The Nose Flashcards
What are the functions of the nasal cavity?
Conduit for air Filters air (vibrissae) Humidifies air (glands) Warms air (blood) Sense of smell
What are the structures of the external nose?
Root Dorsum Tip 2 Ala Septum 2 Nostrils
What are the bones of the nose?
Frontal bone Ethmoid bone Perpendicular plate of the ethmoid bone Nasal bone Maxilla Vomer Inferior nasal concha
Which parts of the nasal cavity does the ethmoid bone form?
Parts of the roof, lateral walls and septum
What are the components of the ethmoid bone?
Cribriform plate Crista galli Perpendicular plate Superior concha Middle concha Ethmoidal air cells
Which structures form the nasal septum?
Perpendicular plate of ethmoid bone
Septal cartilage
Vomer
Which structures form the lateral wall of the nasal cavity?
Superior concha Middle concha Inferior concha Lateral cartilage Right palatine bone Right maxilla
Which fractures can result in anosmia and why?
Le Fort II, III and Basillar skull fractures
Disruption of cribriform plate can sever olfactory nerves
Why might leakage of fluid from the nose be a sign of facial fracture?
Disruption of the paranasal sinuses
What is the histology of the nasal mucosa?
Nasal vestibule = stratified squamous epithelium (keratinised to non-keratinised)
Nasal cavity = respiratory epithelium
Superior concha = olfactory epithelium
What is the olfactory pathway?
Receptor cells in olfactory epithelium detect smell
Pass up through cribriform plate (olfactory nerves)
Synapse with olfactory bulb (ganglion)
Neurones pass along olfactory tract
Reach temporal lobe and olfactory areas
What is the somatic sensory innervation of the nasal cavity?
(Cavity divided by diagonal line from sphenoid sinus to tip of nose)
Above = Ophthalmic division of trigeminal (CNV1) branches to give anterior ethmoidal nerve
Below = Maxillary division of trigeminal (CNV2) branches to give nasopalatine nerve
Through which structure does the nasopalatine nerve enter the nasal cavity?
Sphenopalatine foramen
Through which structure does the anterior ethmoidal nerve enter the nasal cavity?
Anterior ethmoidal foramen
What is the blood supply to the nasal cavity and surrounding structures?
Internal carotid artery -> Ophthalmic artery -> anterior and posterior ethmoidal arteries
External carotid artery -> Maxillary artery -> sphenopalatie and greater palatine arteries
External carotid artery -> Facial artery -> superior labial artery, lateral nasal and septal branches
What is epistaxis?
Nose bleed
What is Kiesselbach’s Area and where is it found?
Sire where anastomoses occurs between arterial contributions
Located anteroinferiorly on nasal septum
What causes eptaxis?
Disruption to Kiesselbach’s Area
What is the order of the concha and their associated recess/meatuses?
Sphenoethmoidal recess Superior nasal concha Superior meatus Middle nasal concha Middle meatus Inferior nasal concha Inferior meatus
Why are conchae often referred to as turbinates?
Cause turbulent airflow through nasal cavity
Increased opportunity for humidifying, warming and filtering
What can impact the airflow through the nasal cavity?
Engorgement of the nasal mucosa
One side will be engorged then change to the other side every 1-5 hours
Due to erectile tissue (arteriovenous)
What are the four bilateral sinuses associated with the nasal cavity?
Frontal sinuses
Ethmoidal air cells
Maxillary sinuses
Sphenoid sinuses
What lines each sinus?
Thin respiratory epithelium
What is the drainage of the sphenoid sinus?
Sphenoethmoidal recess
What is the drainage of the ethmoidal air cells?
Posterior = superior meatus Middle = ethmoidal bulla (middle meatus) Anterior = semilunar hiatus (middle meatus)
What is the drainage of the frontal sinus?
Semilunar hiatus (middle meatus)
What is the drainage of the axillary sinus?
Semilunar hiatus (middle meatus)
What is the pathway of lacrimal fluid drainage?
Lacrimal gland, lacrimal sac, inferomedially to nasolacrimal duct, inferior meatus
What is sinusitis?
Inflammation of the mucosa in 1 or more of the paranasal sinuses
How does sinusitis occur?
Cilia of respiratory mucosa waft mucous toward ostia
Viral URTI causes swelling of mucosa, reducing diameter of ostia
Sinuses become filled with infected mucous and pressure builds
Why is pain felt in sinusitis?
Sensation provided by CNV1 and CNV2
May be referred to the teeth
Which sinus is predisposed to infection and why?
Maxillary
Ostium is located superior to cavity - cilia must work against gravity
