The Mandible 3/10/2012
What are the alveolar processes? Bony portions of maxilla and mandible where teeth are embedded and by which tooth roots are supported
The Mandible is one of two non-paired bones of the faceWhat is the other? If you said Occipital- you are wrong! That is a cranial bone! It’s the Vomer!
Basic Routine Projections for Mandible PA Bilateral Axiolateral Obliques SMV (optional)
Notice- there is no lateral projection- why not? The two halves of mandible would be superimposed-thus obscuring information for both sides.
Mandible-PA-Ramus(General survey) Similar to a PA skull-nose and forehead against IR CR- 0 Degrees Exit at tip of nose (acanthion) 8x10 cassette, collimated (body and mentum superimposed on spine)
PA Mandible -Body • Ramus • Mentum • Body • Angle
PA Mandible-Body • Similar to PA for Ramus, except chin and nose against IR • 0 degree CR angle
PA Mandible-Evaluation Critera Mandibular body and rami symmetric include entire mandible collimate Interpupillary line horizontal midsag.plane perpendicular
A pretty decent AP mandible can be obtained by doing aC-spine odontoid R
Mandible-axiolateral oblique Both left and right oblique projections must always be performed! Blow to one side of jaw transfers force to opposite side, possibly breaking that side, not necessarily fracturing side of impact. 1975- 2nd year Radiology student
Body- 30 deg. int. rotated Symphysis 45 deg. int. rotated Ramus -lateral 3 variations of Mandibularaxiolateralobliques CR angled 25 deg. cephalic
Mandibular Axiolateral oblique for Ramus Head true lateral CR angled 25degrees cephalic extend chin to avoid superimposition on spine
Axiolateral oblique-Ramus TMJ A CONDYLE B CORONOID C RAMUS D BODY E ANGLE F
Axiolateral oblique - MandibularBody Similar to ramus oblique, but rotate head 30 degrees to IR (mand. Body of interest will be parallel to IR) CR 25 degrees up through area of interest
-no overlap of body by opposite body no cervical spine superimposition no distortion of body Evaluation criteria Axiolateral oblique-mandibular body
Evaluation criteria Mandibular Axiolateral oblique - symphysis No overlap of mentum no foreshortening (spine will overlap body)
Mandible-axiolateraloblique LAO LPO Shoulder super-imposition problem!
Mandible-axiolateraloblique(tip!) Why struggle to get patient into zero tilt lateral, and then angle 25 degrees up? Use tilted head to your advantage! tilt of head + CR angle 25 degrees
Mandible -SMV(optional) For visualizing mandibular body and coronoid & condyloid processes of rami
Mandible -SMV • Similar to skull, but collimated to anterior portion of cranium • IOML parallel to IR (tilt cassette forward if possible) • CR Perpendicular to IOML, midway between angles of mandible
Mandible- SMVEvaluation Criteria Symphysis A Body B Coronoid process C Distance between lateral border of skull and mand. Equal on both sides condyles anterior to pars petrosae Symphysis extendng to anterior border of face Ramus D Condyle E F Petrous ridge
What is the only bone of the human body that does not articulate with any other bone? The Hyoid Bone!
Hyoid Bone • Attaches from the styloid processes of temporal bone to tongue • No views to demostrate
While not always necessary or useful, it is best to give the patient as much shielding as they feel they need for their safety--
REVIEW • A- Coronoid process • B- mandibular fossa • C- neck of condyle • D- Condyle • E- condylar process • F- Ramus • G- Gonion • H- Body • I-Alveolar process