Radiographic Procedures 2 (155) Cranium Exam

PA/PA axial (Caldwell) skull

• patient position:

  • seated upright or prone

  • MSP centered to midline

  • forehead and nose resting on Bucky

• part position:

  • MSP and OML perpendicular to IR

• respiration suspended

• CR:

  • PA: perpendicular to IR, exiting nasion

  • PA axial: 15 degrees caudad, exiting nasion

• collimation:

  • 1 inch beyond skin line of the skull
    

PA skull image criteria

• evidence of proper collimation

• entire cranial perimeter showing three tables of squamous bone

• no rotation:

  • equal distance from lateral borders of skull to lateral border of orbits

  • symmetric petrous ridges

• petrous ridges fill orbits

• penetration of frontal bone without excessive density of lateral borders of skull

PA axial (Caldwell) skull image criteria

• petrous ridges demonstrated in lower third of orbits

AP/AP axial (Reverse Caldwell) skull

• a similar but magnified image when patient cannot be positioned for PA or PA axial

• patient and position part:

  • supine

  • MSP centered to midline

  • MSP and OML perpendicular to IR

• respiration suspended

• CR:

  • AP: perpendicular, enters nasion

  • AP axial: 15 degrees cephalad, enters nasion

• collimation:

  • 1 inch beyond the skin line of the skull

AP/AP axial (Reverse Caldwell) skull image criteria

• shows the same as PA and PA axial projections

• evidence of proper collimation

• entire cranial perimeter showing three tables of squamous bone

• no rotation:

  • equal distance from lateral borders of skull to lateral border of orbits

  • symmetric petrous ridges

• anatomy is more magnified

Lateral skull

• patient position:

  • upright or semiprone

• part position:

  • MSP of head parallel to IR

  • IPL perpendicular

  • IOML perpendicular to front edge of IR

• respiration suspended

• CR:

  • perpendicular to IR

  • enters 2 inches above EAM

• collimation:

  • 1 inch beyond skin line of the skull

Lateral skull image criteria

• entire cranium without rotation or tilt

• superimposed orbital roofs and greater wings of sphenoid

• superimposed mastoid regions, EAMs, and TMJs

• sella turcica in profile

• penetration of parietal region

• no overlap of c-spine by mandible

AP axial (Towne) skull

• patient and part position:

  • supine or upright, seated

  • MSP centered to midline

  • MSP perpendicular

  • OML perpendicular to IR

    • IOML perpendicular if patient cannot flex neck enough

  • top border of IR level with vertex

  • IR centered at or near foramen magnum

• respiration suspended

• CR:

  • directed through foramen magnum

  • OML: 30 degrees cacudal

  • IOML: 37 degrees caudal

• collimation:

  • 1 inch beyond the skin line of the skull

AP axial (Towne) skull image criteria

• no rotation:

  • equal distance from lateral border of skull to lateral margin of foramen magnum

  • symmetric petrous ridges

• dorsum sellae and posterior clinoid process visible within foramen magnum

• penetration of occipital bone without excessive density at parietals

PA axial (Haas) skull

• patient position:

  • prone or upright

  • MSP centered to midline

  • shoulders in same horizontal plane

• part position:

  • forehead and nose resting on Bucky/table

  • MSP perpendicular to IR

  • OML perpendicular to IR

• respiration suspended

• CR:

  • 25 degrees cephalad to OML

  • enters 1 ½ inches below external occipital protuberance

  • exits 1 ½ inches superior to nasion

• collimation:

  • 1 inch beyond the skin line of the skull

PA axial (Haas) skull image criteria

• projection of dorsum sellae and posterior clinoid processes within foramen magnum

• equal distance from lateral border of skull and lateral margin of foramen magnum

• symmetric petrous pyramids

• entire cranium

SMV (Schuller) skull

• patient position:

  • upright (seated) or supine (torso elevated)

• part position:

  • MSP centered to midline

  • MSP perpendicular to IR

  • IOML parallel with IR

  • patient hyperextends neck and rests head on vertex

• respiration suspended

• CR:

  • perpendicular through sella turcica and IOML

  • enters MSP of throat between angles of mandible (gonion)

  • passes through a point ¾ inch anterior to the level of the EAM

• collimation:

  • ½ inch beyond the shadow of the tip of the nose and 1 inch beyond the lateral borders

SMV (Schuller) skull image criteria

• no rotation or tilt:

  • equal distance from lateral border of skull to mandibular condyles

  • symmetric petrous pyramids

• penetration sufficient to demonstrate structures of cranial base

• superimposition of mental protuberance over anterior frontal bone, indicating full neck extension

• mandibular condyles anterior to petrous pyramids

Lateral facial bones

• patient position:

  • upright or recumbent anterior oblique position

• part position:

  • MSP of head parallel with IR

  • IPL perpendicular to IR

  • IOML perpendicular to front edge of the IR

  • zygomatic bone centered to grid

• respiration suspended

• CR:

  • perpendicular to IR

  • enters zygomatic bone halfway between outer canthus and EAM

• collimation:

  • 1 inch beyond shadow of the tip of the nose, superior to ½ inch above supraorbital margins, inferiorly to the gonion, and posteriorly to the EAM

  • no larger than 6 × 10 inches

Lateral facial bones image criteria

• right and left sides superimposed

• all facial bones in entirety with zygomatic bone centered

• no rotation or tilt:

  • almost perfectly superimposed mandibular rami

  • superimposed orbital roofs

  • sella turcica in profile

Parietoacanthial (Waters) facial bones

• patient position:

  • prone or upright

  • center MSP to midline

• part position:

  • rest head on tip of extended chin

    • nose slightly off IR

  • OML adjust to form 37 degree angle with IR plane

  • MML perpendicular to IR

  • MSP perpendicular to IR

  • IR centered to level of acanthion

• respiration suspended

• CR:

  • perpendicular, exits acanthion

• collimation:

  • 1 inch beyond the shadows of the lateral sides of the face, superiory to include the supraorbital margins, and inferiorly to the level of the chin

  • no larger than 8 × 10 inches

Parietoacanthial (Waters) facial bones image criteria

• shows orbits, maxillae, and zygomatic arches

• entire orbits and facial bones

• no rotation or tilt:

  • distances between the lateral borders of the skull and the orbits

  • MSP of head aligned with long axis of collimated field

• petrous ridges projected just below maxillary sinuses

Modified parietoacanthial (modified Waters) facial bones

• head positioned as described using Water’s method

• less extension of the patient’s neck to increase angulation of OML

  • OML is more perpendicular to IR plane

• good to demonstrate blowout fractures

• patient position:

  • prone or upright

  • MSP centered

• part position:

  • rest head on tip of extended chin

    • nose touhcing IR

    • less extension of neck

  • OML forms 55 degree angle with IR plane

  • MML perpendicular to IR

  • MSP perpendicular to IR

  • IR centered at level of acanthion

• respiration suspended

• CR:

  • perpendicular, exiting acanthion

• collimation:

  • 1 inch beyond the shadows of the lateral sides of the face, superiory to include the supraorbital margins, and inferiorly to the level of the chin

  • no larger than 8 × 10 inches

Modified parietoacanthial (modified Waters) facial bones image criteria

• facial bones with less axial angulation than Waters method

• petrous ridges projected just below the inferior border of the orbits at a level midway through the maxillary sinuses

  • orbital floor seen perpendicular to the IR and parallel to the CR
    demonstrates inferior displacement of the orbital floor

  • opacified maxillary sinus

Acanthioparietal (Reverse Waters) facial bones

• patient position:

  • supine

  • MSP centered to midline

• part position:

  • extend chin and neck so OML forms a 37 degree angle with the IR plane

  • MML almost perpendicular

  • MSP perpendicular to IR

• respiration suspended

• CR:

  • perpendicular, enters acanthion

• collimation:

  • 1 inch beyond the lateral sides of the face, superiorly just to the skin shadow, and inferiorly to the chin

  • no larger than 8 ×10 inches

Acanthioparietal (Reverse Waters) facial bones image criteria

• shows orbits, maxillae, and zygomatic arches

• entire orbits and facial bones

• no rotation or tilt:

  • distances between the lateral borders of the skull and the orbits

  • MSP of head aligned with long axis of collimated field

• petrous ridges just below maxillary sinuses

PA axial (Caldwell) facial bones

• patient position:

