_____ are air-filled cavities located in the frontal, ethmoid, and sphenoid bones of the cranium, as well as the maxillae of the face
Paranasal sinuses communicate with the _____ cavity
List the functions of the paranasal cavitites
- Serve as resonating chamber for the voice
- Decrease weight of skull
- Warm and moisturize inhaled air
- Act as shock absorbers in trauma
- Possibly control the immune system
____ sinuses are usually the only ones developed enough to be demonstrated radiographically at birth
_____ is the largest and most symmetric sinus
pyramidal in shape
____ is the second largest sinus
True or false: frontal sinuses are always symmetric?
False = rarely
____ sinus is located below sella turcica and extend between dorsum and posterior ethmoids
Where are the ethmoid sinuses located at?
within lateral masses of labryinths
Ethmoid sinuses are composed of varying number of air cells that are divided into 3 main groups:
- Anterior (2-8)
- Middle ( 2-8)
- Posterior (2-6)
Why is it necessary to perform sinus projections upright?
to demonstrate fluid levels
Which projection demonstrates all 4 sets of sinuses?
What is the term Antrum of Highmore?
Old term for maxillary sinuses
Which sinus projection best demonstrates the thickness of frontal bone
For a lateral projection of the sinus, which side is best demonstrated
side closest to IR
Position for a lateral projection of Sinus
10 x 12” IR LW
Lines: MSP is // , IPL & IOML perpendicular to IR
CR enters: 1” posterior to outer canthus
Position for PA Axial projection of sinuses
10 x 12” IR
IR angled 15 degree down
CR exits the nasion
Lines: MSP & OML is perpendicular
Why is using a sponge rather than angling the IR 15 degrees downward not prefered for a caldwell method of sinuses?
Because of increase OID which results in decreases resolution
The Caldwell method best demonstrates which sinuses
Frontal and sphenoid sinuses
What is the method name for the parietoacanthial projection of the sinuses
what does it demonstrate
- Maxillary sinuses
- Frontal and ethmoid sinuses are distorted
In which projection are the frontal and ethmoid sinuses distorted?
Parietoacanthial projection ( Water’s method)
Position for a Water’s method
see series notes
Which projection is the sphenoid sinuses seen through open mouth
Water’s method open mouth
Which sinuses are best seen in the SMV projection
List 2 other structures:
Shenoid and ethomoid
- Bony nasal septum
Position for SMV sinuses
see series notes