Nasal Anatomy and Physiology Flashcards
what is the function of the nasal airway?
humidify and warm inspired air
Remove noxious particles from the air, protects delicate distal lower respiratory tract
what does a blocked nose typically cause?
dry mouth disturbed sleep
what do tracheostomy/laryngectomy patients require?
humidifiers
why is the nose important for olfaction?
Sense organ, housing the olfactory apparatus
Smell substances for pleasure and defence purposes.
Important role in protection from danger, such as fire
Central in forming positive and negative memories
Taste: While chewing, chemicals from food activate olfactory receptors to identify food flavour.
Dysfunction can result poor quality of life
what is choanal atresia?
Choanal atresia is a congenital disorder in which the nasal choanae, (i.e., paired openings that connect the nasal cavity with the nasopharynx), are occluded by soft tissue (membranous), bone, or a combination of both, due to failed recanalization of the nasal fossae during fetal development.
Neonates are obligate nasal breathers
This is an emergency, as neonate will be unable to breathe
Requires surgical repair
what are the four funtions of the nose?
immune
speech
nasal airway
olfaction
what is the immune function of the nose?
Mucus consists of compounds that are able to neutralize antigens
Immunoglobulin A (IgA) and immunoglobulin E (IgE)
Good example is nasal flu vaccine
Smoking reduces number of cilia and change in mucous viscosity.
what are the speech functions of the nose
Nasal airflow modifies speech and produce nasal clicks or click consonants.
Paranasal sinuses also contribute to vocal resonance.
People with blocked nose sound ‘bunged up’
How is the nasal airway able to act as immune barrier?
Specialised nasal mucosal lining
First 1/3 stratified squamous epithelium
Nasal hairs trap large particulates
Posterior 2/3 pseudostratified columnar epithelium
Cilia allows mucus to travel 2.5cm/min
Goblet create sticky mucus that trap pathogens
Mucus contains IgA, IgE (allergies), lysozymes, alkaline
What is the structure of the nasal epithelium?
First 1/3 stratified squamous epithelium
Nasal hairs trap large particulates
Posterior 2/3 pseudostratified columnar epithelium
Cilia allows mucus to travel 2.5cm/min
Goblet create sticky mucus that trap pathogens
Mucus contains IgA, IgE (allergies), lysozymes, alkaline
What does mucus contain?
Mucus contains IgA, IgE (allergies), lysozymes, alkaline
Through what does smell occur?
Olfactory nerve
Through cribrifom plate
Olfactory mucosa
What allows drainage and aeration of middle ear?
Drainage and aeration of middle ear:
Eustachian tube
how is nasal air flow described?
laminar as it enters the nasal vestibule
how does velocity of air change as it travels through nasal valve?
Velocity of the air increases through the nasal valve, the narrowest site of the upper respiratory tract.
what is the function of the paranasal sinuses?
Thye are air filled and arise from the nasal cavity
Reduce skull weight
Physical buffer / crumple zone
Vocal resonance
Humidification
Heat insulation
Immune barrier
What are some of the external subunits of the nose?
Columella
Tip and supratip
Dorsum
Nasion
Glabella
how would you descibe the shape of the external nose?
Visible component of face
Pyramidal shape, with base continuous with forehead and apex at the nasal tip.
what is the dorsum of the nose?
surface between root of nose and tip.
what are the openings of the nose?
nares
what are the nares separated by?
columella
what different components does the nasal skeleton have?
Bony and cartilaginous components
what are the nasal bones?
The internal nasal septum separates the nasal cavity into two nostrils.
The bones that contribute to the nasal septum can be divided into: Paired bones: Nasal, maxillary and palatine bones. Unpaired bones: Ethmoid and vomer bones.
what are the nasal paired bones?
Nasal, maxillary and palatine bones
what are the nasal unpaired bones?
Ethmoid and vomer bones.
what are the two main paired lateral cartilages of the nose?
Upper lateral cartilages
Lower lateral (alar) cartilages
what are the main cartilaes of the nose accompanied by?
