TMJ Axiolateral Oblique is a radiography positioning projection of the Skull. Axiolateral oblique TMJ. Joint space clear. CR 15° caudad. The centering point is located down-side TMJ (against the IR), where the CR exits. Face turned 15 degrees toward the IR from true lateral. The central ray is CR angled 15° caudad, centered about 1.5 inches (4 cm) above the up-side EAM to pass through the down-side TMJ of interest (modified Law). Image-quality criteria include joint space clearly visualized without cervical spine overlap, condyle centered in articular fossa. A sample technique is 80 kVp with DR 8 or CR 16 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Temporomandibular joint space.
- Mandibular condyle without cervical overlap.
- Articular fossa of temporal bone.
- Articular eminence clearly outlined.
- Condyle-fossa relationship in closed-mouth position.
- Condylar movement in open-mouth variant.
Patient preparation
- Possible fracture or recent injury: do not open the mouth, because fragments can displace. Trauma patients are examined without stress movement of the mandible.
- Verify patient identity.
- Remove glasses, earrings, dentures, hairpins.
- Position patient erect or semiprone with affected side toward IR.
- Turn the face 15 degrees toward the IR from the true lateral position.
- Adjust the IOML perpendicular to the front edge of the IR (Bontrager). Merrill's instead sets the AML parallel to the transverse axis of the IR.
- Closed-mouth position: posterior teeth in contact, not the incisors (Merrill's).
- Open-mouth position, unless contraindicated: open widely (Merrill's; Bontrager prints no distance). Suspend respiration. Examine both sides for comparison.
Position & centering point
Down-side TMJ (against the IR), where the CR exits. Face turned 15 degrees toward the IR from true lateral.
Central ray
CR angled 15° caudad, centered about 1.5 inches (4 cm) above the up-side EAM to pass through the down-side TMJ of interest (modified Law).
Exposure / technique
- kVp
- 80
- mAs
- DR 8 / CR 16
- SID
- 40" (102 cm)
- Notes
- CR angle 15 degrees caudad. Head rotation 15 degrees for oblique. Never open the mouth with possible fracture or recent injury. Sample technique: DR 8 / CR 16 mAs at 80 kVp, 40 in SID, for a 15 cm part. Adjust for your equipment.
kVp and mAs are sample values. Use caution when applying them in your department.
Image-quality criteria
- Joint space clearly visualized without cervical spine overlap.
- Condyle centered in articular fossa.
- Mandibular condyle and temporal articular surface outlined.
- No superimposition by cervical vertebrae.
- Detail of condylar process and articular surfaces.
- TMJ closest to the IR shown without superimposition of the opposite TMJ.
Common errors
- 1 Head not rotated 15 degrees: the opposite TMJ superimposes the TMJ of interest.
- 2 TMJ of interest superimposed by the cervical spine.
- 3 Tilt: IPL not perpendicular to the IR.
- 4 Closing on the incisors protrudes the mandible and carries the condyles out of the fossae (Merrill's).
Clinical indications
- Abnormal relationship or range of motion between the condyle and TMJ fossa.
- Fractures of the neck and condyle of the ramus: closed-mouth position only (Merrill's).
- TMJ functional evaluation: closed vs. open mouth.