RAD 233 Nasal bone & Paranasal Sinuses

Defined as the air-filled cavities located in the frontal, ethmoid, and sphenoid bones of the cranium, as well as the maxillae of the face

Paranasal sinuses

Why is the reason for Paranasal Sinuses to be named?

Their formation from the nasal mucosa and their continued
communication with the nasal fossae

The Paranasal serve as a resonating chamber for the…

Voice

Does the Paranasal help increase or decrease the weight of the skull?

Decrease

How does sinuses aid when air is inhaled?

warms and moisten air

What acts as shock absorbers in trauma?

Paranal sinuses

How is sinuses related with immune systems?

It can possibly control the immune system

When does the development of the sinuses begin ?

Begin at fetal life (9wks of pregnancy)

What sinuses are usually the only ones developed enough to be demonstrated radiographically at birth

Maxillary

At what age does the frontal and sphenoid sinus develop?

6 to 7 years

When do the ethmoid sinuses fully develop?

17 to 18 yrs

Largest and most symmetric sinus?

Maxillary

Maxillary sinuses vary in size and shape, but are approximately what shape?

pyramidal

How do the maxillary sinus appear on lateral radiographs?

Appear rectangular

What’s the heigh and width of the maxillary?

H→ 1in

W→ 1-1.3in

With what does the maxillary sinuses communicate?

middle nasal meatus at the superior aspect of sinus

Second largest, located between vertical plates of frontal
bone and vary greatly in size and shape

Frontal sinus

what’s the size of the frontal sinus

3/4-1in

Why is frontal sinuses occasionally absent?

Because some people don’t develop them

Are frontal sinus symmetric or asymmetric

asymmetric (rarely symmetric)

What divides the frontal sinus usually deviated from the midline

intersinus septum

The frontal sinus drain into?

Middle nasal meatus

Normally paired, Occupy body of sphenoid bone, Vary in size and shape

Sphenoid sinuses

How many sphenoid sinus develop?

Often only one sinus develops, but never more than two

Are sphenoid sinuses symmetric or asymmetric

asymmetric

where are the sphenoid sinuses located?

Located below sella turcica and extend between dorsum and posterior ethmoids

The sphenoidal sinus open into the ?

Sphenoethmoidal recess

Located within lateral masses of labyrinths

Ethmoid sinuses

Composed of varying number of air cells, which are divided into three main groups which are?

Anterior (2-8)

Middle (2-8)

Posterior (2-6)

How is the IOML and MSP for the Lat Nasal Bone

Parallel

How is the IPL for the Lat Nasal Bones

Perpendicular

CR for Lat Nasal Bones

Perpendicular to bridge of nose enters 1 in distal to nasion

Collimation for Lat Nasal bones

3×3 in

How many of the sinuses are demonstrated with the Lat paranasal projection

All 4 sets

Which sinus is best demonstrated in the Lat paranasal

sphenoid sinus

What dimensions of the sinuses are demonstrated with Lateral paranasal

Anteroposterior (AP) and superoinferior

What of the frontal bone is demostrated w/ the Lat Paranasal

The thickness of frontal bone

Which side is demonstrated w/ the Lat paranasal

Detail of side closer to IR

How should the MSP and IPL be for the Lat paranasal

MSP → parallel

IPL→ Perpendicular

How is the IOML to the front edge of the IR

Perpendicular

CR for the Lat paranasal

Horizontal/Perpendicular to IR entering ½ to 1 in posterior to outer canthus

For Caldwell method where are the frontal sinus seen

Above frontonasal suture

which of the ethmoid air cells is seen w/ the Caldwell method?

Anterior

Where are the sphenoid sinuses seen for the Caldwell method?

Through nasal fossa below or between ethmoids

How many degrees should the bucky be tilted down for the Caldwell method

15 degrees

How is the OML and MSP to the IR for the tilted grid Caldwell method?

perpendicular

The OML is placed how many degrees from the CR using the tilted grid Caldwell?

15 degrees

For the Vertical Grid Technique Caldwell the OML should be positioned how many degrees from the CR

15 degrees

how is the MSP for the Vertical Grid Technique Caldwell?

perpendicular

What can be used to support the forehead for the Vertical Grid Technique Caldwell

radiolucent support

Why is the Vertical Grid Technique Caldwell not preferred?

Increases OID→ decreases resolution

CR for Caldwell method

Horizontal/Perpendicular exiting nasion

The Caldwell method is mostly used to demonstrate what ?

Frontal sinus and anterior ethmoidal air cells

What sinus is of main interest when performing the waters method for the paranasal?

Maxillary sinus

When the neck is extended too little for the water method the petrosae are projected where?

over inferior portion of maxillary sinus, obscures underlying pathologic condition

When the neck is extended too much for the water method what happens?

maxillary sinuses are foreshortened, and the antral floors are not shown

How the Frontal and ethmoid sinuses shown for the waters method?

Distorted

How many degrees is the OML from the IR in waters method

37 degrees

How is the MSP and MML for the waters method

perpendicular

CR for waters method

horizontal exiting acanthion

Petrous pyramids lying inferior to maxillary floor shows what ?

Proper neck extension for the waters method

The Open-Mouth Waters Method shows what?

Sphenoid sinuses through open mouth

When is the Open-Mouth Waters Method used?

when the patient can’t be placed in position for the SMV projection to see sphenoid sinus

What’s the only difference in positioning for the Open-Mouth Waters Method

the patient wide opens their mouth

what sinuses are seen w/ the Open-Mouth Waters Method?

sphenoid and maxillary

What sinuses are demonstrated when performing the Submentovertical Projection

Ethmoid and sphenoid sinuses

What other structures are seen w/ the SMV

Mandible and Bony nasal septum

PT position for the SMV

Hyperextend neck and rest vertex of head on vertical grid device

How is the MSP to the IR for the SMV

Perpendicular

How is the IOML to the IR for the SMV

parallel

How is the IOML to the CR for the SMV

perpendicular

CR for SMV

Horizontal and perpendicular to the IOML through the sella turcica. The central ray enters on the MSP approximately inch (1.9 cm) anterior to the level of the EAM

What happens when the neck is extended insufficiently

Will cause mandible to superimpose ethmoid sinuses