9.1 Nose, Nasal Cavity And Paranasal Sinuses Flashcards
What are the functions of the nose/nasal cavity?
Olfaction
Filtering inspired air - trapping particles in nasal hair or mucous
Humidifying and warming inspired air
Drainage of secretions from paranasal sinuses and nasolacrimal ducts
Inspiration of air
Resonating chamber for speech
Describe the composition of the nose
Mainly cartilaginous
But also has a bony part: Frontal process of the maxillae and two nasal bones form its root
What can injuries to the nose cause?
Septal Haematomas
Septal deviations
Nasal bone fractures
Describe the structure of the nasal cavity
Extends from the anterior nasal apertures (nostrils) to the posterior nasal apertures (choanae). Opens into the nasopharynx.
Has a medial and lateral wall, roof and floor.
What forms the medial wall of the nasal cavity ?
The nasal septum
What does the nasal septum consist of?
perpendicular plate of the ethmoid bone
septal cartilage
vomer
Describe the pathology of a septal haematoma
Cartilaginous portion of the septum relies on the overlying perichondrium for its blood supply. Blood collects in space between perichondrium and cartilaginous septum. Perichondrium lifted off the cartilage.
Lack of blood supply and increasing pressure from accumulating blood causes ischaemia of cartilage. Irreversible necrosis of cartilage leading to saddle deformity.
How is a septal haematoma treated?
Blood between the perichondrium and cartilaginous septum drained.
Tamponade placed to keep perichondrium pressed to the cartilage, preventing reaccumulation of blood
Why is it important to inspect the nasal septum after any sort of nasal trauma?
Septal haematoma
What are the 4 major paranasal sinuses?
Maxillary
Frontal
Ethmoidal
Sphenoid
Which of the paranasal sinuses are not paired?
Sphenoid air sinus
What is the largest paranasal sinus?
Maxillary sinus
What makes up the ethmoidal sinuses?
Anterior, middle and posterior air cells
What are paranasal sinuses?
Air filled spaces within the skull lined with respiratory mucosa (ciliated pseudostratified columnar with goblet cells) . All communicate with the nasal cavity
How do most of the paranasal sinuses communicate with the nasal cavity?
Middle meatus
What can an obstruction of drainage of a paranasal sinus result in?
Accumulation of mucosal secretions
Development of infection
Acute sinusitis
What are the presenting symptoms of acute sinusitis?
Pain and tenderness over the sinus involved
Nasal discharge
General systemic upset (fever/feeling unwell)
What are the causes of acute sinusitis?
Infections of the nose (cold)
Dental infections
How do dental infections cause acute sinusitis?
the roots of some of the upper teeth lie in the floor of the maxillary sinus
What is sinusitis?
Sinusitis is an inflammation of the lining of the sinuses
How do upper respiratory tract infections cause sinusitis?
Mucosal oedema
Impedance of ciliary function
Increasing mucosal secretions
Cause obstruction of drainage and increased stagnant pooling of mucus in sinus.
What is the most commonly affected sinus in sinusitis?
Maxillary sinus
How is sinusitis diagnosed?
History and clinical examination alone
How is sinusitis treated?
Self limiting, simple analgesics, should improve within 1-2 weeks
Secondary bacterial infection may require antibiotics (suggested by prolonged, severe symptoms)
How might orbital cellulitis be a complication of sinusitis?
Ethmoidal sinusitis can break through thin medial wall of orbit.
Infection spreads into orbit causing orbital cellulitis
Why is orbital cellulitis a cause for concern?
Potentially sight threatening if optic nerve involved.
May track back to involve other intracranial structures.
What is the vestibule of the nose?
The prominent external nose
Describe the lining of the vestibule
Respiratory epithelium (ciliated pseudo-stratified columnar with goblet cells)
Sebaceous glands
Sweat glands
Hair
What is the floor of the nasal cavity?
Hard palate (roof of oral cavity)
How might nasal bone fractures present?
History of facial injury
Swelling of area around nose
Evidence of deviation of the nose
What is the medial wall of the nasal cavity?
Nasal septum
Describe the the structure of the lateral wall of the nasal cavity
3 bony projections (conchae/turbinates)
-superior, middle and inferior conchae
3 meatuses underneath each conchae
What structure forms the superior and middle conchae of the nasal cavity?
Ethmoid bone
What are the nasal meatuses?
Superior middle and inferior meatuses are spaces under the conchae of the lateral wall of the nasal cavity.
What is the function of the conchae and meatuses of the later wall of the nasal cavity?
To slow inspired air by creating turbulence of airflow through vestibule.
Increase surface area over with air passes.
