Paranasal Sinuses

Paranasal sinuses are

large air filled cavities lined with mucous membranes

What is the function of paranasal sinuses

Communicate with nasal cavity

Produce mucus to moisten nasal passageways

The four groups of paranasal sinuses

Maxillary

Front

Ethmoid

Sphenoid

Which paranasal sinus is the last to develop?

Ethmoid around 17-18

Coronal view of sinuses

Osteomeatal complex

Pathways of communication between sinus and nasal cavity once all sinuses are fully developed

Maxillary sinuses are where

within facial bone, maxilla

Shape of maxillary sinuses

2 pyramid shape

Maxillary sinus orientation

In maxilla

Above upper teeth

For maxillary sinuses, since it is above upper teeth

infection can travel to sinuses

Frontal sinus are located where

Inner and outer tables of frontal bone

The frontal sinuses are rarely

symmetric

Number of frontal sinuses

1-2

sometimes may even be absent

The frontal sinus is larger in

males

Ethmoid sinuses are located where

within the lateral masses of the ethmoid bone

How many collections of ethmoid sinuses

3

anterior, middle, and posterior

The sphenoid sinuses are located where

Below the sella turcica

at the base of the skull

How many sphenoid sinuses

1-2

Sphenoid sinus may indicate what type of fracture

Basal skull fracture/sphenoid effusion

A basal skull sinus is when

blood and CSF leaks into the sphenoid sinus

sphenoid effusion

Paransal Sinus Basic Routine

Lateral

PA Caldwell

Parietoacanthial (waters)

Submentovertex (SMV)

Special views for paranasal sinuses

Parietoacanthial transoral (open mouth Waters)

Paranasal sinus exams should be

erect to demonstrate air fluid levels

Sinus radiograph demonstrations

Lateral Sinus patient positioning

upright in oblique position

What lines are involved in lateral sinus

IOML

IPL

MSP

In lateral sinus, IOML is

parallel to IR or perpendicular to the front edge of the IR

In lateral sinus, the IPL is

perpendicular to the IR

MSP in lateraal sinus is

parallel to IR

Collimation for lateral sinus

1/2-1'' beyond nose

3'' above nasion

Inferior to include occlusal plane

Central ray for lateral sinus

1/2-1'' posterior to outer canthus

What sinuses do you see on lateral sinus projection

All 4 sinuses

Superimposed facial bones

How can you tell rotation on lateral sinus

Greater wing not superimposed

Mandibular rami not superimposed

How can you tell tilt on lateral sinus

Orbital roofs not superimposed

Optimal exposure on lateral sinus if

able to see maxillae and sella turcica in profile

For a PA Axial Caldwell for sinuses, there is no

tube angulation

The OML for PA Axial Caldwell for sinuses needs to be

15 degree superiorly from horizontal

Collimation for PA Axial Caldwell for sinuses

1'' beyond lateral border of skull

Shadow of top of head and the occlusal plane

CR for PA Axial Caldwell Sinuses

Horizontal exiting through the nasion

The PA Axial Caldwell Sinus shows which sinuses

frontal sinus

anterior ethmoid sinuses

The petrous ridges in PA axial caldwell sinus should be placed

in lower 1/3 of orbit

How can you tell rotation on PA Axial Caldwell Sinus

Equal distance from orbit to lateral cortex of cranium

How can you tell tilt on PA Axial Caldwell Sinus

orbits on the same plane

You dont want to tilt down because

you do not want to distort the air fluid levels

PA Parietoacanthial Waters patient positioning

upright in the middle of the IR

Collimation for Parietoacanthial Waters view

1'' lateral to the skull border, shadow of the top of head, and inferiorly to the occlusal plane

What lines are involved in Parietoacanthial (waters)

MML-perpendicular to the IR

or OML-37 from horizontal

MSP

The MML for parietoacanthial (waters) should be

perpendicular to the IR

In a parietoacanthial (waters)

hyperextend the neck to make the MML perpendicular to the IR

or

OML 37 degrees from horizontal!!

central ray for parietoacanthial (waters)

perpendicular to the IR to exit at acanthion

What sinuses do you see on parietoacanthial waters?

Maxillary sinuses

In the parietoacanthial waters view, the petrous ridges

should be below the maxillary sinuses

How can you tell rotation on parietoacanthial waters view

equal distance from lateral border of orbit to cranium

symmetrical maxillary sinuses

Parietoacanthial Transoral Waters

Special view to see sphenoid sinuses

Patient positioning for parietoacanthial transoral waters

upright with MSP in the middle of the IR

What lines are involved for parietoacanthial transoral waters

MML perpendicular to IR

OML 37 degrees from horizontal

Collimation for parietoacanthial transoral waters

1'' lateral to skull border, shadow of the top of head, and inferiorly the occlusal plane

PA Transoral waters shows what sinuses

SPHENOID

front and maxillary sinuses also included

In transoral waters, the petrous ridges should be

below the maxillary sinuses

How can you tell a PA transoral waters is not rotated

Equal distance between lateral border of skull and lateral border of orbit

Symmetrical orbits

Symmetrical maxillary sinuses

What is the best view to see the sphenoid sinus?

PA transoral waters

Patient positioning for SMV sinuses

erect

What lines are involved with SMV

IOML-parallel to the IR

MSP-perpendicular to the IR

Central ray for SMV sinus

1.5'' below mandibular symphysis between angles of the mandible (3-4'' anterior to EAM)

What sinuses should you see in SMV

Ethmoid and sphenoid sinuses

In an SMV sinus, the mandibular condyles should be

anterior to petrous ridges

How can you tell tilt on SMV

Equal distance between mandibular rami and lateral cranium