anatomy of oralcavity

1. Oral Cavity Anatomy

2. • The anterior boundary of the oral cavity is the
skin–vermilion junction.
The superior portion of the oral cavity extends
posteriorlyto the junction between the hard
and soft palate while the inferior portion
extends to the circumvallate papillae.

3. Lip
• The lips begin at the junction of the vermilion
border with the skin and form the anterior
aspect of the oral vestibule.
The lips are composed of the vermilion
surface, which is the portion of the lip that
comes in contact with the opposing lip.

4. • The lips are well defined into an upper and
lower.
The primary motor control of the lips is
provided by the buccal and mandibula
branches of the facial nerve.

5. Oral Tongue
• The anterior two-thirds of the tongue is mobile
and considered part of the oral cavity.
The oral tongue extends anteriorly from the
circumvallate papillae to the undersurface of the
tongue at the junction of the floor of the mouth.
The fibrous septum divides the tongue into right
and left halves.
The oral tongue can be demarcated into four
anatomic areas:
the tip,lateral borders, dorsal surface, and
undersurface (ventralsurface).

6. • There are six pairs of muscles that form the
oral tongue.
Three of these muscles are extrinsic, while the
other three are intrinsic. The extrinsic muscles
include the genioglossus,hyoglossus, and
styloglossus.
The intrinsic muscles include the lingual,
vertical, and transverse muscles.

7. • The former primarily move the body of the
tongue, while the latter alter the shape and
conformation of the tongue during speech and
swallowing.
The blood supply to the tongue is primarily via
the lingual artery, tonsillar branch of the facial
artery, and ascending pharyngeal artery with
primary drainage by the internal jugular vein.
General sensation of the anterior two thirds of
the tongue is supplied by the lingual nerve,

8. • Excluding the circumvallate papillae,
taste fibers from the anterior two thirds of the
tongue run in the chorda tympani branch of
the facial nerve;
the glossopharyngeal nerve provides
sensationand taste to the posterior third of
the tongue and circumvallate papillae.

9. Floor of the Mouth
• The floor of the mouth is a semilunar space
extending from the lower alveolar ridge to the
undersurface of the tongue.
The floor of the mouth overlies the mylohyoid
and hyoglossus muscles.
• The posterior boundary of the floor of the mouth
is the base of the anterior tonsillar pillar.
This region is divided into right and left by the
frenulum of the tongue and contains the ostia of
the submandibular and sublingual salivary glands

10. • A sling formed by the mylohyoid muscles
medially supports the anterior floor of the
mouth, and the hyoglossus supports the
posteriorfloor of the mouth.
The lingual and hypoglossal nerves are lateral
to the hyoglossus, while the lingual artery is
medialto the hyoglossus. Innervation of the
floor of the mouth is provided by the lingual
nerve

11. Hard Palate
• The hard palate extends from the inner
surface of the superior alveolar ridge to the
posterior edge of the palatine bone.
This is a semilunar area between the superior
alveolar ridge and the mucous membrane
covering the palatine process of the maxillary
palatine bones.

12. Alveolar Ridge
• The alveolar ridges include the alveolar
processes of the maxilla and mandible and the
overlying mucosa.
The mucosal covering of the lower alveolar
ridge extends from the line of attachment of
mucosa in the buccal gutter to the line of free
mucosa of the floor of the mouth.

13. • The lower alveolar ridge extends to the
ascending ramus of the mandible posteriorly.
• The superior alveolar ridge mucosa extends
from the line of attachment of mucosa in the
upper gingival buccal gutter to the junction of
the hard palate.
The posterior margin is the upper end of the
pterygopalatine arch.

14. Retromolar Trigone
• The retromolar trigone is the triangular area
overlying theascending ramus of the
mandible.
The base of the triangle is formed by the
posterior most molar, and the apex lies at
themaxillary tuberosity.

15. Buccal Mucosa
• The buccal mucosa includes the mucosal
surfaces of the cheek and lips from the line of
contact of the opposing lips to the
pterygomandibular raphe posteriorly.
This extends to the line of attachment of the
mucosa of the upper and lower alveolar ridge
superiorly and inferiorly.
Innervation is supplied by the buccal nerve, a
branch of the mandibular nerve.

18. Oral cavity; paramedian section
depicting regional anatomy.

19. Oral cavity illustration depicting
regional anatomy

20. pharynx

21. nasopharynx
• The nasopharynx is a cuboidal chamber that is
slightly broader in the transverse dimension
than in the anterior–posterior dimension
Anteriorly it is continuous with the nasal
cavity via the posterior choanae, while
inferiorly it communicates with the
oropharynx.

