L10.3 Oral Cavity

Question 1

Boundaries of the oral cavity

Answer 1

• Roof: Maxilla
• Floor: Mandible
  
  • Mandible articulates with the temporal bone (sliding hinge joint → chewing)
  • Msucles help with mastication, and also form wall of cavity
• LAT: Buccinator

Question 2

Mastication muscles

Answer 2

• (innervated by trigeminal N)
• Temporalis
• Massester

Question 3

Facal expression muscles

Answer 3

• (By facial N)
• Orbicularis oris (around lips)
• Buccinator (closes space b/w mandible and maxilla)

Question 4

Roof of the mouth

Answer 4

• Hard palate
  
  • Palatine process
  • Horizontal process of palatine bone (Posteriorly)
• Soft palate (behind the hard palate)
  
  • Covered by muscles and connective tissues
• Palatine glands

Question 5

Features of the palatine glands

Answer 5

• Deep to mucosa
  
  • Mucosa continues throughout the whole of oral cavity (lines tongue as well)
• Deeper = hard/soft palate
• BV runs under mucosa
  
  • Lesser palatine N & A → POS to Soft palate
  • Greater palatine N & A → along hard palate
    
    • N project up in the incisor foramen (ANT) into INF quadrant of the nasal cavity

Question 6

Floor of the mouth

Answer 6

• POS part → Rami of mandible → projecting up to temporal mandibular joint
• Mandible deficient INF → covered by mylohyoid muscle
  
  • Attaches to mandible and hyoid bone
• N coming from base of skull → through foramen ovale → branch into different branches to oral cavity
• Hyoid bone
  
  • Sits inbetween floor of mouth and neck

Question 7

Oral vestibule

Answer 7

• Space b/w dental arches where mucosa is reflected down
• Allows food in and storing while chewing

Question 8

Sulcus terminalis

Answer 8

• splits tongue into ANT 2/3 and POS 1/3

Question 9

Foramen caecum

Answer 9

• Depression at the apex;
• remnant of the thyroglossal duct (closes at birth)

Question 10

Arches projecting from the tongue and the location of the palatine tonsils

Answer 10

• Palatopharyngeal arch
• Palatoglossal arch
  
  • Palatine tonsils found in b/w the arches
  • Chronic inflammation → closes cavity for food and makes it difficult to breath

Question 11

4 different papillae found on the tongue

Answer 11

• (swellings on dorsal surface of tongue)
• Valate → ANT to sulcus terminalis, lining up in a row
• Foliate → grooves at LAT-POS part
• Fungiform → scattered around ANT 2/3 of tongue
  
  • Fungiform papillae is very vascular
• Filiform → to make tongue rougher → for food

Question 12

Where are tastebuds found

Answer 12

• Tastebuds are embedded in the walls of the papillae
• Connected to sensory N that run in chorda tympani→ branch of CN7
• NOT found in filiform papillae (which are sharp and pointy)

Question 13

Extrinsic muscles of the tongue

Answer 13

External attachments of the tongue (paired on each side) → altering position

• Palatoglossus
  
  • Palate above → tongue
  • Elevate tongue
  • NOT innervated by CN12, but by vagus instead
• Styolglossus (POS)
  
  • Styloid process → tongue (more horizontal)
  • Retracts tongue
• Hyoglossus
  
  • Hyoid bone → underneath of tongue
  • Depress tongue
• Genioglossus
  
  • Genial tubercle (POS mandible in midline) → back end of tongue
  • Protraction of tongue

Question 14

Innervation of the extrinsic muscles of the tongue

Answer 14

• CN12 EXCEPT for palatoglossus (By branch of vagus)
• N damage → tongue deviates to the side of the lesion when protracted tongue
  
  • Due to unopposed action of genioglossus on the other side

Question 15

Intrinsic muscles of the tongue

Answer 15

• Have attachments within the tongue → altering the shape of the tongue
  
  • SUP longitudinal
  • INF longitudinal
  • Transverse & vertical

Question 16

Innervation of the tongue

Answer 16

• Motor entirely by CN12 - hypoglossal (ex and intrinsic - except palatoglossal)
• Sensory
  
  • POS 1/3
    
    • Entirely glossopharyngeal
    • Taste and general sensory (touch/pressure)
  • ANT 2/3
    
    • Chorda tympani (branch of CN7)
    • Lingual N (3rd div of trigeminal N)

Question 17

What innervates each arch of teeth

Answer 17

• Maxillary arch → Innverated by SUP alveolar N (maxillary div of trigeminal N)
• Mandible arch → by INF alveolar N (mandibular div of trigeminal N, access into mandible via mandibular foramen)
  
  • Mandibular foramen found on internal surface of rami

Question 18

Features and number of teeth

Answer 18

• Shape adapted to function
• In each half of the arches
  
  • Central incisor and LAT incisor (cutting food)
  • Canine (anchoring to food)
  • 2 premolar
  • 3 molars
    
    • Both important for grinding

Question 19

Structure of a tooth

Answer 19

• Crown
  
  • Outer layer above gums
  • consists of enamel (protective)
• Dentin
  
  • b/w pulp and enamal
  • Have tubules to transmit fluid to pulp
• Pulp
  
  • Inner core
  • very neurovascular

Question 20

Age of teeth eruption

Answer 20

• Erupt from 6-7yo → 17-25yo
  
  • From ANT to POS
    
    • Except for lower canine and 1st molar (out of sequence)
  • Useful for age identification in forensics
• No room for wisdom teeth to erupt in the mandible
  
  • Erupt sideways → impact on 2nd molar

Question 21

Salivary glands

Answer 21

• Produce saliva (mucous or serous)
  
  • Important for lubricating food, have microbials, enz

Question 22

Parotid salivary glands

Answer 22

• ANT to auditory meatus
• Superficial to messeter
• Single duct in ANT over messeter → opens into oral vestibule in 2nd molar tooth

Question 23

Sublingual salivary glands

Answer 23

• Floor of mouth
• Open via multiple ducts

Question 24

Submandibular salivary glands

Answer 24

• On both sides of POS side of oral cavity
• Around POS edge of mylohyoid muscles
• Duct → projects forward and opens via lingual frenulum

Question 25

Other structures in the floor of the mouth

Answer 25

• Lingual A & V
  
  • Vascular sublingually
  • Important for absorption of drugs in sublingual abs
• Lingual and hypoglossal N
• ∴Damage to floor of mouth
  
  • Perfused bleeding
  • Damage lingual N and hypoglossal N