Nose Anatomy Flashcards
What do you call the area between the root and apex of the nose?
Dorsum
What is the significance of the ethmoid bone?
contributes to nasal cavities
What are the roof, lateral wall and septum formed by?
Roof - cribriform plate and crista Galli Lateral - superior and middle conchae, ethmoidal air cells, orbital plate of the ethmoid and inferior conchae Septum - perpendicular plate of ethmoid bone and vomer
Which level of le Fort fracture can disrupt the ethmoid bone?
2 and 3 as these fracture at the cribriform plate of the ethmoid
What is the danger of le fort fractures 2 and 3?
danger of infection spreading from the nasal cavity and paranasal sinuses into the anterior cranial fossa
What forms the lateral wall of the nasal cavity?
Superior and middle concha, inferior concha (one individual bone),, ethmoidal air cells and orbital plate of ethmoid bone. The maxilla and palatine bone also contribute along with the nasal bone
What is the septum made from?
Perpendicular plate of ethmoid bone and vomer plus septal hyaline cartilage
What is a feature of hyaline cartilage?
Avascular
What is the type of mucosa at each of the 3 locations?
- Keratinised stratified epithelium
- respiratory epithelium
- olfactory epithelium
What are the features of keratinised stratified squamous epithelium?
It is found at the apex of the internal aspect of the nose and contains small hairs that filer foreign objects. it is considered to be a ‘skin-like’ mucosa.
What are the features of respiratory epithelium?
Cilliated and produced mucous this is in order to trap and move foreign bodies to be swallowed and to humidify and warm air
What are the features of olfactory epithelium?
Contain nerve fibres from the olfactory nerve which sense smell.
What do you know about the olfactory nerve?
It is CN 1.
It is a special sensory nerve
It’s first neurons are in the olfactory mucosa (called receptor cells) and hang down through the cribiform plate. These detect smell. The signal then travels to the olfactory bulb (which is a ganglion containing the 2nd neurons and this is where synapses occur). The signal then continues down the optic tract to the temporal lobe.
Are olfactpry receptor cells present on just the lateral wall of the nose?
No, they are present on both the medial and lateral walls
What is the somatosensory supply to the nose?
The anterosuperior aspect is supplied by the opthalmic branch of the trigeminal nerve (CNV1)
The posteroinferior aspect is supplied by the maxillary division of the trigeminal nerve (CNV2)
present on both lateral wall and septum.
What are the branches of the external and internal arteries that supply the nose?
External - facial and maxillary
Internal - opthalmic
Which arteries give rise to the labelled arteries in the diagram?
Anterior and posterior ethmoidal - opthalmic
Sphenopalantine and greater palantine - maxillary
Lateral (or septal) - facial
What is Kiesselbach’s area?
What is its clinical significance?
This is the site of anastamoses between the anterior and posterior ethmoidal, sphenopalantine, greater palantine and lateral arteries.
This is the most common site for epitaxis (nose bleeds)
What are conchae and what are their functions?
There are 3 conchae (superior, middle and inferior) and can be called the turbinate bones. They are all covered in respiratory epithelium (so increase surface area for humidifying, warming and trapping bacteria) but also create turbulent air flow (which leads to better gas exchange).
What are meatuses?
How many are there?
These are the spaces behind the conchae and are where the paranasal sinuses drain to.
3 + 1 sphenoethmoidal recess which sits posterior to the superior concha
How would you ensure a nasogastric tube has made it to the stomach?
Taking an x-ray to below the diaphargm. The tube should stay midline until the level of the diaphragm, should not be coiled and the tip should be clearly visible. If measured the tip should be about 10cm from the GOJ.
What are the paranasal sinuses?
These are air filled spaces within the bones surrounding the nasal cavity.
How many paransal sinuses are present in the skull?
Ethmoid bone - many ethmoid air cells
Frontal bone - should have 2 (right and left separated by a septum)
Maxilla - 2
Sphenoid bone - 2
What lines the paranasal sinuses?
Respiratory mucosa (cilliated and mucous secreting)
What is the function of paranasal sinuses?
This is still debated but theories include:
- making the skull lighter as decrease the amount of dense bone in the skull
- Help with voice resonance
- Filters foreign bodies
Where does mucous secreted from the paranasal sinuses drain into?
Drains through the ostia in the lateral walls of the nasal cavities. These then drain into meatuses (spaces below the concha)
Where does each parasinuse drain to specifcally?
Superior meatus - Ethoidal air cells
Middle Meatus - ethmoidal air cells, frontal sinus, maxillary meatus
Sphenoethmoidal recess - sphenoid sinuses
What drains to the inferior meatus?
The nasolacrimal duct - this is why when you cry you get a runny nose!
What is sinusitis?
This is the inflammation of the mucosa of the paranasal sinuses cause by infection, allergy or autoimmune issues.
Which nerve senses pain from sinusitis?
CNV1 and CNV2
(can present as referred pain to the tooth as shared common nerve supply)
Why are the maxillary sinuses predisposed to sinusitis?
This is because in order for the sinus to drain the mucous must move against gravity as the ostia is located superiorly to the sinus (at the middle meatus).
It is also in close proximity to the teeth so an abscess that moves through the bone (causing a fistula) can cause infection.
Why is there referred pain to the teeth in sinusitis?
As there is a common sensory supply through the trigeminal nerve.
