L9: Nasal cavity

Question 1

Nasal cavities (3)

Answer 1

Nasal vestibule: small dilated space and lined w skin and contains hair

Respiratory region: largest part, rich neurovascular supply, lined by respiratory epithelium (ciliated and mucus cells)

Olfactory: small part at apex of cavity, lined by olfactory epithelium and contains olfactory receptors

Question 2

General parts of external nose and relevance

Answer 2

Bony part and cartilaginous part
Cartilaginous part operated on by plastic surgeons
Cartilage form growth plates of nose - if damaged as a baby, nose may not grow as it should

Septal cartilage - trauma to cartilage can cause bleed within, cutting off blood supply to the cartilage –> loss of part of nose (nasal septal hematoma)

Question 3

Floor

Answer 3

Same as roof of oral cavity
Consists of: palatine process of maxilla and horizontal plate of palatine
(maxilla and palatine bones form nasal crest which articulates w nasal septum)

Question 4

Roof

Answer 4

Important in fracture 
- Nasal bone (most commonly 
  fractured)
- Frontal bone w nasal spine
- Cribriform plate (ethmoid 
  bone)
- Sphenoid bone

Question 5

Ethmoid bone

Answer 5

Formed by:
- Cribriform plate
- Crista galli
- Perpendicular plate
- L and R ethmoidal labyrinth
- Orbital plate
- Superior and middle conchae
- Uncinate process
- Infundibulum = 
  communication 
  between sinuses and nasal 
  cavity

Question 6

Medial wall

Answer 6

= nasal septum
- Septal nasal cartilage 
  anteriorly 
- Posteriorly mainly vomer and 
  perpendicular plate of 
  ethmoid bone
- Small contributions by nasal 
  bones where they meet at 
  midline and nasal spine of 
  frontal bone
- Nasal crests of maxillary and 
  palatine bone

Can get nasal septal hematoma

Question 7

Lateral wall

Answer 7

- Ethmoid bone (sup and 
  middle conchae)
- Inferior concha (separate 
  bony structure)
- Nasal bone 
- Frontal bone
- Perpendicular plate of 
  palatine bone
- Lateral process of septal 
  cartilage
- Major and minor ala cartilage
- Medial pterygoid plate of 
  sphenoid bone
- Lacrimal bone (impt in 
  drainage) 

Sinuses drain into lateral wall

Question 8

Where do sphenoidal sinuses drain?

Answer 8

Drain along top of nasal cavity
(Sits just under pituitary so e.g. pituitary tumour can be accessed via this sinus)
Drains into spheno-ethmoidal recess

Question 9

Where do posterior ethmoidal air cells drain to?

Answer 9

Opening into lateral wall of superior meat (just deep to superior concha)

Question 10

Which sinuses drain to lateral wall of middle meatus?

Answer 10

Frontal sinus, anterior and middle ethmoidal air cells, maxillary sinuses

Question 11

Where does nasolacrimal duct drain to?

Answer 11

Opens just deep to inferior concha

Question 12

Innervation of sinuses

Answer 12

Innervated by branches of trigeminal n [V]

Frontal sinus: V1
Maxillary: V2
Ethmoidal cells: V1 and V2
Sphenoid: V1 and V2

Question 13

8 bones of nasal cavity

Answer 13

Unpaired:
Ethmoid
Sphenoid
Frontal
Vomer

Paired:
Nasal
Maxillary
Palatine
Lacrimal
Inferior concha

Question 14

What enters and exit via cribriform plate?

Answer 14

• [I] fibres
• Ant ethmoidal n of [V1] and
  accompanying vessels
• Nasal veins connecting to
  superior sagittal sinus

Question 15

What enters and exits via sphenopalatine foramen?

Answer 15

• Sphenopalatine branch of
  maxillary a
• Nasopalatine branch of [V2]
• Sup nasal branches of [V1]

Question 16

What enters and exits via incisive canal?

Answer 16

• Nasopalatine n
• Terminal part of greater
  palatine a

Question 17

Small foramina in lateral wall

Answer 17

• A branch of infraorbital n [V2]
• A branch of greater palatine
  n [V2]

Question 18

Lymph drainage

Answer 18

Runs w veins rather than arteries, drains to submandibular, deep cervical and retropharyngeal nodes

Question 19

Venous drainage

Answer 19

• Nasal v in foramen cecum
• Drainage to cavernous sinus
  in nasal cavity
• Drainage to pterygoid plexus
  in infratemportal fossa
  Drainage to facial v

Question 20

Common site of anterior epistaxis

Answer 20

Littles area - area of signficant anastomoses = prone to nosebleeds

• Main artery: sphenopalatine a (end of maxillary a passing through sphenopalatine foramen)
• Septal branch of superior labial
• Ascending branch of greater palatine
• Septal branches of anterior and posterior ethmoidal a

Anastomosis over lower anterior part of septum (Littles area) and form Kieselbach’s plexus

Question 21

Posterior epistaxis

Answer 21

Most commonly sphenopalatine a

Question 22

Innervation

Answer 22

[I], [V1], [V2]
parasymp [VII]
sympa [T1]