Oral Cavity

Question 1

Structure of oral cavity

Answer 1

Roof: hard and soft palates
Floor: mainly soft tissues, including tongues
Lateral wall: cheeks

The cavity is separated into:
- oral vestibule: anteriorly to teeth but behind lips
- oral cavity proper: area behind teeth

Anteriorly is opening of oral cavity (oral fissure) created by lips and posteriorly is oropharynx

Question 2

Structure of tongue

Answer 2

Is predominately muscle (4 intrinsic and 4 extrinsic)

Dorsal tongue is covered by lingual papillae 4 types
- fungiform
- foliate
- vallatae
- filiform

The terminal sulcus divides the tongue into an anterior 2/3 (oral) and posterior 1/3 (pharyngeal)

Question 3

Extrinsic muscles of the tongue

Answer 3

Extrinsic muscles alter position while intrinsic alter shape.

Palatoglossus: origin from palatine aponeurosis to insert in tongue. Elevate root of tongue. Innervated by vagus nerve

Styloglossus: from styloid process to tongue. Retracts and elevates tongue. Innervated by Hypoglossal.

Hyoglossus: from hyoid bone to tongue. Depresses and retracts tongue. Innervated by hypoglossal

Genioglossus: from chin to tongue. Depresses or protrudes tongue. Innervated vis hypoglossal

Question 4

Structure of hard palate

Answer 4

Anterior 3/4 is formed palatine process of maxilla and posterior 1/4 by horizontal process of palatine bones and overlying mucosa

Anterior to palatine rugae is incisive papilla which overlies incisive canals

Question 5

Structure of soft palate

Answer 5

Muscular continuation of hard palate that acts to close the oropharyngeal isthmus or separate the oro- and naso-pharynx

Question 6

Palate muscles motor control

Answer 6

Via vagus nerve except for tensor veli palatini which is supplied by mandibular nerve CN V3

Question 7

Palate blood supply

Answer 7

Greater palatine supplies the hard palate

Lesser palatine supplies the soft palate

Question 8

Nerve supply to tongue

Answer 8

Motor: hypoglossal except for palatoglossus which is by vagus

General sensory to anterior 2/3 of tongue: lingual nerve

Taste sensation to anterior 2/3 of tongue: facial nerve via chorda tympani

General and taste sensation to poster 1/3 of tongue: Glossopharyngeal

Question 9

Blood supply and venous drainage of tongue

Answer 9

Lingual artery

Deep lingual and dorsal lingual veins drain the tongue to IJV

Question 10

Structure of pharynx

Answer 10

Tube of fibrous and muscular tissue lies posterior to

• nasal cavity (nasopharynx)
• oral cavity (oropharynx)
• larynx (laryngopharynx)

Question 11

Function of tonsils

Answer 11

Lymphoid tissue found in several places forming Waldeyers ring

• pharyngeal tonsils
• tubal tonsils
• palatine tonsils
• lingual tonsils

Protection ring to fight infections

Question 12

Pharyngeal elevators

Answer 12

Descend from skull to fan out into the inner surface of the pharynx

Salpinogopharyngeus
- extends from Eustechian tube to lateral wall of pharynx. Elevates the pharynx and larynx. Innervation by vagus

Palatopharyngeus
- part of the soft palate and posterior part of the pharynx. Elevates the pharynx and larynx. Draws the soft palate downwards. Supplied by vagus.

Stylopharyngeus
- originates from styloid process and inserts into the pharynx
- elevates the pharynx and larynx during swallowing
- supplied by Glossopharyngeal

Question 13

Pharynx Innervation

Answer 13

Motor and sensory Via pharyngeal plexus and receives branches of CN IX and X

Sensory also from Glossopharyngeal

Parasympathetic secretomotor Innervation by CN X and pterygopalatine ganglion CN VII via CN V2

Question 14

Gag reflex Innervation

Answer 14

Afferent CN IX and efferent CN X

Question 15

major salivary glands

Answer 15

Parotid
Submandibular
Sublingual

Question 16

Submandibular gland

Answer 16

Function: contribute to production of saliva to lubricate oral cavity and aid in chemical digestion of food.

Found along mandible between mylohyoid and hyoglossus

Submandibular duct supply is by submental arteries and drainage by sub mental veins

Blood supply via ECA via facial and lingual arteries

Question 17

Sublingual gland

Answer 17

Lies in floor of mouth between the mandible and hyoglossus lateral to submandibular duct. Sits in sublingual fossa.

Sublingual ducts drain into the oral cavity
Blood supply via submental and sublingual arteries and drainage via submental veins

Question 18

Sublingual and Submandibular gland secretomotor Innervation

Answer 18

Parasympathetic Innervation

• preganglionic parasympathetic fibres travel to submandibular ganglion from the chorda tympani and via the lingual nerve
• post ganglionic parasympathetic fibres then travel in the lingual nerve to the sublingual gland OR travel directly to the sublingual and submandibular glands

Sympathetic Innervation
- derived from the superior cervical ganglia and nerve plexus of ECA

Question 19

Minor salivary glands

Answer 19

Buccal
Palatine
Lingual
Labial

These glands are susceptible to mucoceles (swelling due to blockage of associated ducts)

Question 20

Secretomotor Innervation on minor salivary glands (above oral fissure)

Answer 20

Parasympathetic Innervation (secretomotor to produce saliva)

• Preganglionic parasympathetic fibres travel to pterygopalatine ganglion in the greater petrosal nerve (CN VII nervus intermedius)
• post ganglionic fibres travel to the palate via the palatine nerves

Question 21

Secretomotor Innervation to minor salivary glands (below oral fissure)

Answer 21

Parasympathetic Innervation fibres travel to submandibular ganglion from the chorda tympani and via the lingual nerve

Post ganglionic parasympathetic fibres then travel in the lingual nerve (CN V3) to the glands or travel directly to the glands (not in a nerve)

Question 22

Pathologies of minor salivary ducts/glands

Answer 22

Mumps
- viral infection in children
- painful swellings over salivary glands

Salivary stones (sialothiasis)
- present with pain, swelling and lack of salivation
- most common in submandibular ducts

Excessive salivation
- occurs prior to vomiting
- or related to other disease processes