Head
50 Facial Bones
Anatomy
The facial bones include 14 bones: two maxillae, two zygomatics, two palatines, two nasal bones, two lacrimal bones, two inferior nasal conchae, the vomer, and the mandible. These bones form the framework of the face, house the upper teeth, and contribute to the structure of the orbits and nasal cavity.
Key structures relevant to imaging:
- Zygoma (cheekbone)
- Maxillae and anterior nasal spine
- Nasal septum (vomer + perpendicular plate of ethmoid)
- Orbital margins/floors
- Mandible
Facial Bones – Routine Projections
Lateral Facial Bones – Right or Left
Clinical Indications
-
Fractures and neoplastic or inflammatory processes of the facial bones, orbits, and mandible.
CR Location & Positioning
- SID: 40″ (102 cm)
- Patient position: Erect or recumbent semiprone, lateral side of interest against IR.
- Adjustments:
- MSP parallel to IR.
- IPL perpendicular to IR.
- IOML perpendicular to front edge of IR.
- Oblique body slightly for comfort if erect.
- CR: Perpendicular to zygoma (midway between outer canthus and EAM).
- Pt. Instructions: Suspend respiration.
- Exposure: 65–80 kV.
Evaluation Criteria
- Coverage: Entire facial bone region from orbital roofs to mandible, including zygoma.
- Rotation checks:
- No rotation → mandibular rami and greater wings of sphenoid superimposed.
- No tilt → orbital roofs superimposed.
- Motion checks: Sharp bony margins.
- Technique checks: Adequate contrast/density to visualize maxillary and orbital detail.
Parietoacanthial (Waters Method) Facial Bones
Clinical Indications
-
Tripod and Le Fort fractures, orbital floor fractures, foreign bodies, neoplastic/inflammatory disease.
CR Location & Positioning
- SID: 40″ (102 cm)
- Patient position: Erect (preferred) or prone. Chin against IR.
- Adjustments:
- MML perpendicular to IR → OML forms ~37° angle.
- MSP perpendicular to IR, no rotation/tilt.
- CR: Perpendicular to IR, exiting at acanthion.
- Pt. Instructions: Suspend respiration.
- Exposure: 70–85 kV.
Evaluation Criteria
- Coverage: IOMs, maxillae, nasal septum, zygomatic bones, anterior nasal spine.
- Rotation checks: Equal distance from lateral orbital margins to cranial cortex.
- Motion checks: Sharp bony margins.
- Technique checks: Petrous ridges projected just inferior to maxillary sinuses; sufficient density for orbital and maxillary detail.
Clinical Tip:
If patient cannot extend the neck enough to place MML perpendicular, accept a slightly steeper OML angle but confirm that petrous ridges fall just below maxillary sinuses.
PA Axial (Caldwell Method) Facial Bones
Clinical Indications
-
Facial fractures, orbital rim fractures, and pathology of the nasal septum and anterior maxillae.
CR Location & Positioning
- SID: 40″ (102 cm)
- Patient position: Erect (preferred) or prone. Forehead and nose against IR.
- Adjustments: OML perpendicular to IR; MSP perpendicular.
- CR: 15° caudad to exit at nasion. (30° caudad if orbital floors are area of interest.)
- Pt. Instructions: Suspend respiration.
- Exposure: 70–85 kV.
Evaluation Criteria
- Coverage: Orbital rim, maxillae, nasal septum, zygomatic bones, anterior nasal spine.
- Rotation checks: Equal distance midlateral orbital margin to lateral skull cortex; symmetric superior orbital fissures.
- Motion checks: Sharp bony margins.
- Technique checks:
- 15° caudad → petrous ridges in lower 1/3 of orbits.
- 30° caudad → petrous ridges below IOM, better orbital floor view.
Clinical Tip:
If orbital floors are primary concern, use the 30° caudal angle for optimal orbital visualization.
Special – Modified Parietoacanthial Facial Bones (Modified Waters Method)
Clinical Indications
-
Orbital fractures (blowout), foreign bodies, less distorted orbital rim view.
CR Location & Positioning
- SID: 40″ (102 cm)
- Patient position: Erect (preferred) or prone. Chin and nose against IR.
- Adjustments: LML perpendicular; OML forms ~55° with IR.
- CR: Perpendicular, exiting at the acanthion.
- Pt. Instructions: Suspend respiration.
- Exposure: 70–85 kV.
Evaluation Criteria
- Coverage: Orbital floors perpendicular to IR; orbital rims visualized with minimal distortion.
- Rotation checks: Equal distance midlateral orbital margin to lateral cranial cortex.
- Motion checks: Sharp bony margins.
- Technique checks: Petrous ridges in lower half of maxillary sinuses, below IOMs.
Clinical Tip:
This view is particularly useful for “blowout” fractures—orbital floor is demonstrated without superimposition.
Facial Bones – Trauma Projections
Acanthioparietal Projection (Reverse Waters Method)
CR Location & Positioning
- SID: 40 inches (102 cm)
- Patient position: Supine, usually immobilized on backboard or table.
