orbits and TMJS online edition 11 3 2010
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Transcript orbits and TMJS online edition 11 3 2010
What is an Orbit?
Cone-shaped
Bony-walled
Usually 2- one on
each side of
midsagittal plane
Primarily sockets
for eyeballs
Orbit is made up of 7 bones
Note that 4
of bones
are sinus
containing
bones
Typical Orbit projections
Parieto-orbital-- 3 point landing (Rhese)
(Orbitoparietal-- reverse Rhese)
Modified Waters (paritoacanthial)
Lateral
Optic canal (foramina)
Parieto-orbital oblique (Rhese)
3 point landing
chin,cheek, nose
center effected orbit on
IR crosshairs
CR-no angle, perp. To IR
(Adjust flexion of neck to
place acanthomeatal line
is perp. To plane of film)
(Adjust rotation of head
so midsagittal forms 53
deg. Angle with plane of
IR)
Optic Foramina-Parieto-orbital oblique
(Rhese method)
Optic Canal
Orbitoparietal oblique (Rhese)
If a pt. cannot be
done prone
Will increase object
magnification
Greater exposure of
lens of eye
Can be done upright
or recument
Optic Foramina
Modified Waters
Before MRI is performed on any part of
body, if even a suspicion patient has metal
in eye, Waters must be taken
Particulary true in regions with lots of
industry and manufacturing or welders and
mechanics (at UCSF, a CT scan is done)
Why?
Orbits -Waters projection
R
Modified Waters
Similar to
Waters, but
nose and chin
touch IR
OML 50 deg
angle. To IR
Gives better
look into
orbits-less
foreshortening
Modified Waters
Evaluation Criteria
R
Petrous ridges
below orb. rims,
but not below
max. sinus
Orbits
symmetric, no
rotation or tilt
Lateral Orbit projection
L
Similar to
Lateral Sinus
projection
Parieto-orbital oblique
A
B
C
D
E
F
G
A- Superior
orb.margin
B- lat. Orb Margin
C- optic foramin
D-Med.orb. Marg.
E- lesser wing of
sphenoid
F- ethmoids
G- inferior orb.
Marg.
Optic Canal Parieto-orbital
Evaluation Criterion
Optic foramina
R
should lie in inferior
lateral quadrant (4
o’clock or 8 o’clock)
Optic foramina
should be seen
enface at end of
sphenoid ridge
Entire orbital rim
must be shown, with
close beam
restriction
Blowout Fx. of Orbit
Eyeball like small
waterballoon
Fluid of eyeball will
not compress
Eye ball capsule
changes shape when
hit
Force is transferredfloor of orbit is
weakest
Tripod Fx. Of Zygoma
frontal
temp
max
Blow to Zygoma
(malar bone)
breaks frontal,
temporal and
maxillary bones.leaving Zygoma
freely floating
Face is highly vascular- thus heals quickly
This is both good and bad!
Good- fx. heals quickly
Bad- if cheekbone is depressed or out of place,
heals - leaves face mis-shapen - will need to
be rebroken, and reset
Name the 7 bones of Orbit
A- frontal
B- sphenoid
C- palatine
D- zygoma
E- maxillae
F- ethmoid
G- lacrimal
What projections?
A
R
B
L
What is the TMJ?
Where
condyle of
Mandible
inserts into
notch in
Temporal
bone
2 Types of Projections in TMJ Series
AP Axial
Axiolateral
AP Axial TMJ’s
8x10 LW
Similar to Towne (which
is 30 deg to OML, 2 ½ “ above
glabella -how’s that different from 3”
above Nasion?)
Demonstrates
condyles of mandible
and mandibular fossa
of temporal bone
Collimate in!
AP Axial TMJ’s
CR 35 deg.
Caudad
Midway
between TMJs
3” above
nasion
First closed
mouth, then
open if not
contraindicated
AP Axial TMJ’sSupine
AP Axial TMJ’s
Evaluation Criteria
No rotation of head
Minimal
superimposition of
petrosa on condyle
in closed mouth
exam
Open mouth may be
performed if not
contraindict.
Condyle and
temporomandibular
articulation below
pars petrose
TMJ-Axiolateral projection
Temporomandibular Articulations
Axiolateral projections
TMJ Axiolateral projection
Place pt. head lateral
2” above
EAM
1” below EAM
position, effected side
closest to IR (like
lateral skull)
CR enters ½ “ ant.,
2” superior to upside
EAM
CR exits ½ anterior, 1”
inferior to EAM
affected side
CR angled 30 deg.
Caudad
Temporomandibular Articulations
Axiolateral projections
Semi-prone
Closed
open
Temporomandibular Articulations
Axiolateral projection
Erect
Open
Closed
TMJ’s Axiolateral projections
L
?
L
?
All 4 projections are performed for TMJ
Axiolateral Series
Closed
Open
LEFT
Open
Closed
RIGHT
Which is the Open-mouth, and which is the
Closed-mouth Axiolateral TMJ projection?
A
B