity. Depress the mandible
when hyoid is fixed.

80. Gateway into the Floor of Oral Cavity
 Major route by which structures
in the upper neck and
infratemporal fossa of head
passes to and from structures in
the floor of the oral cavity.
 Structures passes through
 Hyoglossus styloglossus
 Lingual artery and vein
 Lingual Nerve, XII Nerve, IX
nerve and lymphatics.

81. Oropharynx
 Extent
 Oropharyngeal isthmus
 Soft palate
 Upper margin of epiglottis
 Relation
 Anterior – Oral cavity
 Superior – Nasopharynx
 Posterior Inferior –
Hypopharynx

82. Oropharynx - Subsites
 1. Palantine Tonsils
 2. Tongue Base
 3. Lateral and Posterior Pharyngeal wall

83. Subsite 1: Palantine Tonsils
 Mass of lymphoid tissue situated in the
lateral wall of oropharynx
 Between palatoglossal and
Palatopharyngeus arches
 Anterior inferior portion of Waldeyer’s ring
 Waldeyer’s Ring
 Pharyngeal Tonsil
 Tubal Tonsil
 Palantine Tonsil
 Lingual Tonsil
 Lateral Pharyngeal bands-
 Discrete Nodules

84.  A tonsil presents two surfaces
 two poles
 Medial surface of the tonsil is covered by nonkeratinizing stratified
squamous epithelium which dips into the substance of tonsil in the form
of crypts.
 Openings of 12–15 crypts can be seen on the medial surface of the tonsil.
 One of the crypts, situated near the upper part of tonsil is very large and
deep and is called crypta magna or intratonsillar cleft
 the main crypts arise the secondary crypts, within the substance of tonsil.

85.  Lateral surface has fibrous capsule. Between the capsule and the
bed of tonsil is the loose areolar tissue.
 Upper pole of the tonsil extends into soft palate. Its medial surface
is covered by a semilunar fold, extending between anterior and
posterior pillars and enclosing a potential space called
supratonsillar fossa.
 Lower pole of the tonsil is attached to the tongue. A triangular fold
of mucous membrane extends from anterior pillar to the
anteroinferior part of tonsil and encloses a space called anterior
tonsillar space.
 The tonsil is separated from the tongue by a sulcus called
tonsillolingual sulcus which may be the seat of carcinoma.

86. Bed of the Tonsil

87. Arterial Supply

88. Venous and Lymphatic Drainage
 Para Tonsillar Vein – common facial vein and pharyngeal venous
plexus
 Lymphatics
 Upper Deep Cervical Lymph Node
 Jugulo Digastric Lymph Node
 Nerve Supply
 Lesser Palantine Branch of Sphenopalatine ganglion
 Glossopharyngeal Nerve

89. Subsite 2: Tongue Base (Posterior 1/3rd)
 Posterior 1/3rd of the tongue
 Lying behind the sulcus
terminalis
 Forms the anterior wall of
oropharynx
 Its mucosa reflected on to the
epiglottis as medical and
lateral glossoepiglottic fold.
 Glossoepiglottic fold
surrounds vallecula

90. Lingual Tonsils
 Pharyngeal part of tongue has underlying lymphoid nodules
– Lingual Tonsils
 Part of Waldeyer’ s ring.

91. Pharyngeal Wall
 Formed by Mucous Membrane, skeletal muscles and fascia
 Pharyngeal muscles
 Constrictors
Superior Constrictor
Middle Constrictor
Inferior Constrictor
 Longitudinal Muscles
Stylopharyngeus
Salpingopharyngeus
Palatopharyngeus

92. Mucous Membrane
 Continuous with the Eustachian tube, Oral cavity, larynx
 Nasopharynx lined by pseudostratified columnar ciliated
epithelium upto soft palate
 Oro and hypopharynx lined by non keratinised stratified
squamous epithelium.
 Transitional zone present

93. Pharyngobasilar Fascia
 Fibrous sheet between mucous membrane and pharyngeal
muscle layer.
 Thicker above & attached superiorly to basilar region of occipital
bone
 Posteriorly it is strengthened by strong band (median raphe) which
gives attachment to constrictors.