22. • The roof of the nasopharynx is formed by the
basilar portion of the sphenoid and occipital
bones and the floor by the superior surface of
the soft palate and nasopharyngeal isthmus.

23. • The lateral walls of the nasopharynx contain
the pharyngotympanic tube (Eustachian tube)
openings, which are bounded by a
prominence known as the torus tubarius.
The torus is formed by the cartilage of the
pharyngotympanic tube elevating the mucous
membrane of the lateral nasopharynx.

24. • Posterior to the torus is the pharyngeal recess
otherwise known as the fossa of Rosenmüller.
The lateral walls, including the pharyngeal
recess (fossa of Rosenmüller), are the most
common origin of nasopharyngeal
malignancies

25. • The posterior wall of the nasopharynx
contains the superior
• pharyngeal constrictor muscle,
pharyngobasilar fascia, and
• buccopharyngeal fascia.

26. • The superior pharyngeal constrictor only
extends superiorly
• to the skull base in the midline, and laterally
the pharyngobasilar
• fascia serves to attach the constrictor muscle
to the
• base of the skull at the basiocciput and
petrous portion of
• the temporal bone.

27. • This lateral area of muscular deficiency is
• otherwise known as the sinus of Morgagni,
through which the
• pharyngotympanic tube and levator veli
palatini pass.

28. • The pharyngobasilar fascia is continuous with
the foramen lacerum and is in close proximity
to the foramen ovale, foramen spinosum,
jugular foramen, hypoglossal canal, and
carotid space

29. • The proximity of these foramina to the sinus
of Morgagni assumes importance in the
consideration of intracranial extension

30. • The afferent innervation of the nasopharynx
anterior to the pharyngotympanic tube orifice
is provided by the maxillary division of the
trigeminal nerve (V2), and posterior to the
tubal orifice by the glossopharyngeal nerve.

31. • Venous drainage is provided by the
pharyngeal plexus, which drains into the
internal jugular veins directly or via
communication with the pterygoid plexus

32. Pathways for lymphatic spread of
nasopharyngeal carcinoma

33. major lymph collectors of the
nasopharynx

34. (MRI) of the head, showing the
nasopharynx and related structures

35. Basal view of skull illustrating the
foramina of the base of the skull

36. Axial CT scan illustrating the
bony anatomy.

38. Oropharynx
• The oropharynx is contiguous with the oral
cavity anteriorly, the larynx and hypopharynx
posterior-inferiorly, and superiorly with the
nasopharynx. Three main subregions compose
the oropharynx including the tonsil, base of
tongue, and soft palate.
• Normal function of the oropharynx is critical
for speech and swallowing.

39. • The tonsillar region contains the anterior and
posterior tonsillar pillars as well as the
palatine tonsil

40. TONSILS
• The palatine tonsils are lymphoid aggregates
incompletely encapsulated with a keratinized
stratified squamous epithelial mucosal lining
positioned in the tonsillar bed, which is a part
of the tonsillar cleft between the anterior
(palatoglossal) and posterior
(palatopharyngeal) tonsillar pillars.

41. BASE OF TONGUE
• The base of tongue comprises the posterior
third of the tongue and is bounded anteriorly
by the circumvallate papillae, sitting in front of
the sulcus terminalis.

42. • The base of tongue is bounded posterior-
inferiorly by the hyoid and epiglottis and
laterally by the glossopharyngeal sulci.
Underlying the mucosa of the base of tongue
are lymphatic nodules collectively known as
the lingual tonsil.

43. • The vallecula is a 1-cm mucosal strip that
serves as a transition between the base of
tongue and epiglottis and is considered a part
of the base of tongue

44. • The sensory innervation of the base of tongue
is via the glossopharyngeal nerve (cranial
nerve [CN] IX) with a small aspect of the base
of tongue supplied by the internal laryngeal
nerve (CN X)

45. • The soft palate is a fibromuscular structure
bounded anteriorly by the hard palate,
laterally coursing into the anterior tonsillar
pillars and posterior-inferiorly forming a free
edge, and the midline uvula.

46. • The soft palate is composed of five muscles
(levator veli palatini, tensor veli palatini,
palatoglossus, palatopharyngeus, and
musculus uvulae) posteriorly and the palatine
aponeurosis an expanded tendon of the
tensor veli palatini anteriorly

47. • The muscles of the soft palate are supplied
through the pharyngeal plexus (which is
composed of the pharyngeal branches of CNs
IX and X, as well as sympathetic branches from
the superior cervical ganglion,

48. • Except for the tensor veli palatini, which is
supplied by CN V2). The sensory supply is from
CN IX.