Supported by septal cartilage
Smaller minor cartilages
What is the septum formed from?
Bone and cartilage:
Septal cartilage
Vomer
Perpendicular plate of ethmoid
Where does nasal cartilage get blood supply from?
Poor blood supply
Gets blood supply from mucosa overlying it
Relevant in septal haematoma
what is a nasal bone fracture?
Most common facial fracture
Can result in permanent deformity
Possible to correct before bone heals
how is a nasal bone fracture corrected?
Closed reduction of nasal fractures can be performed under local anesthesia in the majority of patients
complication - septal haematoma
What are examples of common nasal trauma?
Broken bones
Move back before they heal
Broken/bent cartilage
Cannot be easily unbent
Septal haematoma - pathology
Septal haematoma = blood collects in the septum
Septal haematoma - aetiology
Post trauma
Septal haematoma - presentation
Almost always bilateral
No blood supply to septum
Causes septum necrosis, leading to perforation so needs to be drained as soon as possible
what is a saddle nose deformity?
Saddle nose deformity refers to a collapsed nasal bridge, which causes the middle portion of your nose to sag
Cartilage has no blood supply of its own
Relies on surrounding perichondrium
Haematoma results in ischaemia and necrosis of the septum
Support to the nose lost
where does the skin of the external nose receive its arterial supply from?
supratrochlear and dorsal nasal arteries (branches of the ophthalmic artery) and infraorbital artery (branch of maxillary artery).
where do the septum and alar cartilages receive their blood supply from
angular artery and lateral nasal artery
what are the angular artery and lateral nasal artery branches of?
Both are branches of the facial artery
where does the vessels from the external nose drain into?
facial vein
Where does nasal cartilage get blood supply from?
Poor blood supply
Gets blood supply from mucosa overlying it
Relevant in septal haematoma
what is the danger triangle of the face?
Highly anastomotic venous system of nose within danger triangle allows retrograde spread of infection to cavernous sinus via ophthalmic veins – life and sight threatening!
what may affect danger triangle and what may be signs of infection?
Can be relatively simple infection e.g. nasal furuncle
Ptosis, chemosis, cranial nerve palsies (III, IV, V, VI).
Sensory deficits of the ophthalmic and maxillary branches.
Papilloedema, retinal haemorrhages, decreased visual acuity and blindness may occur
Fever, tachycardia and sepsis may be present
Headache with nuchal rigidity (neck stiffness)
what is sensory innervation of the external nose derived from?
trigeminal nerve (CN V)
which nerves supply the skin of the dorsum of nose, nasal alae and nasal vestibule?
Infratrochlear and external nasal nerves, branches of the ophthalmic nerve (CN V1)
what nerve are the lateral aspects of the nose supplied by?
infraorbital nerve, a branch of the maxillary nerve (CN V2)
what is motor innervation ro rhe nasal muscles innervated by?
facial nerve (CN VII).
what makes up the nasal musculature?
Nasalis is a paired muscle that covers the dorsum of the nose. It consists of two parts; alar and transverse.
Procerus - small pyramidal muscle occupying the glabella
what is the nasalis innervated by?
Buccal branch of facial nerve (CN VII)
what action does the alar part of the nasalis have on the nose?
Depresses ala laterally, dilates nostrils
what action does the transverse part of the nasalis have on the nose?
Wrinkles skin of dorsum of nose
what is the procerus innervated by?
temporal, lower zygomatic or buccal branches of facial nerve (CN VII)
what action does the procerus have on the face?
depress the medial ends of the eyebrows, wrinkles skin over the glabella - creates a facial expression of frowning, or when exposed to bright light or other eye irritants.
what three parts is the internal nose/nasal cavity divided into?
Vestibule – entrance to cavity, lined hair bearing skin
Respiratory region - lined by a ciliated psudeostratified epithelium, with mucus-secreting goblet cells.