94. Constrictor Muscles
 Major contributor for the Pharyngeal
Wall
 Posteriorly joined together by
Pharyngeal Raphe
 Arrangements – Flower pot stacked
one on other.
 Action –
Constricts and narrow the
pharyngeal cavity.
Sequential contractions helps in
propulsion of food bolus.

95. Constrictor’s
 Posterior Attachment –
Pharyngeal raphe
Muscles Posterior
Attachment
Anterior
Attachment
Innerva
tion
Action
Superior
Constrictor
Pharyngeal
raphe
Pterygomandibular
raphe and adjacent
bone on the mandible
and pterygoid
X
ConstrictionofPharynx
Middle
Constrictor
Upper margin of
greater horn of hyoid
bone and adjacent
margins of lesser horn
and stylohyoid
ligament

96. Longitudinal Muscles
Muscle Origin Insertion Innervation Function
Stylo
Medial side of
base of styloid
process
PharyngealWall
IX
Elevation of
Pharynx
Salpino
pharyngeus
Inferior aspect of
pharyngeal
X
Elevation of
Pharynx
Palato
pharyngeus
Upper surface of
palantine
aponeurosis
Elevation of
Pharynx &
closure of
Oropharynge
isthmus

97. Structures Passing between Muscles
 Between Superior and Middle Constrictor – IX Nerve,
Stylopharyngeus muscle
 Between Middle and Inferior Constrictor – Internal branch of
Superior Laryngeal Nerve
 Between Inferior constrictor and oesophagus – Recurrent
Laryngeal Nerve, inferior laryngeal artery

98. Forman of Morgagni
 Between Base of skull and upper border of Superior
Constrictor
 Structures Passed
Tensor Palati
Ascending Palantine Artery
Ascending Pharyngeal Artery
Levator Palati
Auditory Tube

99. Buccopharyngeal Fascia
 Covers the outer surface of constrictor
 Extend forward over the pterygomandibular
ligament on the buccinator muscle
 Posteriorly =, it is loosely attached to the prevertebral
fascia.
 Laterally, it is attached to the styloid process, its
muscle and to the carotid sheath.
 Superiorly, above the upper border of the superior
constrictor it is firmly united with the Pharyngobasilar
fascia.

100. Blood supply of Pharynx
 Ascending Pharyngeal artery
 Ascending palantine and tonsillar branch of facial artery
 Branch of internal maxillary artery chiefly the ascending palantine
 Dorsalis linguae branch of lingual artery
 Venous Supply
 Common facial vein into internal jugular vein

101. Nerve Supply
 Pharyngeal plexus of nerves
 Formed by
Pharyngeal branch of Vagus
Pharyngeal branch of glossopharyngeal
Pharyngeal branches of superior cervical sympathetic ganglion.

102. Motor Fibre
 All muscles are supplied by Vagus except stylopharyngeus
supplied by IX Nerve
Sensory Fibre
 Branches from Glossopharyngeal and Vagus nerve.
 Nasopharynx – Pharyngeal branches of maxillary nerve through
pterygopalatine ganglion.
 Soft palate & tonsil – Lesser Palantine & IX Nerve.

103. Taste Sensation
 From the Vallecula and Epiglottic area – pass through internal
laryngeal branch of Vagus.
Lymphatic Drainage of Pharynx
 Deep Cervical Lymph Nodes.

104. Physiology of Oral cavity & Oropharynx
 Swallowing
 Definition
 Innervation of major
muscles
 Phases
 Neural mechanism
 Applied Aspects
MASTICATION & DEGLUTITION
 Mastication
 Definition
 Masticatory
movements
 Role of tongue
 Action of muscles
 Neural mechanism
 Applied Aspects

105. Mastication
 Mastication of food is the initial stage in the process of digestion.
Large pieces of food are reduced for swallowing
 Mastication is initiated reflexly following the presence of food in
the mouth
 Functions:
Cuts & grinds larger food particles into smaller one
Increases salivary secretion
Mixes food with saliva
Lubricates the content of oral cavity to make swallowing easier
Breaks starch and allows saliva to mix with starch.