- Adjustments: Do not move head/neck. Align CR cephalad, parallel to MML (mentomeatal line).
- CR: Directed cephalad to acanthion, parallel to MML. Center IR to projected CR.
- Pt. Instructions: Remain still; no movement of head/neck.
- Exposure: Suspend respiration.
Evaluation Criteria
- Coverage: Maxillae, maxillary sinuses, zygomatic arches, nasal septum, and orbits above petrous ridges.
- Rotation checks: Equal distance from midlateral orbital margins to cranial cortex.
- Motion checks: Sharp bony margins; no motion blur.
- Technique checks: Contrast and brightness sufficient to demonstrate maxillary region and orbital structures.
- Clinical aim: Demonstrates facial bone structures and maxillary sinuses free of superimposition by petrous ridges.
Modified Acanthioparietal Projection (Modified Reverse Waters Method)
CR Location & Positioning
- SID: 40 inches (102 cm)
- Patient position: Supine, immobilized.
- Adjustments: Do not manipulate head/neck. Align CR cephalad, parallel to LML (lips–meatal line).
- CR: Directed cephalad to acanthion, parallel to LML. Center IR to projected CR.
- Pt. Instructions: Remain still.
- Exposure: Suspend respiration.
Evaluation Criteria
- Coverage: Orbital floors and rims, maxillae, nasal septum.
- Rotation checks: Equal distance from lateral orbital margins to cranial cortex.
- Motion checks: Sharp bony detail throughout.
- Technique checks: Petrous ridges projected into midmaxillary sinus region, below orbital rims.
- Clinical aim: Best for demonstrating orbital floor fractures (blowout) and orbital rim integrity.
Lateral Facial Bones – Trauma (Horizontal Beam)
CR Location & Positioning
- SID: 40 inches (102 cm)
- Patient position: Supine; immobilized on backboard.
- Adjustments: IR placed vertically at side of head, closest to area of interest.
- CR: Horizontal beam, perpendicular to IR, centered to zygoma (midway between outer canthus and EAM).
- Pt. Instructions: Remain still.
- Exposure: Suspend respiration.
Evaluation Criteria
- Coverage: Superimposed facial bones, zygomatic arch, mandible, orbital roofs, sphenoid wings.
- Rotation checks: Superimposition of mandibular rami and orbital roofs.
- Motion checks: Crisp margins of facial bones.
- Technique checks: Adequate contrast to show facial structures and soft tissue detail.
- Clinical aim: Detects fractures, foreign bodies, and air-fluid levels (especially sphenoid sinus, useful for basal skull fracture assessment).
Projection | CR Location & Angle | Patient Position | Key Evaluation Points |
---|---|---|---|
Lateral | Perpendicular to zygoma (midway between outer canthus & EAM) | Erect or recumbent, side of interest closest to IR; MSP ∥ IR; IPL ⟂ IR; IOML ⟂ front edge of IR | • Facial bones superimposed • Mandibular rami & orbital roofs aligned (no rotation/tilt) • Sharp margins, zygoma centered |
Parietoacanthial (Waters) | Perpendicular, exiting at acanthion | Erect preferred; chin against IR; MML ⟂ IR (OML ~37° to IR); MSP ⟂ IR | • Petrous ridges just below maxillary sinuses • IOMs, maxillae, zygomas, nasal septum included • Equal orbital margins (no rotation) • Sharp bone detail |
PA Axial (Caldwell) | 15° caudad to exit nasion (30° if orbital floors) | Erect preferred; forehead & nose on IR; OML ⟂ IR; MSP ⟂ IR | • 15° → petrous ridges in lower 1/3 of orbits • 30° → petrous ridges below IOMs, orbital floors better seen • Symmetry of orbits and superior orbital fissures |
Modified Waters (Parietoacanthial) | Perpendicular, exiting at acanthion | Erect preferred; chin & nose on IR; LML ⟂ IR (OML ~55° to IR); MSP ⟂ IR | • Orbital floors seen with minimal distortion • Petrous ridges in lower ½ of maxillary sinuses • Equal orbital margins (no rotation) • Best for orbital “blowout” fractures |
Trauma – Reverse Waters | Angle CR cephalad to acanthion, ∥ MML | Supine; no head/neck manipulation; IR centered to CR | • Maxillae & maxillary sinuses projected above petrous ridges • Equal orbital margins (no rotation) • Useful when patient cannot extend neck |
Trauma – Modified Reverse Waters | Angle CR cephalad to acanthion, ∥ LML | Supine; no head/neck manipulation; IR centered to CR | • Orbital floors and rims demonstrated • Petrous ridges in midmaxillary sinus region • Best for orbital floor fx in trauma patients |
Trauma – Lateral (Horizontal Beam) | Horizontal CR ⟂ IR, centered to zygoma (midway between outer canthus & EAM) | Supine; immobilized; IR vertical at side of head closest to area of interest | • Facial bones superimposed • Mandibular rami & orbital roofs aligned • Detects air-fluid levels in sphenoid sinus (basal skull fx sign) |
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Hows & Whys of Facial Bone Radiography