The Nasal and Oral Cavities Flashcards
What separates the left and right nasal cavities from each other?
from the oral cavity inferiorly?
from the brain superiorly?
Thin, midline septum formed of cartilage and bone
Hard palate (the floor of the nasal cavity)
Bone - cribriform plate (the roof of the nasal cavity)
What lies posterior to the nasal cavity?
The nasopharynx
Also paranasal sinuses
Describe composition of midline nasal septum
Anteriorly- formed of cartilage
Posteriorly- formed of 2 thin plates of bone: superiorly the perpendicular plate of the ethmoid bone, inferiorly the vomer
Describe the lateral wall of the nasal cavity
3 projections of bone (superior, middle, inferior) - conchae or turbinates
Spaces inferior to them are meatuses (superior, middle, inferior)
Air travelling through meatuses is warmed, humidified and filtered
What happens to air as it travels through the meatuses?
It is warmed, humidified and filtered
Describe the anatomy of the cribriform plate
Separates nasal cavity from cranium and brain
Delicate section of bone, perforated with holes
Mucosa in upper part of nasal cavity contain olfactory receptors. The axons of these nerves travel through the perforations to the brain.
Describe blood supply to the nasal cavity
Several arteries, including branches of maxillary artery (a terminal branch of external carotid)
An anastomotic network supplies nasal septum, often site of bleeding in epistaxis
Sensory innervation of nasal cavity?
Branches of the trigeminal nerve (CN V)
Name CN V
Trigeminal nerve
What are the 4 sinuses?
Frontal, ethmoid, sphenoid, maxillary
Where are the frontal sinuses?
Where do they drain?
Anterior part of the frontal bone (forehead ones)
Drains into middle meatus
Where are the ethmoid air cells/sinuses?
Where do they drain?
They are air cells that lie within the ethmoid bone
posterior to frontal sinuses, anterior to sphenoid sinuses
(superior to the nasal cavity and medial to the orbits)
Drains into superior and middle meatus
Where are the sphenoid sinuses?
Where do they drain into?
The sphenoid bone
Most posterior sinus, posterior to ethmoid sinuses
Drain into spheno-ethmoidal recess (above superior turbiculate)
Where are the maxillary sinuses?
Where do they drain into?
The maxillae of the facial skeleton. (pyramidal cheek sinuses)
They lie lateral to the lateral walls of the nasal cavity
Drain into middle meatus - lies superomedially - cant drain fully when head is upright
The nasal cavity receives the nasolacrimal duct. What is it?
It drains the fluid that lubricates the anterior surface of the eye.
Opens into inferior meatus
Why we get a runny nose when we cry
What gives us a runny nose when we cry?
Nasolacrimal duct
How does the nasal cavity communicate with the middle ear?
Eustachian tube - auditory tube - connects middle ear to nasopharynx
Opening seen on lateral wall of nasopharynx surrounded by bulge of tonsillar tissue
What is the middle ear?
Small cavity in the temporal bone
Modified for hearing - 3 tiny bones that transmit sound waves to inner ear
Allows air to pass into middle air for equal air pressure either side of the tympanic membrane (between middle and external ear)
Describe the palate
Anterior - bone - hard palate
Posterior - muscle - soft palate
Palate is the roof of the oral cavity
What forms the hard palate?
Palatine process of maxillae
Horizontal plates of palatine bones
Function of the hard palate?
Prevents food/fluid entering nasal cavity
Tongue pushes up against is in 1st phase of swallowing - forces food/fluid backwards into oropharynx
Tongue pushes up against hard palate to articulate certain sounds