  • upright (seated) or prone

  • MSP centered to midline

  • forehead and nose resting on Bucky/table

• part position:

  • OML perpendicular to IR

  • MSP perpendicular to IR

  • IR centered to nasion

• respiration suspended

• CR:

  • 15 degrees caudad, exiting nasion

• collimation:

  • 1 inch betond the lateral sides of the face, superiorly to include the supraorbital margins, and inferiorly to the chin

PA axial (Caldwell) facial bones image criteria

• shows:

  • orbital rims

  • maxillae

  • nasal septum

  • zygomatic bones

  • anterior nasal spine

  • petrous ridges in lower third of orbits (caused be 15 degree caudal angle)

• entire orbits and facial bones

• no rotation or tilt:

  • equal distances from lateral borders of skull and lateral borders of orbits

  • MSP of head alligned with long axis of collimated field

• symmetric petrous ridges

Lateral nasal bones

• patient position:

  • upright or recumbent anterior oblique position

  • MSP parallel with IR

• part position:

  • IPL perpendicular

  • flex neck to place IOML parallel to transverse axis of IR

• respiration suspended

• CR:

  • perpendicular

  • enters 1 inch distal to nasion

• collimation:

  • extends from the glabella to 1 inch inferior to the acanthion and ½ inch beyond the tip of the nose

  • should be no larger than 3 × 3 inches

• both sides done for comparison

Lateral nasal bones image criteria

• shows:

  • nasal bone and soft tissues of the nose

  • anterior nasal spine

  • frontonasal suture

  • no rotation

Lateral orbits

• patient position:

  • upright or recumbent anterior oblique position

• part position:

  • outer canthus of affected eye adjacent and centered to IR

  • adjust patient’s head to place MSP parallel with IR

  • IPL perpendicular to IR

  • flex neck to place IOML perpendicular to front edge of IR

• respiration suspended

• CR:

  • perpendicular through outer canthus

Lateral orbits image criteria

• entire orbit(s)

• no rotation

  • superimposed orbital roofs

• close beam restruction centered to orbital region

PA axial (exaggerated Caldwell) orbits

• patient position:

  • upright or recumbent

• part position:

  • rest forehead and nose on IR

  • IR centered ¾ inches distal to nasion

  • adjust head to place MSP and OML perpendicular to IR

• respiration suspended

• CR:

  • 30 degrees caudad, through center of orbits

• non-grid technique recommended to reduce magnification and eliminate possible artificats

PA axial (exaggerated Caldwell) orbits image criteria

• entire orbit(s)

• petrous pyramids lying below orbital shadows

• no rotation:

  • symmetric orbits

• close beam restriction to orbital region

Parietoacanthial (modified Waters) orbits

• patient position:

  • upright or recumbent

• part position:

  • IR centered at level of the center of the orbits

  • rest chin on IR

    • nose lifted way off IR

  • MSP perpendicular to IR

  • flex neck to form 50 degree angle between OML and IR

• respiration suspended

• CR:

  • perpendicular, through mid-orbits

Parietoacanthial (modified Waters) orbits image criteria

• entire orbit(s)

• no rotation:

  • symmetric orbits

• close beam restriction to orbital region

SMV zygomatic arches

• patient position:

  • upright (seated) or supine (torso elevated)

• part position:

  • hyperextend neck to place IOML parallel as much as possible with IR

  • rest head on vertex

  • MSP perpendicular to IR

• respiration suspended

• CR:

  • perpendicular to IOML

  • enters MSP of throat 1 inch posterior to outer canthi

• collimation:

  • 1 inch beyond the lateral sides of the face, superiorly to the chin, and inferiorly to the gonions

  • no larger than 8 × 10 inches

SMV zygomatic arches image criteria

• bilateral symmetric zygomatic arches

• arches free from overlying structures

• no foreshortening of arches

• no rotation or tilt of head

Tangential zygomatic arches

• patient position:

  • upright (seated) or supine (torso elevated)

• part position:

  • hyperextend neck and rest head on vertex

  • IOML as parallel with IR as possible

  • rotate MSP of head 15 degrees toward side being examined

  • tilt top of head 15 degrees away from side being examined

  • center zygomatic arch to IR

• respiration suspended

• CR:

