The Mandible 3/10/2012

The mandible is the largest, densest bone of the face

PA Mandible

Lateral Mandible

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 face What 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.

Don’t try this at Work!

Panoramic Tomography (Panorex)

Mandible-PA - Ramus

) 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 Ramus Mentum Mentum Body Body Angle Angle

PA Mandible-Body Similar to PA for Ramus, except chin and nose against IR 0 degree CR angle

PA - Body PA - Ramus

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 a C-spine odontoid R

Mandible- axiolateral oblique Both left and right oblique projections must always be performed! nd year Radiology student, possibly breaking that side, not necessarily fracturing side of impact. Blow to one side of jaw transfers force to opposite side, possibly breaking that side, not necessarily fracturing side of impact.

3 variations of Mandibular axiolateral obliques CR angled 25 deg. cephalic Ramus -lateral Body- 30 deg. int. rotated Symphysis 45 deg. int. rotated

Mandibular Axiolateral oblique for Ramus Head true lateral CR angled 25 degrees cephalic extend chin to avoid superimposition on spine

Axiolateral oblique-Ramus TMJ CONDYLE CORONOID RAMUS BODY ANGLE A B C D E F

Axiolateral oblique - Mandibular Body 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

Axiolateral oblique-mandibular body -no overlap of body by opposite body no cervical spine superimposition no distortion of body Evaluation criteria

Mandibular Axiolateral oblique - symphysis No overlap of mentum no foreshortening (spine will overlap body) Evaluation criteria

Mandible-axiolateral oblique LAOLPO Shoulder super-imposition problem!

Mandible-axiolateral oblique (tip!) Why struggle to get patient into zero tilt lateral, and then angle 25 degrees up? 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

SMV projection

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 Similar to skull, but collimated to anterior portion of cranium IOML parallel to IR (tilt cassette forward if possible) IOML parallel to IR (tilt cassette forward if possible) CR Perpendicular to IOML, midway between angles of mandible CR Perpendicular to IOML, midway between angles of mandible

SMV- alternate projection

Mandible- SMV Evaluation Criteria Distance between lateral border of skull and mand. Equal on both sides condyles anterior to pars petrosae Symphysis extendng to anterior border of face A B C D E F Symphysis Body Coronoid process Petrous ridge Condyle Ramus

The Hyoid Bone! What is the only bone of the human body that does not articulate with any other 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