Nose & Sinus Anatomy and Physiology Flashcards
Function of nasal airway?
- Warm and humidify inhaled air
- Turbinates and septum
- Laminar flow
- Mucosal lining
- Humidification
- Sinuses are a reservoir of warm humid air
- Turbinates and septum
- Important for neonates
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
- First 1/3 stratified squamous epithelium
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
What are some functions of sinuses?
- Reservoir of warm humid air
- Lighten skull
- Crumple zones
- Vocal resonance
- Lined with same mucosa (immune barrier)
What are some of the external subunits of the nose?
- Columella
- Tip and supratip
- Dorsum
- Nasion
- Glabella
What are examples of common nasal trauma?
- Broken bones
- Move back before they heal
- Broken/bent cartilage
- Cannot be easily unbent
What fors the following of the nasal passage:
- roof
- walls
- floor
Roof:
- Skullbase/cribiform plate
Walls:
- Turbinates
Floor:
- Hard palate
What are some internal nasal associated structures?
- Paranasal sinuses
- Orbits
- Lamina papyracea
- Eustachian tube
- Adenoids
What is the midline of the nose?
Septum
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
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 are 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
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?
- Drains into frontal recess
- Drains via middle meatus
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 sinusitis?
Sinusitis = inflammation of the sinuses
Sinusitis - aetiology
Can be due to allergies or infection
Sinusitis - complications
Normally self limiting (acute being less than 12 weeks)
Occasionally is chronic:
- Inflammation blocks sinus drainage
- Mucus in sinus gets infected causing more inflammation
- Can lead to polys causing further blockage
Sinusitis - treatment
- Medical management
- Remove allergic triggers, with or without antihistamines
- Treat infection
- Reduce inflammation
- Steroids (long term nasal spray)
- Surgery
- Remove polyps
- Open up sinus drainage pathways
- Risks
- Damage lamina papyracea (orbital damage)
- Damage to skull base (cerebrospinal fluid leak and meningitis)
What are risks of surgery for sinusitis?
- Damage lamina papyracea (orbital damage)
- Damage to skull base (cerebrospinal fluid leak and meningitis)
Where does the nose receive blood supply from?
Has excellent blood supply from internal and external carotid
External:
- Sphenopalatine artery (via maxillary)
- Also greater palatine (via maxillary) and superior labial (via facial)
Internal:
- Anterior and posterior ethmoidal artery (via ophthalmic)
Describe the nasal innervation of the nose?
Almost all trigeminal nerve (CN V):
- V1 ophthalmic
- V2 maxillary
Sensation is internal and external
What is found in the post-nasal space?
Adenoids:
- Waldeyers ring
Eustacian tube opening
Soft palate muscles attach to Eustachian tube to open it during swallow:
- Equalise middle ear