  • perpendicular to IOML

  • centered to zygomatic arch 1 inch posterior to outer canthus

Tangential zygomatic arches image criteria

• one zygomatic arch free of superimposition

• arch not overexposed

AP axial (modified Towne) zygomatic arches

• patient position:

  • upright or supine

• part position:

  • MSP perpendicular to midline

  • OML perpendicular to IR

    • may use IOML if patient can’t flex neck enough

      • increase in CR angle

• respiration suspended

• CR:

  • OML: 30 degrees caudad, enters glabella 1 inch above the nasion

  • IOML: 37 degrees caudad

• collimation:

  • 1 inch beyond the lateral sides of the face, superiorly to the top of the forehead, and inferiorly to the chin

AP axial (modified Towne) zygomatic arches image criteria

• both zygomatic arches, free of superimposition

• no overlap of arches by mandible

• no rotation

  • symmetric arches

• arches projected lateral to mandibular rami

PA mandibular rami

• patient position:

  • prone or upright

• part position:

  • forehead and nose resting on IR

  • OML perpendicular to IR

  • MSP perpendicular to Ir

• respiration suspended

• CR:

  • perpendicular, exits acanthion

• collimation:

  • 1 inch beytond the lateral sides, above the TMJs, and below the chin

PA mandibular rami image criteria

• mandibular body and rami

• central part of body not well shown due to superimposition

• shows medial or lateral displacement of fragments in fractures of the rami

• no rotation or tilt:

  • symmetric mandibular body and rami

  • MSP of head aligned with long axis of collimated field

PA axial mandibular rami

• patient position:

  • prone or upright

• part position:

  • forehead and nose resting on Bucky/table

  • OML perpendicular to IR

  • MSP perpendicular to IR

• respiration suspended

• CR:

  • 20-25 degrees cephalad, exits acanthion

• collimation:

  • 1 inch beyond the lateral sides, above the TMJs, and below the chin

PA axial mandibular rami image criteria

• mandibular body and rami

• central part of body not well shown due to superimposed spine

• demonstrates medial or lateral displace ment of fragments in fractures of the rami

• no rotation or tilt:

  • symmetric mandibular body and rami

  • MSP of head aligned with long axis of collimated field

• condylar processes

PA mandibular body

• patient position:

  • prone or upright

• part position:

  • rest nose and chin on IR

  • anterior surface of the mandibular symphysis parallel to IR'

  • AML nearly perpendicular to IR

  • MSP perpendicular to Ir

• respiration suspended

• CR:

  • perpendicular to level of lips

• collimation:

  • 1 inch beyond the lateral sides, above the TMJs, and below the chin

PA mandibular body image criteria

• shows mandibular body

• no rotation or tilt

  • symmetric mandibular body

  • MSP of head aligned with long axis of collimated field

PA axial mandibular body

• patient position:

  • prone or upright

• part position:

  • rest nose and chin on Bucky/table

  • anterior surface of the mandibular surface parallel to IR

  • AML nearly perpendicular to IR

  • MSP centered and perpendicular to IR

• respiration suspended

• CR:

  • 30 degrees caudad, midway between TMJs

• collimation:

  • 1 inch beyond the lateral sides, above the TMJs, and below the chin

PA axial mandibular body image criteria

• mandibular body and TMJs (condyles)

• TMJs just inferior to the mastoid process

• no rotation or tilt

  • symmetric rami

  • MSP of head aligned with axis of collimated field

Axiolateral and axiolateral oblique mandible

• goal is to place desired portion of the madible parallel with the IR

• patient position:

  • upright in anterior oblique position, semiprone, or semisupine

• part position:

  • head lateral with IPL perpendicular to IR

  • mouth closed with teeth together

  • extend neck to place mandibular body parallel with transverse axis of IR

  • adjust rotation of head to place area of interest parallel to IR

    • ramus: head in true lateral

    • body: rotate head 30 degrees toward IR

    • symphysis: rotate head 45 degrees toward IR

• respiration suspended

• CR:

  • 25 degrees cephalad, passes directly through mandibular region of interest

• collimation:

  • 1 inch beyond the anterior and inferior skin shadows and above the TMJ

Axiolateral and axiolateral oblique mandible image criteria

• shows region of the mandible that was parallel with the IR: ramus, body, or symphysis

