Skull stuff

head position for PA 0 deg skull

OML perp to IR (// to floor)

where are petrous ridges for the 0 deg skull

at the level of the supraorbital rim

CR angle for Caldwell if OML is // to floor

15 caudad

OML angle for Caldwell if HB is used

15 to the IR (raise chin)

where are petrous ridges for the Caldwell

lower 1/3 of orbits

CR for AP Towne

30 caudad

CR for AP modified Towne

25 caudad

main critique for a properly positioned Townes

dorsum sellae seen through the foramen magnum

head position for LAT skull

IOML // to floor

what is the angle formed between the SOML and the OML

8 degrees

what is the angle formed between the OML and the IOML

7 degrees

positioning for Waters

OML 37 from the IR, or MML // to floor

where are petrous ridges in the Waters

below maxillary sinuses

CR angle for PA axial orbits

30 caudad

where should the petrous ridges be for the PA axial orbits

clears the orbits

another term for the modified parietocanthial waters orbits

shallow waters

describe shallow waters positioning for FB localization

OML 50 from the IR

describe shallow waters positioning for trauma

OML 55 degrees from the IR

where are petrous ridges seen in the shallow waters projection

mid maxillary sinuses

head position for parietocanthial (waters) for zygomatic arches

OML 37 degrees to the IR (MML // to floor)

structures for waters zygomatic arches

both arches + ST

petrous ridge position for waters for zygomatic arches

below the maxillary sinuses

head positioning for Townes zygomatic arches

OML perp to IR

CR for Townes zygomatic arches

30 caudad

appearance of good BTP for Townes arches

bug eye, no foreshortening/elongation of arches

appearance of insufficient caudad beam angle (or chin tuck) for Townes arches

foreshortened arches, looks too AP

appearance of excess caudad beam angle (or chin tuck) for Townes arches

elongation

how to assess rotation on Townes arches

greater distance of arch to mandible = that is the side they’re rotated towards

head position for submentovertical (SMV) zygomatic arches

IOML // to IR (head all the way back, vertex resting on IR)

CR for SMV arches

perp to IOML

how to assess BTP for SMV arches

mentum should SI the frontal bone and be anterior to the ethmoid sinuses

what does excessive angle or neck extension look like for the SMV arches projection

mentum seen anterior to frontal bone, arches are elongated

what does insufficient angle or neck extension look like for the SMV arches projection

mentum seen posterior to frontal bone and ethmoid sinuses

how to assess tilt on the SMV arches projection

equal distance between mandibular rami and lateral skull cortex on both sides; side with the greater distance is the side the vertex is towards

how to assess rotation on the SMV arches projection

bilateral structures on the same transverse plane; head will be rotated towards the more posterior structure

describe the positioning for the Tangential zygomatic arches position

get into SMV position (IOML // to IR), then rotate head 15 deg towards affected side and tilt the vertex 15 deg away from the affected side

for the tangential projection, why do we rotate the head 15 deg towards the affected side

aligns the arch with the LA of the image

for the tangential projection, why do we tilt the head 15 deg away from the affected side

SI the skull and mandible = the arch is in profile

how to assess tilt on the Tangential arch projection

no tilt = arch not SI by mandible or skull

insufficient tilt for Tangential arch projection

mandible and skull not SI, arch not adequately in profile

excessive tilt for Tangential arch projection

mandible seen lateral to the skill edge, mandible may SI the arch

how to assess rotation on Tangential arch projection

arch aligned to the LA of the image

insufficient rotation for Tangential arch projection

arch directed medially, the anterior aspect may SI on the frontal bone

excess rotation for Tangential arch projection

arch directed laterally

purpose of the AP 0 degree mandible projection

assess med/lat fx displacement of the rami

head position for AP 0 deg mandible

OML perp to IR

how to assess proper OML alignment on the 0 degree mandible projection

condyles SI on the mastoids, petrous ridges near/at supraorbital margins, mentum SI between C3-5

how to assess rotation on the 0 degree mandible projection

equal distance between mandibular rami to lateral masses of C spine; rotation towards one side will show a narrowed space on that side, and will show a narrowed ramus

purpose of PA axial mandible

displaces the skull superiorly to show the rami

CR for PA axial mandible

20-25 cephalad

how to assess BTP for the PA axial mandible

rami should be elongated, mentum should be between C6-T1

head position for axiolateral mandible

head in true lateral, raise chin to show mandible free from the C spine

CR angle for axiolateral mandible

25 cephalad (or do HB and tilt their head 25 deg to the IR)

for the axiolateral mandible, which side is the side of interest + where is this on the image

side in contact; the inferior ramus

proper BTP for axiolateral mandible

no SI of remote ramus over the ramus of interest (coronoid may be slightly SI by remote ramus and this is ok)

proper rotation of axiolateral mandible

both rami should be on the same vertical plane; neither is ant/post to the other one

head position for the axiolateral oblique mandible to visualize the body

head lat, rotate head 30 deg to the IR so the body is in contact

head position for the axiolateral oblique mandible to visualize the symphysis

head lat, rotate head 45 deg to the IR so the mentum is in contact

CR for axiolateral oblique mandible

25 cephalad

good BTP for axiolateral oblique mandible

no SI of the remote body/mentum over the affected body/mentum

good rotation/obliquity for the axiolateral oblique mandible

no foreshortening, the affected side should be posterior to the unaffected side due to the obliquity