The Nose & Paranasal Sinuses

Question 1

Describe the external nose

Answer 1

• Made up of two parts:
  
  • Nasal bones
  • Nasal (alar) cartilages
• Naris = external nasal aperture

NB: hairy skin extends into the nasal cavity a short distance - this is the vestibule of the nose

Question 2

Describe the nasal bones

Answer 2

• Superiorly: meet in the midline
• There is an opening inferior to the bones (between the maxillae)
  
  • Maxillae meet inferiorly to form the lower boundary of the opening

Question 3

Describe the nasal cartilages

Answer 3

• Hyaline cartilage
• Attach to the edge of the nasal opening
• Major alar cartilages form lateral boundary of the naris anteriorly
  
  • Fibrofatty tissue forms it posteriorly
• Form anterior septum

Question 4

What forms the medial walls of the nasal cavity?

Answer 4

• Nasal septum - divides cavity in two formed by:

1. Perpendicular plate of the ethmoid superiorly
2. Cartilage anteriorly
3. Vomer posteriorly

Little’s area = highly vascularised area in anterior nasal septum, inflammation causes epistaxis (nosebleeds)

Question 5

Describe the roof of the nasal cavity

Answer 5

• The roof is arched, formed from:

1. Nasal bones anteriorly
2. Cribriform plate in the middle
3. Inferior surface of sphenoid (body) posteriorly

Question 6

What forms the floor of the nasal cavity?

Answer 6

• Palatine processes of the maxillae anteriorly
• Horizontal plate of the palatine bones posteriorly

(i.e. the hard palate)

Question 7

What forms the lateral walls of the nasal cavity?

Answer 7

Maxilla & three concha

Question 8

Discuss the nasal conchae

Answer 8

• Large, medially-directed bony elements
• Covered in highly vascular mucous membranes
  
  • Warm & humidify air as it’s drawn past
• Shelf-like, beneath each is a meatus

NB: superior/middle are part of ethmoid, inferior is a separate bone

Question 9

Where does the sphenoid sinus open into the nasal cavity?

Answer 9

Sphenoethmoidal recess

Question 10

What opens into the superior meatus?

Answer 10

Posterior ethmoidal air cells

Question 11

What opens into the middle meatus?

Answer 11

1. Anterior & middle ethmoidal air cells
2. Frontal sinus
3. Maxillary sinus

Question 12

What opens into the inferior meatus?

Answer 12

Nasolacrimal duct

Question 13

Discuss the blood supply to the nasal cavity

Answer 13

Three sources:

1. Sphenopalatine branch of the maxillary artery (predominant)
2. Anterior ethmoidal branch of ophthalmic artery
3. Labial branch of the facial artery

Question 14

Venous drainage of the nasal cavity

Answer 14

Veins follow artery to drain to:

• Facial vein
• Ophthalmic vein
• Sphenopalatine vein - part of pterygoid plexus

Question 15

Discuss the mucous membrane of the nasal cavity

Answer 15

• Olfactory part: roof and adjacent part of walls
• Vestibule: stratified squamous
• Rest: respiratory epithelium

Question 16

Discuss the nerve supply to the nasal cavity

Answer 16

• Olfactory n. from olfactory mucous membrane
  
  • Pass through cribriform plate
• General sensation: branches of V_a & V_b
  
  • Accompany vasculature
• Parasymp secretomotor: from PPG
  
  • Pregang to PPG by greater petrosal n. (VII)

Question 17

Describe the paranasal sinuses

Answer 17

• Series of membrane-lined cavities of facial bones
  
  • Ciliated mucous columnar epithelium
  • Currents directly spirally → openings
• For resonance (speech) & lighten the bones

Question 18

Describe the frontal sinus

Answer 18

Lies about the orbit, can be quite extensive

Question 19

Describe the maxillary sinus

Answer 19

• Large: occupies most of the maxilla
  
  • Lies lateral to nasal cavity

NB: opening above floor of sinus

Question 20

Describe the ethmoidal air sinuses

Answer 20

• Small, interconnected air cells between nose & orbit
• Middle sinus in the bulla of the ethmoid
• Hiatus semilunaris curved opening beneath bulla
  
  • Openings of frontal, maxillary & anterior ethmoidal

Question 21

Describe the sphenoidal sinus

Answer 21

• Opens in triangular space above superior concha
• Important relations:
  
  • Pituitary fossa superiorly
  • Cavernous sinus laterally

Question 22

Discuss anterior cranial fossa fracture

Answer 22

• Can cause CSF rhinorrhoea - drainage via nose
  
  • Leading to: purulent meningitis & anosmia

Question 23

Discuss sinusitis

Answer 23

• Inflammation of paranasal sinuses
• Symptoms:
  
  • Headache
  • Feeling of pressure in eyes, nose, cheeks
  • Cough
  • Fever
  • Halitosis
  • Nasal congestions with thick mucous

Question 24

Discuss maxillary sinusitis

Answer 24

• Causes pain/pressure in maxillary area
• May present with toothache

NB: Infection & damage more likely due to position of opening (drainage more difficult)

Question 25

Discuss the relevance of the location of the sphenoid sinus

Answer 25

* Transphenoidal hypophysectomy * Remove pituitary tumours confined to sella turcica/only extend to suprasellar region * Endoscope inserted through nose to sinus * Procedure of choice operation: significant advantages over open craniotomy