Lecture 13 - Nose and paranasal sinuses Flashcards
Functions of the nose
- Smell
- Route for inspired air
- Filters inspired air - raps particles in nasal hair and mucous
- Turbulent air flow
- Humidifies and moistens inspired air
- Resonating chamber for speech
Nasal cavity lining
Psuedostratified columnar cells with goblet cells
Vestibule
Anterior part of nose before conchae lined with skin containing sebaceous and sweat glands and nasal hair.
Filters inspire air
Boundaries of the nasal cavity
Roof - anterior crania fossa where the cribriform plate is
Floor - Hard palate
Lateral walls - conchae on ethmoid bone
Medial - nasal septum of the ethmoid bone and septal cartilage
Conchae
Bony projections on the lateral wall of the nasal cavity covered by respiratory mucosa
- Superior
- Middle
- Inferior
Meatuses
Gaps between conchae
- superior
- middle
- inferior
Runny nose
Nose runs due to tears running into the nasal cavity from the lacrimal ducts
Openings under the meatuses
Allow drainage of the paranasal air sinuses especially under the middle meatus
Drainage of nasolarimal duct into the nasal cavity
Septal haematoma
Septal cartilage is avascular and receives blood from the septal perichondrium
- Trauma can cause damage to the perichondrium
- Tear blood vessels
- Blood accumulates sub-perichondrium forming a septal haematoma
Saddle nose deformity
Untreated septal haematoma leads to avascular necrosis of septum cartilage
Get saddling of nasal dorsum
Complication of septal haemoatoma
Can get infection in the haematoma forming a septal abscess
Increasing chance of avascular necrosis
Innervation to nose and nasal cavity
General sensation - trigeminal nerve
Va - vestibule
Vb - conchae and nasopharynx
Olfactory mucous membrane
Contains olfactory receptor neurones - CN I
Respiratory mucous membrane
Psuedostratified columnar ciliated epithelium rinch in goblet cells
- Filters - mucous and cilia
- Humidifies - watery secretions
- Warms - vascular
Nasal polyp
Benign fleshy accumulation of respiratory mucosa
- Normally bilateral
- Commonly seen in under 40 yr olds
Symptoms:
- Decreased smell and taste
- Blocked nose and watery rhinorroea
- Yellow or pale lump in nasal cavity, felshy and reddened
- Post nasal drip
- Tickly cough as polyp drips into nasopharynx onto larynx
More concerning if unilateral or blood secretions as may be tumour
Rhinitis
Inflammation of the nasal mucosal lining
Causes:
- rhinorroea
- sneezing
- post-nasal dripping
- nasal congestion
- nasal irritation
Common causes of rhinitis
Simple acute infective rhinitis - viral e.g. common cold
Allergen e.g. pollen or house dust
Epitaxis
Nose bleed
Blood supply to nasal cavity
From opthalmic (ethmoidal) and maxillary artery (sphenopalatine and greater palatine)
Anastomose in anterior septum in Kiesselbach’s plexus
Venous drainage of nasal cavity
Pterygoid venous plexus
Cavernous sinus
Facial vein
Paranasal air sinuses
Air filled spaces that are extensions of the nasal cavity lines with respiratory mucosa - ciliated and secrete mucous
4 Paranasal air sinuses
Frontal
Ethmoidal
Sphenoid
Maxillary
Roleof paranasal air sinuses
- Warm and humidify inspired air
- Reduce weight of skull
Ostia
Small channels that allow the drainage of the paranasal air sinuses into a meatus of the nasal cavity
Sinusistis
Inflammation of the mucosal lining of the paranasal air sinuses and nasal cavity due to infection
Maxillary most commonly affected
Innervation of the paranasal air sinuses
Trigeminal nerve
Frontal, ethmoidal and sphenois - Va
Maxillary - Vb
Presentation of acute sinisitis
Blocked nose Rhinorrhoea Pyrexia Recent URTI Headache and facial pain
Pathophysiology of acute sinisitis
- Primary infection causes decreases cilia function, oedema of the mucosa and ostia and increased nasal secretions
- Drainage from sinus impeded
- Stagnant secretions in sinus - breeding ground for bacteria
Why is the maxillary sinus most commonly affected?
Drainage is higher up into the nasal cavity so needs to work against gravity
COmmon bacteria in acute sinistis
Strep pneumoniae
Haemophilus influenzae
Moraxella Catarrhalis