49. • The oropharynx serves many functions,
including that of degustation, respiration, and
speech. Advanced tumors arising in the
oropharynx can infiltrate muscles and nerves,
thus significantly impeding these functions. A
major goal of successful therapy is to limit the
impact of the treatment on long-term
function.

50. Hypopharynx
• The hypopharynx, sometimes referred to as
the laryngopharynx, is contiguous superiorly
with the oropharynx and inferiorly with the
cervical esophagus.
As general landmarks, the superior border of
the hypopharynx is demarcated by the hyoid
bone and the inferior border by the cricoid
cartilage.

51. • With regard to cancer diagnosis and staging,
there are
• three primary anatomic subsites within the
hypopharynx:
the bilateral pyriform sinuses, the postcricoid
region, and the posterior pharyngeal wall

52. • The pyriform sinuses are essentially inverted
pyramids with the medial, lateral, and anterior
walls narrowing inferiorly to form the apices.
Posteriorly, the pyriform sinuses are open and
contiguous with the pharyngeal walls

53. • Superiorly, the sinuses are surrounded by the
thyrohyoid membrane through which passes
the internal branch of the superior laryngeal
nerve ,Tumor involvement of the sensory
branches of this nerve can result in referred
otalgia

54. • The postcricoid region is comprised of the
mucosa overlying the cricoid cartilage, with
the arytenoid and esophageal mucosa forming
the superior and inferior borders, respectively.

55. • The posterior pharyngeal wall predominantly
comprises the squamous mucosa covering the
middle and inferior pharyngeal constrictor
muscles and is separated from the
prevertebral fascia by the retropharyngeal
space.

56. • Typically, the mucosa lining the pharyngeal
wall is <1 cm in thickness and provides a
minimal barrier to direct tumor infiltration.
The posterior pharyngeal wall is contiguous
with the lateral wall of the pyriform sinus

57. • Sensory innervation of the hypopharynx is
provided by the internal branch of the
superior laryngeal nerve as well as fibers
deriving from the glossopharyngeal nerve.

58. • The recurrent laryngeal nerve and the
pharyngeal plexus provide the primary motor
supply.
The arterial supply of the hypopharynx is
derived primarily from branches of the
external carotid artery: superior thyroid
arteries, ascending pharyngeal arteries, and
lingual arteries.

59. • There is a rich network of lymphatics within
the hypopharynx that drain directly through
the thyrohyoid membrane and into the
jugulodigastric lymph nodes, most commonly
involving the subdigastric node.

60. • Additionally, there may be direct drainage into
the spinal accessory nodes.
Tumors involving the posterior pharyngeal
wall can also drain to the retropharyngeal
nodes, including the most cephalad
retropharyngeal nodes of Rouviere

62. larynx
• The larynx is divided into the supraglottis,
glottis, and subglottis.
The supraglottis consists of the epiglottis, false
vocal cords,ventricles, aryepiglottic folds, and
the arytenoids.
The glottis includes the true vocal cords and
the anterior commissure.
The subglottis is located below the vocal cords

63. • The lateral line of demarcation between the
glottis and supraglottic larynx is the apex of
the ventricle.
The demarcation between the glottis and
subglottis is ill defined, but the subglottis is
considered to extend from a point 5 mm
below the free margin of the vocal cord to the
inferior border of the cricoid cartilage or 10
mm below the apex of the ventricle.

64. • The vocal cords vary from 3 to 5 mm in
thickness and terminate posteriorly with their
attachment to the vocal process.
The posterior commissure is the mucosa
between the arytenoids

65. • The shell of the larynx is formed by the hyoid
bone, thyroid cartilage, and cricoid cartilage;
the cricoid cartilage is the only complete ring.

66. • The more mobile interior framework is
composed of the heart-shaped epiglottis and
the arytenoid, corniculate, and cuneiform
cartilages.
The corniculate and cuneiformcartilages
produce small, rounded bulges at the
posterior end of each aryepiglottic fold.

67. • The thyroid and the cricoid cartilages and a
portion of the arytenoid cartilage are hyaline
cartilage and may partially ossify with age,
particularly in men.

68. • The epiglottis is elastic cartilage;
• ossification does not occur, and even focal
calcification is rare

69. • The external laryngeal framework is linked
together by the thyrohyoid, the cricothyroid, and
the cricotracheal ligaments or membranes
The epiglottis is joined superiorly to the hyoid
bone by the hyoepiglottic ligament.
The epiglottis is joined to the thyroid cartilage by
the thyroepiglottic ligament at a point just below
• the thyroid notch and above the anterior
commissure.