Allows us to better warm, filter and humidify inspired air
What structures communicate into the meatuses of the lateral wall of the nasal cavity
Paranasal air sinuses (mostly communicate with the middle meatus
Nasolacrimal duct - tears drain into the nasal cavity (opens into inferior meatus)
What bones form the roof of the nasal cavity?
From anterior to posterior: Nasal bone Frontal bone Ethmoid bone Sphenoid bone
How do surgeons access the pituitary gland?
Transsphenoidal surgical approach
Endoscope enters through anterior nasal apertures into nasal cavity. Passed through sphenoid bone to access pituitary
What forms the posterior component of the nasal septum?
Perpendicular plate of ethmoid bone
Vomer bone
Where does blood accumulate in a septal haematoma?
Sub-perichondrium
What causes a saddle nose deformity?
Untreated septal haematoma leading to avascular necrosis of the cartilaginous septum
Which cranial nerve carries general sensation from the nasal cavity?
Trigeminal nerve
What nerve supplies general sensory to the nasal cavity?
Ophthalmic and maxillary division of the trigeminal nerve
What lines the olfactory region of the nasal cavity?
Specialised olfactory mucous membrane
- contains dendrites of olfactory nerves on roof of nasal cavity
Where are odours detected by the nose?
By dendrites of the olfactory nerves within the mucous membrane covering the olfactory region of the superior nasal cavity. Trigger action potentials related back to the brain.
What is the function of the respiratory mucous membrane in the nasal cavity?
- Filters (mucous/cilia)
- Humidifies (watery secretions)
- Warms (rich blood supply- very vascular)
How do nasal polyps present?
Fleshy, benign swellings of the nasal mucosa Usually bilateral Common in over 40 years Pale or yellow in appearance Usually occur within the meatuses
What are the symptoms of nasal polyps?
Blocked nose Watery rhinorrhoea Post-nasal drip Decreased smell and reduced taste Mouth breathing More prone to acute sinusitis (block drainage of sinuses into nasal cavity)
What symptoms would suggest a nasal tumour?
Unilateral polyp
Blood tinged secretion
What is rhinitis?
Inflammation of the nasal mucosal lining
What are the symptoms of rhinitis?
– Nasal congestion – Rhinorrhoea (“runny” nose) – Sneezing – Nasal irritation – Postnasal drip
What are common causes of rhinitis?
Simple acute infective rhinitis (viral)
Allergic rhinitis
What is epistaxis?
Nose bleed.
What provides the arterial supply to the nasal mucosa?
Branches from the ophthalmic artery (anterior ethmoid and posterior ethmoid artery)
Branches from the maxillary artery (Sphenopalatine and greater palatine artery )
Form rich anastomoses
What is Kiesselbach’s plexus?
Arterial anastomoses in the anterior septum
What is the most common source of bleeding in epistaxis?
Kiesselbach’s plexus
How is anterior epistaxis treated?
Pinching nose in front of nasal bone
What is the venous drainage of the nasal cavity?
Into pterygoid venous plexus in the infratemporal fossa (also drainage to cavernous Indus and facial vein)
What type of epistaxis are more difficult to treat?
Bleeds from the sphenopalatine artery (back of nasal cavity and difficult to treat, higher pressure of blood)
What is the functions of the paranasal air sinuses?
Humidify and warm inspired air
Reduce weight of skull
What are Ostia?
Small channels draining the paranasal air sinuses into the meatus of the nasal cavity
What important anatomical relation do the ethmoid air sinuses have?
Orbital cavity as in the medial wall of the orbit
What are the important anatomical relationships do the paranasal air sinuses have?
Nasal cavity
Orbit
Anterior cranial fossa
Roots of the upper teeth
What provides general sensory innervation to the paranasal sinuses?
Branches of the CN V
- Va (frontal, ethmoidal and sphenoid sinus)
- Vb (maxillary sinus)
What often causes acute sinusitis?
Viral infection of nasal cavity
How do we diagnose acute sinusitis?
clinical diagnosis based of history and examination
Recent URTI
Block nose and rhinorrhoea with yellow/green discharge
Pyrexia
Headache
Facial pain in area of infected sinus - worse of leaning forward
How is sinusitis treated?
Symptomatically (analgesia, antipyretic, steam inhalation)
What are the symptoms of an acute bacterial sinusitis?
Acute bacterial sinusitis more likely if
• Symptoms particularly severe at onset
• Symptoms >10 days without improvement (but <4 weeks)
• Symptoms that worsen after an initial
improvement (suggesting secondary
bacterial infection)
What are the commonest bacteria. That cause acute bacterial sinusitis?
Streptococcus pneumoniae
Haemophilus influenzae
Mortadella catarrhalis
