ENT Anatomy Flashcards
What forms the skeleton of the external nose?
Nasal bones forming the bridge of the nose, articulating with frontal bone above and frontal process of maxilla laterally. Lateral, septal and alar cartilages form the rest of the anterior projection.

What do the septal cartilages do?
Project into nasal cavity, separating it into two halves.

What comprises the lateral wall of the nasal cavity?
Maxilla
Palatine
Sphenoid
Ethmoid
Lacrimal
Inferior concha

What comprises the medial wall of the nasal cavity?
Maxilla, nasal bone, frontal, ethmoid, septal cartilage and vomer.

What sits at the front and back of the nasal cavity?
Anterior and posterior nares.

What is the structure of the ethmoid bone?
One horizontal plate in anterior cranial fossa by cribriform plate and downwards projections making the medial wall/septum and two lateral walls.

What can happen in a bad fracture of the ethmoid bone?
Can injure the cribriform plate and potentially allow infections in, bleeds into the meninges or produce subdural haemorrhages or rhinorrhoea, which is leakage of CSF from the subarachnoid space out into the nasal cavity.

What is the medial wall of the nasal cavity lined by?
Almost entirely by highly vascular mucous membrane.
What is the function of the mucous membrane of the nasal cavity?
Helps warm and humidify air before it enters lower airways
Helps prevent spasms of small muscles around bronchioles
Mucous partly humidifies but also traps foreign particles, prevents them entering the lower airways.
What is the nasal vestibule lined by?
Skin and hair - no vascular mucous membrane.

What is within the upper one third of the medial and lateral nasal walls?
Olfactory epithelium containing primary afferent olfactory neurons projecting up into the cribriform plate into the olfactory bulb.

What is within the lower two-thirds of the medial and lateral nasal walls?
Respiratory (pseudostratified squamous) epithelium that is ciliated, beating to encourage mucus towards the oral or nasal cavity.
What are the conchae?
Turbinate bones projecting off the lateral nasal wall into the nasal cavity - superior, middle and inferior.

What lines the conchae?
Highly vascular mucosa

What are the meatus?
The space between the conchae and the lateral wall or the concha above and the below.

What exists within the meatus?
Openings of sinuses into nasal cavity

What are the paranasal sinuses?
Frontal, ethmoid, sphenoid and maxillary sinuses.

How do the paranasal sinuses develop?
As outpouchings of the nasal cavity, dragging mucosa along with it, hence they too are lined by mucosa.

Why is drainage of the maxillary sinus difficult?
Because it, unlike the other sinuses, drains superior.

Which nerves innervate the paranasal sinuses?
CNV1: Frontal, ethmoid and sphenoid sinuses
CNV2: Maxillary sinus

Where does the nasolacrimal duct open?
Into inferior meatus

What does the nasolacrimal duct do?
Drains tear fluid produced in lacrimal gland in superolateral part of orbit.

What supplies blood to the superior quadrant of the nasal cavity?
Anterior and posterior ethmoidal arteries.

What supplies blood to the inferior quadrant of the nasal cavity?
Branches of greater palatine arteries that come in through the mouth and into the nose through a hole in the floor of the nasal cavity.











































































