Orbits

• Orbit anatomy


  Cone shaped, 7 bones (4 facial, 3 cranial), base, apex, long axis 37° to MSP, 30° superiorly to OML
• Function of orbits


  • Hold eyeballs, opening for blood vessels & nerves
• Bones of the orbit

  • Facial bones: Lacrimal, palantine, zygoma, maxilla

  Cranial bones: Frontal, Ethmoid, Sphenoid
• Fissures & Foramen


  • Superior orbital fissure, Inferior orbital fissure, Optic foramen & canal, Sphenoid strut
• Blowout fracture


  Fracture of floor of orbit, direct blow
• Tripod fracture


  Fracture of zygoma & 3 connections: maxilla, temporal, & frontal
• Routine orbit radiography


  • Parietoacanthial- Waters Method, PA Axial- Caldwell Method, Parieto-orbital oblique- Rhese Method
• Optional orbit radiography


  • Acanthioparietal- Reverse Waters method, AP Axial- Reverse Caldwell, Modified Parietoacanthial- Modified Waters, Orbito-Parietal Oblique- Rhese Method
• Parietoacanthial Projection- Waters


  Erect anterior/prone, "Head above the water", MSP T & centered to IR, OML 37° to I.R, Chin on device, (MML nearly T), No rotation, Lat. Margins of skull to device, CR: T exiting acanthion, Resp: suspend
• PA Axial Projection- Caldwell Method


  Erect anterior/prone, MSP T & centered to IR, OML T to I.R, Forehead & Nose on device, No rotation, Lat. Margins of skull to device, CR: 15° caudal exiting nasion, Resp: suspend
• Parieto-orbital oblique- Rhese Method


  Prone, Rotate MSP 37° from CR, 53° from I.R., AML T to I.R., rest on nose, chin & cheek (3 pt. land.), CR: T, entering 1" post & sup. TEA, Resp: suspend
• MSP rotation


  Moves optic canal & foramen laterally, to outer quadrant
• AML


  Lowers optic canal & foramen to lower quadrant
• Acanthioparietal Projection- Reverse Waters Method (Trauma)


  Supine, MSP T, MML T, OML 37° to IR, CR: Enters acanthion, Still || to MML, May have to angle CR to maintain || position to MML
• Orbits will be magnified in Reverse Waters image
• AP Axial Projection- Reverse Caldwell (Trauma)

  Supine, MSP T, OML T (possibly), CR: ∟to maintain 15° to OML, entering nasion
• Modified Parietoacanthial- Modified Waters

  Erect anterior/prone, "Head above the water", MSP T & centered to IR, OML 55° to I.R, Chin & nose on device, (LML nearly T), No rotation, Lat. Margins of skull to device, CR: T exiting acanthion, Resp: suspend
• Orbitoparietal oblique- Rhese Method


  Supine, Rotate MSP 37° from CR, 53° from I.R., AML T to I.R., CR: T, entering upside orbit, Resp: suspend
• Orbit will be magnified in orbitoparietal oblique Rhese method
• Rhese method is the same for orbitoparietal oblique as other Rhese projections
• Rhese method


  Parieto- orbito oblique

  
• which projection best demonstrates a blowout fx?

  modified parietoacanthial- modified waters
• where should the petrous ridges lie during a modified parieotacanthial - modified waters projection?

  within maxillary sinuses just below floor of orbit
• which projection best demonstrates a tripod fx

  parietoacanthial -waters method
• which orbit is demonstrated during the parieto-orbito oblique rhese method

  the downside orbit
• What pathology is seen on this image?

  Calcified corneas

  
• What is the positioning problem with this waters image?

  Not enough extension

  
• What projection is this image? (positioning is correct)

  Modified Parietoacanthial- Modified waters

  
• If the optic foramen is high in the orbital, and out laterally, what needs to be done?

  Increase extension
• If the optic foramen is in the lower quadrant and inner quadrant, what needs to be done?

  Increase rotation
• What method is also known as the 3 pt. land?

  Rhese method
• Which orbit is placed close to the IR for the Parieto-orbital - Rhese Method?

  The orbit of interest