Nasal Cavity Flashcards
What should you not use near nasal cartilages and why?
Do not use adrenaline containing LA near nasal cartilages as nasal cartilage does not have a direct blood supply, relying on diffusion from surrounding arteries, and since adrenaline is a vasoconstrictor, it can constrict arteries supplying cartilage to a point where nasal cartilage can die.
Name the bones of the nasal cavity:
What are the external boundaries of the nasal cavity?
- nasal bones
- ethmoid: forms part of nasal septum (perpendicular plate)
- middle and superior conchae are extensions of the ethmoid
- inferior nasal conchae: bones in their own right
- vomer: completes nasal septum
Superiorly: nasal bones
Inferiorly and laterally: maxillae
Draw onto the diagram Le Fort Fracture lines:
Which of these pose increased danger and why?
Le Fort II and III level fractures can disrupt cribriform plate, therefore a danger od infection spreading fromnasal cavity and paranasal sinuses into the anterior cranial fossa
Name the bones of the lateral wall:
Medial wall (nasal septum):
Lateral:
- superior/middle conchae
- maxilla (inferiorly and anteriorly)
- palatine bone (posteriorly)
Medial:
- perpendicular plate of ethmoid bone
- vomer
- septal (hyaline) cartilage
What issue can a septal haematoma pose?
A septal haematoma must be incosed and drained to prevent avascular necrosis of the spetal hyaline cartilage which depends on diffusion of nutrients from its attached nasal mucosa
Label the types of epithelium
- Keratinised stratified squamous epithelium: thick, protective
- Respiratory epithelium
- Olfactory mucosa: receives olfactory receptor cells (smell)
Explain the path of the olfactory nerve:
Receptor cells in olfactory mucosa:
- 1st neurones in chain, pass signals from olfactory mucosa, through cribrifirm plate and synapse in olfactory bulb
From olfactory bulb, 2nd neurones pass along the olfactory tract and ends in temporal lobe
- passed to higher centres
What is the somatic sensory nerve supply to the nasal cavity?
Antero-superiorly: opthalmic branch of trigeminal (CN V1)
Posteroinferiorly: maxillary branch of trigeminal (CN V2)
Split from tip of nose, back towards body of sphenoid
Briefly explain the blood supply of the nasal cavity:
Dual blood supply, originating from both external and internal carotid arteries
External: facial and maxillary
Internal: opthalmic
How does the opthalmic artery contribute to blood supply of nasal cavity?
Maxillary artery?
Facial artery?
Opthalmic artery:
- branches into anterior and posterior ethmoidal arteries
- supplies superior aspect of lateral and medial wall
Maxillary artery:
- gives of sphenopalatine and greater palatine arteries
- supplies posterior aspect and lower nasal mucosa
Facial:
- via lateral nasal branch or septal branch of superior labial artery
- supplies anterior nasal mucosa
What is Kiesselbach’s (Little’s) area?
- an arterial anastomosis on the nasal septum
- a common site of epistaxis (nosebleeds)
What are paranasal sinuses?
Name the 4 pairs:
What are they lined by? What does the lining secrete?
- air-filled spaces
Frontal sinuses, separated by a bony septum
Maxillary sinuses, aka antra
Ethmoidal air cells
Sphenoidal sinuses
- lined by mucous-secreting respiratory mucosa
- mucous drains into nasal cavities via ostia in the lateral walls of the nasal cavities
Where do the following structures drain:
- sphenoidal sinus
- ethmoidal air cells
- frontal sinus
- maxillary sinus
What is interesting about maxillary sinus?
- sphenoidal sinus: drains into sphenoethmoidal recess
- ethmoidal air cells: drain into superior and middle conchae
- frontal sinus: middle meatus
- maxillary sinus: middle meatus, drainage channel sits high up within sinus, so when istting upright, the mucous will stay in bottom of sinus
Why can the nose run when you cry?
- lacrimal gland produces ‘tears’ which wash over eye
- normally drains into lacrimal sac, which drains into nasolacrimal duct which drains into inferior meatus of nasal cavity
What is sinusitis?
What causes it?
- inflammation of mucosa of paranasal sinuses
- can affect 1 or more sinuses
- acute (once)/sub-chronic/chronic (recurring)
Causes include: infection, allergy, autoimmune issues
- cilia of respiratory tract waft mucous towards ostia
- viral upper resp. tract infection can cause swelling of mucosa, reducing diameter of ostia
- sinuses can become filled with infected mucous
Why is maxillary sinusitis common?
- large sinuses
- ostia being located superiorly in the medial wall of sinus compared to floor
- mucous has to drain against gravity
List some functions of the nasal cavities:
- convey respiratory gases between atmosphere and nasopharynx
- special sense of smell (olfactory area)
- ostia: allow drainage of mucous from paranasal sinuses
