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 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.

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 Pathology demonstrated: fractures and neoplastic/inflammatory processes of the condyloid processes of the mandible.

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 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.

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 Condyle lying in mandibular fossa in closed mouth Condyle lying inferior to articular tubercle in open mouth

Axiolateral Open mouth

Axiolateral Closed mouth