Olfactory region - at the apex of the nasal cavity. It is lined by olfactory cells with olfactory receptors.
describe the vestibule?
entrance to cavity, lined hair bearing skin
describe the respiratory region?
lined by a ciliated psudeostratified epithelium, with mucus-secreting goblet cells.
describe the olfactory region?
at the apex of the nasal cavity. It is lined by olfactory cells with olfactory receptors.
what is the nasal septum?
Vertical wall, divides left and right nasal passages.
Forms medial wall of nasal passage
Consist of bony and cartilaginous parts
what bony and cartilaginous parts make up the nasal septum?
Quadrangular cartilage
Perpendicular plate of ethmoid
Vomer
Maxillary crest
Palatine bone
what are nasal turbinates?
Bony skull like projections from lateral wall of the nose:
Superior
Middle
Inferior
What is the function of turbinates?
Increases surface area of the nose:
Humidification and warming of air
What are turbinates covered in?
Covered in erectile tissue:
Day to day cycling
Respond to temperature
What opens underneath turbinates?
Sinuses and nasolacrimal duct open underneath turbinates:
Meatus
Correspond to turbinate they are under
What is the nasolacrimal duct?
Drainage pathway of lacrimal secretions (tears)
From lacrimal sac
Where does nasolacrimal duct open?
Opens under inferior turbinate
Inferior meatus
how would you descibe the vasculature of the internal nose?
Rich vascular supply –allows humidification and warming of inspired air.
Supply from both internal and external carotid arteries:
what are the internal carotid branches that supply the internal nose?
Anterior ethmoidal artery
Posterior ethmoidal artery
what are the external carotid branches that supply the internal nose?
Sphenopalatine artery
Greater palatine artery
Superior labial artery
Lateral nasal arteries
what is epistaxis?
Epistaxis (nosebleed) is one of the most common ear, nose, and throat (ENT) emergencies that present to the emergency room or primary care. There are two types of nosebleeds: anterior (more common), and posterior (less common, but more likely to require medical attention)
where is the most common site for epistaxis to occur?
Commonest site at Little’s area (Kiesselbach plexus) on anterior septum
is epistaxis easy to treat at littles area?
Easy to access and cauterise under local anaesthesia
where is posterior bleeding typically from?
Woodruff plexus - more likely to require nasal packing
can nasal packing be anterior and posterior?
Nasal packing can be anterior or posterior
Rapid rhino vs merocel
Foley catheter and ribbon gauze
what does surgical management of epistaxis include?
Surgical management includes endoscopic ligation of sphenopalatine artery
in the context of a nasal fracture what blood vessel is the most likely source?
In context of nasal fracture, anterior ethmoid likely source
Surgical management via external approach
What are the paranasal sinuses?
2 frontal
Behind eyebrows
Drains into frontal recess
Drains via middle meatus
Lateral to middle turbinate
2 maxillary
Behind each cheek
Drains via middle meatus
Sphenoid
Drains via the sphenoethmoidal recess
Optic nerve runs above it
Internal carotids either side
Pituitary is posterior
This is why severe sinusitis can cause neurological problems
Ethmoid air cells (anterior and posterior)
Honeycomb structure between eyes
Middle turbinate turns at the back of the nose to attach to the lateral nasal wall
This turn is called the ground lamella
Anterior to this is the anterior ethmoid which drains into the middle meatus
Posterior to this is the posterior ethmoids which drains into the superior meatus
Clinical relevance is that infections spreads to orbit causing periorbital/orbital cellulitis
Where are the frontal sinuses located?
Behind eyebrows
Lateral to middle turbinate
What do the frontal sinuses drain and drain via?
frontonasal duct into hiatus semilunaris, within the middle meatus of the nasal cavity
Where are the maxillary sinuses located?
Behind each cheek
What do the maxillary sinuses drain via?
Drains via middle meatus
What does the sphenoid sinus drain via?
Drains via the sphenoethmoidal recess
What structures are found around the sphenoid sinus?
Optic nerve runs above it
Internal carotids either side
Pituitary is posterior
This is why severe sinusitis can cause neurological problems
Where are the ethmoid air cells?
Honeycomb structure between eyes
What is the ground lamella?
