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 Similar to Lateral Sinus projection L

Parieto-orbital oblique  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. A B C D E F G

Optic Canal Parieto-orbital Evaluation Criterion  Optic foramina 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 R

Blowout Fx. of Orbit  Eyeball like small waterballoon  Fluid of eyeball will not compress  Eye ball capsule changes shape when hit  Force is transferred- floor of orbit is weakest

Tripod Fx. Of Zygoma  Blow to Zygoma (malar bone) breaks frontal, temporal and maxillary bones.- leaving Zygoma freely floating temp frontal max

Face is highly vascular- thus heals quickly  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 This is both good and bad!

Name the 7 bones of Orbit   A- frontal   B- sphenoid   C- palatine   D- zygoma   E- maxillae   F- ethmoid   G- lacrimal

What projections? R L A B

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  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’s- Supine

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 position, side closest to IR (like lateral skull)  Place pt. head lateral position, effected side closest to IR (like lateral skull)  CR to EAM  CR enters ½ “ ant., 2” superior to upside EAM  CR, to EAM affected side  CR exits ½ anterior, 1” inferior to EAM affected side  CR angled 30 deg. Caudad 2” above EAM EAM 1” below EAM

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 LEFT RIGHT Open Closed

Which is the Open-mouth, and which is the Closed-mouth Axiolateral TMJ projection? A B