70. • The arrangement of the ligaments that
connect the cricoid and arytenoid cartilages
and form the vocal ligaments, which are part
of the true vocal cords,

71. • The conus elasticus (cricovocal ligament) is the
lower portion of the elastic membrane that
connects the inferior framework.
It connects the upper surface of the cricoid,
the vocal process of the arytenoid,and the
lower thyroid cartilage; its free border is
thickened into the vocal ligament.

72. • The vocal ligaments and muscles attach to the
vocal process of the arytenoid posteriorly and
the thyroid cartilage anteriorly.
• The intrinsic muscles of the larynx, which
primarily control the movement of the cords,

73. • The extrinsic muscles are concerned primarily
with swallowing.
The cricothyroid muscle produces tension and
elongation of the vocal cords and is innervated
by the superior laryngeal nerve

74. • The pre-epiglottic and paraglottic fat spaces
are essentially one contiguous space lying
between the external framework of the
thyroid cartilage and hyoid bone and the inner
framework of the epiglottis and intrinsic
muscles.

75. • Lam and Wong showed that there are thin
membranous septa between the
paraglotticand pre-epiglottic spaces that are
capable of holding a tumor in check to a
limited degree.
The space is traversed by blood and lymphatic
vessels and nerves.

76. • Because few capillary lymphatics arise in this
area, invasion of the fat space should only
indirectly be associated with lymph node
metastases.

77. • The fat space is limited by the conus elasticus
inferiorly, the thyroid ala, the thyrohyoid
membrane, the hyoid bone anterolaterally,
the hyoepiglottic ligament superiorly, and the
fascia of the intrinsic muscles on the medial
side. Posteriorly, it is adjacent to the anterior
wall of the pyriform sinus.

78. • The laryngeal surface of the epiglottis and the
free margin of the vocal cords are squamous
epithelium, and the remainder is usually
pseudostratified ciliated columnar epithelium.

79. • Beneath the epithelium of the free edge of
the vocal cord is the lamina propria, which can
be divided into three layers.
There is no true submucosal layer along the
free margin of the vocal fold. The laryngeal
arteries are branches of the superior and
inferior thyroid arteries.

80. • The intrinsic muscles of the larynx are
innervated by the recurrent laryngeal nerve.
The cricothyroid muscle—an intrinsic muscle
responsible for tensing the vocal cords—is
supplied by a branch of the superior laryngeal
nerve;

81. • isolated damage to this nerve causes a bowing
of the true vocal cord, which continues to be
mobile, but the voice may become hoarse.

82. • The supraglottic structures have a rich
capillary lymphatic plexus; the trunks pass
through the pre-epiglottic space and the
thyrohyoid membrane and terminate mainly
in the subdigastric (level II) lymph nodes; a
few drain to the middle internal jugular chain
(level III) lymph nodes

83. • There are essentially no capillary lymphatics of
the true vocal cords; as a result, lymphatic
spread from glottic cancer occurs only if
tumor extends to supraglottic or subglottic
areas.

84. • The subglottic area has relatively few capillary
lymphatics.
• The lymphatic trunks pass through the
cricothyroid membrane to the pretracheal
(Delphian) lymph nodes in the region of the
thyroid isthmus.

85. • The subglottic area also drains posteriorly
through the cricotracheal membrane, with
some trunks going to the paratracheal (level
VI) lymph nodes and others continuing to the
inferior jugular (level IV) chain.

86. Diagrammatic sagittal section of the
larynx.

87. Cross section of the larynx at the level
of the vocal cords.

88. Framework of the larynx

92. CLASSIFICATION
• Upper horizontal chain of nodes: Submental ,
Submandibular ,Parotid, Postauricular,
Occipital

94. SUBMENTAL NODES
• Lie on mylohyoid muscle in the submental
triangle .
2 to 8 in number
Drainage –afferents come from the chin,
middle part of lower lip, anterior gums,
anterior floor of mouth and tip of tongue.
Efferents -they go to submandibular and
internal jugular chain

96. SUBMANDIBULAR NODES
• They lie in submandibular triangle in relation
to submandibular gland.
Afferents come from lateral part of the lower
lip, upper lip, cheek,nasal vestibule and
anterior part of nasal cavity, gums,teeth
medial canthus, soft palate, anterior pillar,
anterior part of tongue, submandibular and
sublingual salivary glands and floor of mouth
Efferents go to internal jugular chain

97. PAROTID NODES
• They lie in relation to the parotid salivary
gland.
Afferents come from the scalp,pinna, external
auditory canal,face,buccal mucosa.
Efferents go to internal jugular or external
jugular chain

