1. Mandible & TMJ Lecture
RT 233 Week 7

2. Hello class,
This is my preliminary lecture, I may add more slides over the weekend. Please check back on Sunday evening for any revisions.

3. Mandible

4. Mandible Only movable bone in the skull Densest & largest facial bone
2 bones at birth
Contains mental foramina
The mandible is the largest and densest bone of the face. It is also the only movable bone in the adult skull.
At birth the mandible consists of bilateral pieces held together by a fibrous symphysis that ossifies during the first year of life.
There are 2 holes of each side for the transmission of nerves and blood vessels. These openings are called the mental foramina.

5. Temporomandibular Joint

6. PA Mandible (rami) Seated or Prone Forehead and nose on IR
OML & MSP perpendicular to IR
CR perpendicular to exit acanthion

7. PA Mandible (rami) Radiograph
Mandibular rami and lateral portion of body are visualized
Entire mandible without rotation or tilt

8. PA Mandible Rami- Diagram

9. PA Mandible (body) Seated or Prone
Nose and chin on grid device or table placing mandibular symphysis parallel with plane of IR
AML & MSP perpendicular to IR
CR perpendicular to level of lips

10. PA Mandible (body) Radiograph
Contrast and density are sufficient to view body and rami
Sharp bony detail indicating no motion

11. PA Axial (rami) Mandible Positioning
Seated or Prone
Forehead and nose on IR
OML & MSP perpendicular to IR
CR cephalic, centered to exit acanthion
Pathology demonstrated: fractures and neoplastic/inflammatory processes of the condyloid processes of the mandible.

12. PA Axial (rami) Mandible Radiographs
TMJ and heads of condyles are visible through mastoid processes.
Condyloid processes are well visualized, slightly elongated.
Entire mandible with no rotation or tilt with adequate density

13. PA Axial (body) Mandible Positioning
Seated or Prone
Nose and chin on grid device or table placing mandibular symphysis parallel with plane of IR
AML & MSP perpendicular to IR
CR between TMJ’s, 30 cephalad.

14. PA Axial (body) Mandible Radiographs
TMJ’s just inferior to mastoid process
Symmetric rami
Adequate contrast and density

15. AP Axial – Towne Method OML & MSP perpendicular to IR CR 35-40 caudad
Centered to glabella midway between EAMS and angles of mandible
If IOML is used increase CR angle 7 degrees
IF the area of interest is the TM fossae angle the CR 40 degrees to the OML to reduce superimposition of the TM fossae and mastoid portions of the temporal bone.

16. AP Axial- Towne Method Radiograph
Demonstrates condyloid processes symmetrically
Clear visualization of TMJ fossae and condyle relationship
Minimal SI of TM fossae and mastoid portions

17. Axiolateral Oblique Positioning for Ramus
Seated, semiprone or semisupine
IPL perpendicular to IR
Mouth closed- teeth together
Extend neck, chin jutted forward
CR 25 degrees cephalic to pass through area of interest

18. Axiolateral Oblique Radiograph for Ramus
No overlap of ramus by opposite side of mandible
No elongation or foreshortening of ramus
No superimposition of ramus by c-spine

19. Axiolateral Oblique Positioning for Body
Seated, semiprone or semisupine
IPL perpendicular to IR
Mouth closed- teeth together
Extend neck, chin jutted forward
Rotate pt’s head 30 degrees toward IR
CR 25 degrees cephalic to pass through area of interest

20. Axiolateral Oblique Radiograph for Body
No overlap of body by opposite side of mandible
No elongation or foreshortening of body
No superimposition of body by c-spine

21. Axiolateral Oblique Positioning for Mandibular Symphysis
Seated, semiprone or semisupine
IPL perpendicular to IR
Mouth closed- teeth together
Extend neck, chin jutted forward
Rotate pt’s head 45 degrees toward IR
CR 25 degrees cephalic to pass through area of interest

22. Axiolateral Oblique Radiograph for Mandibular symphysis
No overlap of mentum by the opposite side of mandible
No foreshortening of the mentum region

23. Panorex Mandible Explain how tube/image receptor move
IOML perpendicular
Stand straight, not jutting chin forward
Instruct pt to keep lips together and tongue on roof of mouth

24. Panorex Mandible Radiographs
Demonstrates teeth, mandible, TMJ’s
Density are uniform across image
No artifacts

25. AP Axial Temporomandibular
Supine or seated upright
Posterior teeth closed and in contact
For open mouth- wide as possible without chin jutted forward
OML perp to IR
CR 35 caudad, centered midway between TMJ’s.
Enters approx 3” above nasion

26. AP Axial TMJ Radiograph
No rotation
Minimal superimposition of petrosa on condyle in closed mouth
Condyle and TMJ below pars petrosa in open mouth

27. Axiolateral TMJ Semiprone or seated Center ½” anterior to EAM
Rest cheek on grid device
Rotate MSP approx 15 degrees toward IR
IPL perpendicular
CR 15 caudad exiting through TMJ closest to IR about 1 ½ “ superior to upside EAM

28. Axiolateral TMJ Radiograph
Condyle lying in mandibular fossa in closed mouth
Condyle lying inferior to articular tubercle in open mouth

29. Axiolateral Open mouth

30. Axiolateral Closed mouth