H&N Oral Cavity Anatomy

Question 1

What are the boundaries of the oral cavity?

Answer 1

● Anterior: Vermilion border of the lip
● Posterior/superior: Hard and soft palate junction
● Posterior/inferior: Circumvallate papillae
● Lateral: Anterior tonsillar pillars and glossotonsillar folds

Question 2

What are the anatomical subsites that constitute

the oral cavity?

Answer 2

● Lips: Upper and lower, from vermilion border to buccal
mucosa
● Buccal mucosa: Mucosa lining cheeks and posterior lip
from maxillary and mandibular vestibular folds to the
pterygomandibular raphe (or anterior tonsillar pillars)
● Retromolar trigone: See below
● Alveolar ridges
○ Upper (maxillary): Horizontal hard palate to maxillary
vestibule and superior pterygopalatine arch posteriorly
○ Lower (mandibular): Transition to floor of mouth to
mandibular vestibule to ascending mandibular ramus
posteriorly
● Hard palate: Soft palate to upper (maxillary) alveolar
ridge
● Floor of mouth: Lower alveolar ridge to oral tongue and
anterior tonsillar pillar, divided by the lingual frenulum
anteriorly
● Oral tongue: Anterior two thirds, from circumvallate
papillae to tip

Question 3

What are the anatomical boundaries of the

retromolar trigone?

Answer 3

Mucosa over the ascending mandibular ramus:
● Superior: Maxillary tuberosity
● Anterior: Posterior aspect of the second mandibular
molar
● Lateral: Buccal mucosa
● Medial: Anterior tonsillar pillar

Question 4

Primary oral cavity tumors of which two subsites

have the highest risk for bony invasion?

Answer 4

● Alveolar ridges

● Retromolar trigone

Question 5

Describe the course of the Stensen duct (parotid

duct) from the gland to the oral cavity.

Answer 5

Anterior parotid gland → superficial to the masseter muscle
and buccal fat pad → 90-degree turn to pierce the
buccinator muscle → between the oral mucosa and
buccinators muscle → papilla in buccal mucosa across from
the second maxillary molar

Question 6

Describe the course of the Wharton duct (sub-mandibular duct) from the gland to the floor of the mouth and its relationship to the lingual nerve
along its course.

Answer 6

Anterior “deep lobe” of the submandibular gland →
between the lingual and hypoglossal nerves over the
hyoglossus muscle → anterior and superior ascent between
the genioglossus and sublingual glands → over the lingual
nerve → sublingual papilla just lateral to the lingual
frenulum.

Question 7

What is the arterial supply to the oral cavity?

Answer 7

External carotid artery
● Lingual artery → oral tongue
● Greater palatine artery→ hard palate
● Superior alveolar arteries (anterior, middle, and posterior)
→ gingival of the maxilla, alveolar ridge, teeth, buccal
mucosa
● Transverse facial artery (superficial temporal artery) →
buccal mucosa
● Facial artery → lips (labial arteries)
● Buccal artery (maxillary a) → buccal mucosa
● Inferior alveolar artery → mandible, mandibular teeth
● Ascending pharyngeal artery + lesser palatine arteries →
retromolar trigone, posterior floor of mouth
● Submental (facial artery) and sublingual (lingual artery)
arteries → floor of mouth

Question 8

Describe the venous drainage of the oral cavity.

Answer 8

All sites drain ultimately to the jugular system. The hard

palate drains first through the pterygoid plexus.

Question 9

What is the relationship between the lingual artery
and vein, hypoglossal nerve, and the hyoglossus
and mylohyoid muscles?

Answer 9

From superficial to deep (or lateral to medial):
● Mylohyoid muscle
● Hypoglossal nerve and lingual vein
● Hyoglossus muscle
● Lingual artery
● Genioglossus

Question 10

What nerves provide sensation to the upper and

lower lips?

Answer 10

● Upper lip: Infraorbital nerve (CN V2)

● Lower lip: Mental nerve (CN V3)

Question 11

What is the sensory innervation of the retromolar

trigone?

Answer 11

● Lesser palatine nerves

● Glossopharyngeal nerve (CN IX)

Question 12

What is the sensory innervation of the tongue?

Answer 12

● Anterior two-thirds
○ General sensory: Lingual nerve (CNV3)
○ Special sensory: Chorda tympani nerve via the lingual
nerve (CNV3)
Posterior third
● General and special sensory: Glossopharyngeal nerve (CN
IX).

Question 13

What provides the sensory innervation of the floor

of mouth?

Answer 13

Lingual nerve (CN V3)

Question 14

What provides sensory innervation to the hard

palate?

Answer 14

Nasopalatine nerve (CN V2) via the incisive canal

Question 15

What are the four intrinsic and four extrinsic

tongue muscles?

Answer 15

All muscles are paired and separated in the midline by the
lingual septum:
● Intrinsic tongue musculature: Change the shape of the
tongue
○ Superior longitudinal
○ Inferior longitudinal
○ Transverse
○ Vertical muscles
● Extrinsic tongue musculature
○ Genioglossus
○ Hyoglossus
○ Palatoglossus
○ Styloglossus

Question 16

Which tongue muscle is not innervated by the
hypoglossal nerve (CN XII), and by what is it
innervated?

Answer 16

Palatoglossus muscle is innervated by the pharyngeal

branch of the vagus nerve (CNX).

Question 17

What space is defined medially by the buccinators
muscle and its fascia, the mandible inferiorly, the zygomatic arch superiorly, the risorius, zygomati-
cus major, and levator labii superioris muscles laterally, the orbicularis oris muscle anteriorly, and
the anterior border of the masseter muscle and
the parotid gland posteriorly?

Answer 17

Buccal space

Question 18

What space is defined (1) by the layers of the deep
cervical fascia as they split around the mandible
and come back together at the ventral and dorsal
borders of the mandibular ramus, thus enclosing
the lateral pterygoid muscle; and (2) by the fascia
surrounding the medial pterygoid, masseter and
temporalis muscles?

Answer 18

Masticator space

Question 19

Which lymph node areas usually drain the oral

cavity?

Answer 19

Levels I, II, and III. Drainage pathways to level IV have also
been described.

Question 20

What lymph node basins drain the lips?

Answer 20

● Submandibular lymph nodes (level IB) → upper and lower lip
● Submental lymph nodes (level IA) → lower lip, primarily
midline lesions
● Other: preauricular, parotid, perifacial → upper lip

Question 21

What is the typical lymphatic drainage of the oral

tongue?

Answer 21

● Tip → submental lymph nodes (level IA)
● Ventral tongue → submental and submandibular lymph
nodes (level IA and IB)
● Lateral tongue → submandibular (level IB), jugulodigastric
nodes (level IIA), directly to levels III and IV
Note: Laterality of lymphatic drainage of the oral tongue
due to the lack of lymphatic anastomoses across the fibrous
lingual septum is unique from the base of tongue.

Question 22

What lymph node basin(s) is primarily responsible

for draining the retromolar trigone?

Answer 22

Upper jugular nodes (level IIA)

Question 23

What is the lymphatic drainage for the floor of

mouth?

Answer 23

● Anterior → Level IA and IB (often bilateral)

● Posterior → Level IIA (ipsilateral)

Question 24

What lymphatic basins preferentially drain the

buccal mucosa?

Answer 24

Levels IA and IB

Question 25

Which lymph nodes preferentially drain the hard

palate?

Answer 25

Levels I and II