Anatomy/Physiology of Nose & Sinus Flashcards
What is the function of the nasal airway?
- Warms and humidifies inhaled air
* Important for neonate - obligate nasal breather, choanal atresia
What is obligate nasal breathing in children?
Breathing through their nose rather than mouth
What is choanal atresia?
Congenital disorder where the back of the nasal passage (choana) is blocked causing breathing difficulties
How does the nasal airway warm and humidify inhaled air?
- Turbinate + septum - laminar flow
* Mucosal lining - humidification and contains sinuses which acts a reservoir of warm humid air
What is the function of the nasal?
- Nasal airway
- Immune barrier
- Smell
- Drainage and aeration of middle ear
- Drainage of paranasal sinuses and lacrimal duct
What nasal structures are important for smell?
• Olfactory nerve
Through cribriform plate
• Olfactory mucosa
What is the name of the tube involved in drainage and aeration of middle ear?
Eustacian tube
What are 5 function of the sinus?
- Reservoir of warm humid air
- Lighten skull
- Crumple zones
- Vocal resonance
- Line with same mucosa - immune barrier
What are the different sections to the external nasal anatomy?
- Lower and upper laterals
- Nasal septum
- External subunits
How much of the external nasal anatomy is bony and cartilaginous?
1/3 bony and 2/3 cartilaginous
What are the different parts to the external nose?
- Columella
- Tip + supra tip
- Dorsum
- Nasion
- Glabella
Why is it important to know the external nasal anatomy?
For nasal trauma:
• Broken bone: move back before they heal
• Broken/bent cartilage: hard to unbend
What are the structures of the internal nose?
- Midline - septum
- Roof: skull base/cribriform plate
- Walls: turbinates
- Floor: hard plate
Name four additional structures found in the internal nose
- Paranasal sinuses
- Orbits - lamina papyracea
- Eustacian tube
- Adenoids
What are the parts to the septum?
• Septal cartilage
• Vomer
Perpendicular plate of ethmoid
Describe the blood supply of the septum
- Poor blood supply
- Gets blood supply from mucosa overlying it
- Relevant in septal haematoma
What is a septal haematoma?
When blood collects in the septum of your nose
How does a septal haematoma form?
- Post trauma
- Usually bilateral
- Disruption of blood supply to septum -> septum necroses
- Leads to perforation - bleeding - must be drained ASAP
• Drugs and digital trauma
What are turbinates?
Bony scroll-like structure from lateral wall of nose
• Superior
• Middle
• Inferior
What is the function of turbinates?
Increases surface area of the nose for humidification and warming
What covers the turbinate and what is its function?
Erectile tissue - swells in response to tissue
What ducts open underneath the turbinates?
Sinuses and nasolacrimal
What is the function of the nasolacrimal duct?
Drainage pathway of lacrimal sections (tears) from the lacrimal sac (medial to eye) to under inferior turbinate into the inferior meatus
Causes runny nose when crying
Where are the paranasal sinuses located?
- 2 Frontal
- 2 Maxillary
- Sphenoid
- Ethmoid air cells - anterior and posterior
Where do the frontal sinus drain to?
Drains into frontal recess behind eyebrows into the middle meatus (lateral to middle turbinate)
Site of Potts puffy (tumour of frontal bone) - complication of acute sinusitis
Describe structure of the ethmoid
- Honeycomb structure between eyes
- Anterior and posterior
- Middle turbinate turns at the back of the nose to attach to the lateral nasal wall - ground lamella
Where does the ethmoid drain to?
Ground lamella separate anterior and poster ethmoid sinuses
• Anterior ethmoids - drains into middle meatus
• Posterior ethmoids - drains into superior meatus (lateral to superior turbinate)
What is the lamina papyracea?
Paper thin bone between the ethmoids and orbit
What is the clinical relevance of lamina papyracea?
Any infection (i.e. sinusitis of ethmoid air spaces) can spread to the orbit and cause periorbital/orbital cellulitis
Wont improve until sinusitis treated
How does the sphenoid sinus drain?
Via sphenoethmoidal recess
What are anatomical relation to the sphenoid sinus?
- Optic nerve runs above
- Internal carotids either side
- Pituitary posterior
How does the maxillary sinus drain?
From behind each cheek and drains via the middle meatus
Site of facial pain
What arteries supply blood to the nose?
Internal and external carotid arteries
What two branches does the external carotid artery give off?
Maxillary and superficial temporal artery
What branches of the ECA supply the nose?
- Via maxilary: sphenopalatine and greater palatine
* Via facial: superior labial
What branches of the ICA supply the nose?
Via opthalmic artery: anterior and posterior ethmoid artery
What is the Little’s Area of the nose?
A region in the anteroinferior part of the nasal septum where four arteries anastomose to form a vascular plexus (Kiesselbach’s plexus)
What is the clinical significance of Little’s Area?
Most common site for nose bleeding
Pinch soft part of the nose for epistaxis (nosebleed), not the bony part
What is the main nerve that provides nasal innervation?
Trigeminal nerve (CN V):
• V1 Ophthalmic
• V2 Maxillary
What nerve provides sensation to the nose?
Vidian nerve (parasympathetic)
What is the clinical significance of the Vidian nerve?
Can cause vasomotor rhinitis and crocodile tears which are treated by a Vivian neuronectomy
What structures lie in the post-nasal space?
- Adenois
- Eustacian tube opening
- Soft palate muscles (attach to Eustachian tube)
- If middle ear problems, think back of nose
- Fossa of Rosenmuller
What is fossa of rosenmuller?
A bilateral projection of the nasopharynx just below the skull base
• Node of rouvier
• Nasopharyngeal carcinoma