Mandible & TMJ Lecture

RT 233 Week 7

Hello class, This is my preliminary lecture, I may add more

slides over the weekend. Please check back on Sunday evening for any revisions.

Mandible

Mandible

Only movable bone in the skull

Densest & largest facial bone

2 bones at birth

Contains mental foramina

Temporomandibular Joint

PA Mandible (rami)

Seated or Prone

Forehead and nose on IR

OML & MSP perpendicular to IR

CR perpendicular to exit acanthion

PA Mandible (rami) Radiograph

Mandibular rami and lateral portion of body are visualized

Entire mandible without rotation or tilt

PA Mandible Rami- Diagram

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

PA Mandible (body) Radiograph

Contrast and density are sufficient to view body and rami

Sharp bony detail indicating no motion

PA Axial (rami)Mandible Positioning Seated or Prone

Forehead and nose on IR

OML & MSP perpendicular to IR

CR 20- 25 cephalic, centered to exit acanthion

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

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.

PA Axial (body)Mandible Radiographs

TMJ’s just inferior to mastoid process

Symmetric rami

Adequate contrast and density

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

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

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

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

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

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

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

Axiolateral Oblique Radiograph for Mandibular symphysis

No overlap of mentum by the opposite side of mandible

No foreshortening of the mentum region

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

Panorex Mandible Radiographs

Demonstrates teeth, mandible, TMJ’s

Density are uniform across image

No artifacts

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

AP Axial TMJ Radiograph

No rotation

Minimal superimposition of petrosa on condyle in closed mouth

Condyle and TMJ below pars petrosa in open mouth

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

Axiolateral TMJ Radiograph

TMJ

Condyle lying in mandibular fossa in closed mouth

Condyle lying inferior to articular tubercle in open mouth

Axiolateral Open mouth

Axiolateral Closed mouth