99. POST AURICULAR NODES
• Also called as mastoid nodes
They lie behind the the pinna over the
mastoid.
Afferents come from the scalp, posterior
surface of pinna and skin of mastoid.
Efferents drain into internal jugular chain

101. OCCIPITAL NODES
• They lie at the apex of the posterior triangle
Afferents come from scalp, skin of upper neck.
Efferents drain into upper accessory chain of
nodes

103. Lateral cervical nodes
• They include nodes, superficial and deep to
sternocleidomastoid muscle and in the
posterior triangle.
Superficial external jugular group
Deep group i. Internal jugular chain
(upper,middle and lower groups) ii. Spinal
accessory chain iii.Transverse cervical chain

105. LATERAL CERVICAL NODES
• a) Superficial group – it lies along external
jugular vein and drains into internal jugular
and transverse cervical nodes
b)Deep group It consists of three chains, the
internal jugular, spinal accessory and
transverse cervical

106. Internal jugular chain
• Lymph nodes of internal jugular chain lie
anterior, lateral and posterior to internal
jugular vein.
Upper group (jugulodigastric node) – drains
oralcavity,orpharynx,nasopharynx,hypopharyn
x, larynx and parotid.
Middle group drains hypopharynx, larynx,
throid, oral cavity, oropharynx.
Lower jugular group drains larynx, thyroid and
cervical oesophagus

107. Spinal accessory chain
• Lies along the spinal accessory nerve.
Spinal accessory chain drains the scalp, skin of
the neck, the nasopharynx, occipital and
postauricular nodes.
Efferents from this chain drain into transverse
cervical chain

108. Transverse cervical chain
(supraclavicular nodes)
• It lies horizontally, along the trasverse cervical
vessels, in thelower part of the posterior
triangle.
The medial nodes of the group are called
scalene nodes.
Afferents to those nodes come from the
accessory chain and also infraclavicular
structures,e.g. breast, lung, stomach, colon,
ovary and testis

109. Anterior cervical nodes
• Anterior jugular chain and Juxtavisceral chain
i. Prelaryngeal ii. Pretracheal iii. Paratracheal

110. ANTERIOR CERVICAL NODES
• They lie between the two carotids and below
the level of hyoid bone and consist of two
chains: (a) Anterior jugular chian It lies along
anterior jugular vein and drains the skin of
anterior neck.
(b) Juxtavisceral chain

111. • It consists of prelaryngeal,pretracheal and
paratracheal nodes (i) Prelaryngeal node
(Delphian node)-lies on cricothyroid membrane
and drains subgottic region of larynx and
pyriform sinuses (ii) Pretracheal nodes lie in front
of the trachea, and drain thyroid gland and the
trachea.Efferents from these nodes go to
paratracheal, lower internal jugular and anterior
mediastinal nodes (iii) Paratracheal Nodes – drain
the thyroid lobes, subglottic larynx, tracha and
cervical oesophagus

114. CLASSIFICATION OF NECK NODES
ACCORDING TO LEVELS
• Level I Submental (IA) Submandibular (IB)
Level II Upper jugular Level III middle jugular
Level IV Lower jugular
LeveV Posterior triangle group(Spinal
accessory and transverse cervical chains)
LevelVI Prelaryngeal Pretracheal Paratracheal
LevelVII Nodes of upper mediastinum

117. Level I
• IA Submental nodes, which lie in the
submental triangle i.e. between right and left
anterior bellies of diagastric muscles and the
hyoid bone.
IB Submandibular ones, lying between
anterior and posterior bellies of diagastric
muscle and the body of mandible

119. Level II – Upper Jugular Nodes
• They are located along the upper third of
jugular vein I.e. between the skull base above,
and the level of hyoid bone (or bifurcation of
carotid artery) below

121. Level III – Middle Jugular Nodes
• They are located along the middle third of
jugular vein, from the level of hyoid bone
above, to the level of upper border of cricoid
cartilage

122. Level IV – Lower Jugular Nodes
• They are located along the lower third of
jugular vein; from upper border of cricoid
cartilage to the clavicle

123. Level -V – Posterior Cervical Group
• They are located in the posterior triangle i.e.
between posterior border of
sternocleidomastoid(anteriorly), anterior
border of trapezius (posteriorly), and the
clavicle below.They include lymph nodes of
spinal accessary chain,transverse cervical
nodes and supraclavicular nodes

124. LevelVI Anterior Compartment
Nodes
• They are located between the medial borders
of sternocleidomastoid muscles (or carotid
sheaths) on each side, hyoid bone above and
superasternal notch below.They include
prelaryngeal,pretracheal, paratracheal nodes

125. LevelVII
• They are located below the suprasternal notch
and include nodes of the upper mediastinum