Session 9 - The Nose Flashcards
What are the functions of the nose and nasal cavity?
Sense of smell Provides a route for inspired air Filters inspired air, trapping particle in nasal hair or mucous Moistens and warms inspired air Resonating chamber for speech
Inspired air enters the nasal cavity via what?
The vestibule
What is the vestibule lined by?
Skin
Hair
Sebaceous glands
Why are the nasal bones so common to fracture in facial injuries?
Because of the prominence of the nasal bones
How is the pituitary gland accessed during pituitary surgery?
Through the nose and then through the sphenoid bone (trans-sphenoidal)
What epithelium is found in the respiratory mucus membrane of the nasal cavity? How do the features of this epithelium allow the functions of the nasal cavity to be carried out?
Pseudostratified columnar ciliated epithelium:
- mucous/cilia - filters
- watery secretions - humidifies
- rich blood supply - warms inspired air
Other than the respiratory mucus membrane, what other sort of mucous membrane is present in the nasal cavity?
Olfactory mucous membrane
The mucous membranes in the nasal cavity receive drainage from where?
Paranasal sinus Nasolacrimal duct (drains eye)
What are the boundaries of the nasal cavity?
Floor - hard palate
Lateral wall - conchae and meatuses
Medial wall - nasal septum
Roof - frontal bone, cribriform plate (ethmoid bone), sphenoid bone
What are the three bony projections in the lateral wall of the nasal cavity called?
Superior concha
Middle concha
Inferior concha
Paranasal air sinuses and the nasolacrimal duct drain into what parts of the lateral wall of the nasal cavity?
Meatuses
What is the function of the nasal conchae?
Slows airflow by causing turbulence
Increases the surface area over which air passes
Where does the cartilaginous part of the nasal septum take its blood supply from?
The overlying perichondrium
Explain how a septal haematoma may occur.
Trauma to the nose can lead to buckling of the nasal septum and steering of blood vessels.
Blood accumulates between the cartilage and the perichondrium, creating a septal haematoma
If a septal haematoma is left untreated it may develop into what?
Saddle-nose deformity
Septal abscess
Why does a saddle deformity occur in untreated septal haematomas?
Untreated septal haematoma leads to avascular necrosis of the cartilaginous septum. This therefore leads to saddling of the nasal dorsum.
Formation of a septal abscess will further increase the likelihood of avascular necrosis of the septum.
Which cranial nerve carries general sensation from the nasal cavity?
Trigeminal (opthalmic and maxillary branches) (CN Va and Vb)
What are nasal polyps?
Benign swellings of the nasal mucosa
Describe the appearance of nasal polyps.
Swellings can either be pale or yellow in appearance, or may be fleshy and reddened.
What are the symptoms of nasal polyps?
Blocked nose
Watery rhinorrhoea
Post-nasal drip
Decreased smell and reduced taste
A unilateral nasal polyp with or without a blood tinged secretion is suggestive of what?
Tumour
What is rhinitis?
Inflammation of the nasal mucosal lining
What are the common causes of rhinitis?
The common cold (acute infective rhinitis)
Allergic rhinitis
What are the symptoms of rhinitis?
Nasal congestion Rhinorrhoea (‘runnuy’ nose) Sneezing Nasal irritation Postnasal drip
What is the most common sauce of bleeding in epistaxis?
Kiesselbach’s plexus
Arterial supply to the nasal cavity arises from branches of what two arteries?
Ophthalmic artery
Maxillary artery
What blood vessels does venous blood from the nasal cavity drain into?
Pterygoid venous plexus
Cavernous sinus
Facial vein
Epistaxis from what other artery is less common but potentially more serious and difficult to treat?
Sphenopalatine artery
What are paranasal sinuses?
Air filled spaces that are extensions of the nasal cavity. Named according to the bone in which they are found.
Paranasal sinuses are lined with what mucosa?
Respiratory mucosa (thus are also ciliated and secrete mucous)
What is the purpose of paranasal air sinuses?
Help to humidify and warm inspired air.
Reduce weight of the skull.
All paranasal sinuses drain into a meatus (mostly the middle meatus) via what channels?
Ostia
What is sinusitis?
Infection of a sinus
Which paranasal sinus is most commonly affected by sinusitis?
Maxillary
What are the 4 paranasal sinuses called?
Frontal sinus
Ethmoidal sinus
Sphenoid sinus
Maxillary sinus
Roots of the upper teeth can sometimes project into which paranasal sinus?
Maxillary
What is anther name for conchae?
Turbinates
Which branches of the trigeminal nerve provide general sensory innervation to the paranasal sinuses?
Frontal, ethmoidal, sphenoid - ophthalmic (CN Va)
Maxillary - maxillary (CN Vb)
Explain how rhinitis leads to sinusitis.
Primary infection (rhinitis) leads to reduced ciliary function, oedema of nasal mucosa and sinus ostia and increased nasal secretions. This impedes drainage from the sinus. Stagnant secretions within the sinus become an ideal breeding ground for bacteria, learning to the secondary infection (sinusitis).
What does the nasal septum consist of?
Perpendicular plate of the ethmoid bone
Septal cartilage
Vomer
How would acute sinusitis present?
Pain and tenderness over the sinus involved
Nasal discharge
General systemic upset (fever, feeling unwell)
What are the causes of sinusitis?
Infections of the nose (rhinitis, upper respiratory tract infections) Dental infections (roots of some upper teeth can lie in the floor of the maxillary sinus)
Give a rare complication of ethmoidal sinusitis.
Orbital cellulitis - this is potentially sight-threatening as could involve optic nerve or even track further back to involve intracranial structures.
Why is the maxillary sinus most commonly affected by sinusitis?
The maxillary sinus drains poorly because the ostium sits high up the wall of the sinus, meaning it has to drain upwards.