106. Chewing
 Four Group of muscles
Muscle Action
Masseter Elevates Mandible & helps in clenching of teeth
Temporalis Helps in retracting mandible
Pterygoids
Protrude mandible and depress chin. Helps in
opening of mouth & alternative contraction of
right and left helps in grinding movements
Buccinator
Prevents accumulation of food between cheek
and mandible

107. Masticatory Movements
 The jaw moves rhythmically, opening and closing in a series of cyclical
movements.
 4 Phases

108. Masticatory Phases
Slowopening
Tongue moves
forward and
expand beneath
the food
Fastopening&fastclosing
The hyoid
bone and the
tongue
retract, forms a
trough.
Moves the food
to post oral
cavity
Food is moved
backward below
soft palate by
squeezing effect
of tongue.

109.  Chain Reflex Theory of Mastication
 In 1917, C.S. Sherrington
 Biting on a piece of food initiated the jaw-opening reflex; the resulting
opening stretched the closer muscles and initiated the jaw- closing
response. The alternation of these processes then maintained the rhythmic
pattern, and produced the movements of mastication.

110.  With the development of electromyographic and neuronal
recording techniques, the theory was found to make some false
predictions:
 1. Paralysis of the muscles should eliminate the masticatory pattern.
 Dellow and Lund (1971) showed that the rhythmic activity of
masseter, mylohyoid and hypoglossal nerves persisted after paralysis
with gallamine.

111. Control of Mastication
 Cyclical movements
generated and controlled at
the level of brainstem.
 Complex interactions between
several motor nuclei and sensory
input from oral cavity, terminating
primarily in the trigeminal sensory
and mesencephalic nuclei.

112. Swallowing or Deglutition
 Swallowing is the process by which the food from oral cavity is
transported into esophagus.
 Though it is initiated voluntarily, most part of it is involuntary or
reflexive called deglutition reflex.
 Reflex sequence of muscle contractions that propels ingested
materials and pooled saliva from mouth to the stomach.
 Swallowing occurs as many as 1000 times in 24 hours.
 Swallowing frequency is highest during eating, least during sleep and
occurs at a rate of about once per minute at other times.

113. Stages of Deglutition
 The process of swallowing can be divided into four stages :
1. Preparatory Stage- Merges into terminal phase of mastication
2. Oral Stage- 0.5 s
3. Pharyngeal Stage- 0.7 s
4. Esophageal Stage- Liquids 3 s, Solid 9 s

114. Oral Phase
 a/k/s buccal phase
 Voluntary phase of swallowing
 Initiated when the tongue separates a bolus of food from mass of
foodstuff present in the mouth.
 At beginning- tip of tongue presses against hard palate followed
by body of tongue presses it
 This action brings the food into oral cavity and then into pharynx
 Once the food touches receptors at pharyngeal opening,
swallowing reflex is initiated.

115. Pharyngeal Phase
 Afferent – Impulses from pharyngeal receptors are transmitted
through trigeminal, glossopharyngeal and Vagus nerves
 Centre – Nucleus Tractus Solitarius and Nucleus Ambiguous in
medulla
 Efferent – Muscles of Pharynx and tongue innervated by
trigeminal, glossopharyngeal, Vagus and hypoglossal nerves.

116. Pharyngeal Phase Events
 The soft palate is pulled in upward direction. The
palatopharyngeal folds move in inward direction. Prevents the
entry of food into nasopharynx.
 Closure of laryngeal opening by vocal cord closure and forward
and upward movement of larynx against epiglottis
 Constriction of the superior constrictor muscles which forces the
food to enter deep into the pharynx.
 Deglutition apnea – respiration is reflexly inhibited due to
inhibition of respiratory centres.

118. Reference
 1. Scott-Brown's Otorhinolaryngology and Head and Neck Surgery, Eighth
Edition
 2. Gray’s Anatomy for Students. Second Edition
 3. G.K. Pal Textbook of Medical Physiology. Second Edition.
 4. Cummings Otolaryngology Head and Neck Surgery.
 5. PL Dhingra. Diseases of Ear Nose and Throat.
 6. Chaurasia’s Human Anatomy.

119. THANK YOU