Middle turbinate turns at the back of the nose to attach to the lateral nasal wall
This turn is called the ground lamella
Anterior to this is the anterior ethmoid which drains into the middle meatus
Posterior to this is the posterior ethmoids which drains into the superior meatus
What does the anterior and posterior ethmoid air cells drain via?
Anterior to this is the anterior ethmoid which drains into the middle meatus
Posterior to this is the posterior ethmoids which drains into the superior meatus
What is the clinical relevence of the ethmoid air cells anatomy?
Clinical relevance is that infections spreads to orbit causing periorbital/orbital cellulitis
What sinuses drain via the following:
middle meatus
superior meatus
sphenoethmoidal recess
inferior meatus
Frontal, anterior ethmoids and maxillary
Middle meatus
Posterior ethmoids
Superior meatus
Sphenoid
Sphenoethmoidal recess
Nasolacrimal duct
Inferior meatus
what is the frontal sinus sensation via?
Sensation via supraorbital nerve (branch of the ophthalmic nerve)
what is arteral supply of frontal sinuses via
anterior ethmoidal artery (a branch of the internal carotid)
what do sphenoid sinuses drain via?
spheno-ethmoidal recess, supero-posterior to the superior turbinate.
Innervated by the posterior ethmoidal
what are sphenoid sinuses innervated by?
posterior ethmoidal nerve (a branch of the ophthalmic nerve)
what is the arterial supply of the sphenoid sinuses
sphenopalatine (branch of maxillary) and posterior ethmoidal artery (ICA)
when is trans-sphenoidl surgery performed?
Most often for pituitary adenoma
Other central skull base tumours also possible
Avoids transcranial approach
Joint procedure with ENT (access & closure) and Neurosurgery (resection)
Close proximity to internal carotid artery
CSF leak requires repair
which sinus are the largest of the sinuses?
maxillary sinuses
what do the maxillary sinuses drain by?
Drain via ostia at hiatus semilunaris, underneath the frontal sinus opening
what are the maxillary sinuses innervated by?
Innervated by superior alveolar nerves and greater palatine nerve (branches of maxillary nerve)
what is the arterial supply of maxillary sinuses?
Arterial supply via branches of facial and maxillary arteries
describe the ethmoid sinuses?
2 ethmoidal sinuses/ group of air cells:
Anterior – Opens into the hiatus semilunaris (middle meatus) via ethmoid bulla
Posterior – Opens into the lateral wall of the superior meatus
Innervated by anterior and posterior ethmoidal branches of the nasociliary nerve (from ophthalmic nerve) and the maxillary nerve.
Arterial supply via anterior and posterior ethmoidal arteries
what is Orbital cellulitis
cute spread of infection from ethmoid or frontal sinuses
Differentiate from pre-septal cellulitis (different causes) by clinical signs:
Proptosis, chemosis
Ophthalmoplegia
Painful eye movements
Decreased visual acuity/ loss of colour vision (red first)
Requires IV antibiotics, nasal decongestants, CT scan +/- surgical drainage
what is sinus drainage via?
Sphenoid via spheno-ethmoidal recess
Posterior ethmoid via lateral wall of the superior meatus
Anterior ethmoid, frontal, and maxillary via ostiomeatal complex in middle meatus:
Narrow passageway, prone to blockage 🡪 sinusitis
Nasolacrimal duct opens into inferior meatus
what is sinusitis?
Inflammation of lining of sinuses
Acute (<3 months) – usually viral
Chronic (>3 months) – with our without polyposis
Nasal obstruction
Chronic nasal discharge
Affect on smell
Static mucus can get infected
what is post nasal space
area posterior to nasal choanae, extending down to soft palate
Contents:
Adenoids and tubal tonsils – lymphoid tissue, make up part of Waldayer’s ring
Eustachian tube opening
Enlarged adenoids or other post nasal space mass can obstruct eustachian tubes
Glue ear – may require adenoidectomy and insertion of grommets
Unilateral in adults may be sign of nasopharyngeal mass (Fossa of Rosenmuller)