• ramus and body:

  • no overlap of the ramu sby opposite side of mandible

  • no elongation or foreshortening of ramus or body

  • no superimposition of the ramus by the cervivcal spine

• symphysis:

  • no overlap of the mentum region by the opposite side of the mandible

  • no foreshortening of the mentum region

SMV mandible

• patient position:

  • upright or supine

• part position:

  • MSP centered to midline

  • neck fully extended

  • head resting on its vertex

  • MSP vertical

  • IOML as parallel as possible with IR

    • if neck cannot be flexed enough, angle the grid device and place it parallel to IOML

• respiration suspended

• CR:

  • perpendicular to IOML

  • centered midway between mandibular angles

  • if neck cannot be flexed enough, angle the tube to be parallel to IOML

• collimation:

  • 1 inch beyond the loateral sides and above the tip of the nose

SMV mandible image criteria

• coronoid and condyloid processes of the rami

• no rotation or tilt

  • equidistant lateral border of skull and mandible

  • MSP of head aligned to long axis of collimated field

• condyles of mandible anterior to pars petrosal

• symphysis extending almost to anterior border of the face

  • mandible not foreshortened

AP axial TMJs

• patient position:

  • supine or upright

  • posterior skull in contact with Bucky/table

• part position:

  • MSP of head perpendicular

  • flex neck to place OML perpendicular to IR

  • one exposure taken with mouth closed

  • one exposure taken with mouth open, if not contraindicated

• respiration suspended

• CR:

  • 35 degrees caudad

  • midway between TMJs, 3 inches above nasion

• collimation:

  • 1 inch beyond the lateral sides, superiorly to the glabella, and inferiorly to the lips

AP axial TMJs image criteria

• mandibular condyles and fossae of the temportal bones

• no rotation of head

• closed mouth: minimal superimposition of petrosa on the condyle

• open mouth: condyle and TMJ below pars petrosa

Axiolateral (modified Schuller) TMJs

• patient position:

  • right or left lateral, both sides done for comparison

  • semiprone or upright

• part position:

  • center ½ inch anterior to the EAM to the IR

  • head in true lateral

  • MSP parallel with IR

  • IPL perpendicular

  • one exposure with the mouth closed, and a second with the mouth open (if not contraindicated

• respiration suspended

• CR:

  • 25-30 caudad

  • enters ½ inch anterior and 2 inches superior to upside EAM

• collimation:

  • 1 inch betond the anterior skin line, posteior and inferior to the TMJs

Axiolateral (modified Schuller) TMJs image criteria

• TMJ with mouth open and closed

• both sides done for comparison

• TMJ anterior to EAM

• closed mouth: condyle in mandibular fossa

• open mouth: condule inferior to the articular tubercle

Axiolateral oblique (modified Law) TMJs

• patient position:

  • semiprone or upright

  • both sides for comparison

  • one exposure made with mouth closed, and one made with the mouth open, if not contraindicated

• part position:

  • center ½ anterior to EAM on the side closest to IR

  • rest cheek against IR

  • rotate MSP of head 15 degrees toward IR

  • IPL perpendicular to IR

  • AML parallel with transverse axis of IR

• respiration suspended

• CR:

  • 15 degreees caudad

  • exits through TMJ closer to IR

  • enters 1 ½ inches superior to upside EAM

• collimation:

  • from the outer canthus to the posterior edge of the auricle and from the midparietal region to the inferior edge of the auricle

Axiolateral oblique (modifed Law) TMJs image criteria

• condyles and necks of the mandible

• relationship between mandibular fossa and condyle

• closed mouth: fractures of the neck and condyle of the ramus

• open mouth: mandibular fossa and inferior and anterior excursion of the condyle

• TMJ articulation

• condyle lying in mandibular fossa in closed-mouth

• condyyle lying inferior to articular tubercle in open-mouth

Lateral sinuses

• patient position:

  • upright anterior oblique

  • can be done in dorsal decubitus position

• part position:

  • head in true lateral

  • MSP parallel to IR

  • IPL perpendicular

  • extend neck so that IOML horizontal and parallel to transverse axis of IR

• respiration suspended

• CR:

  • horizontal and perpendicular

  • enters 1 inch posterior to outer canthus

• collimation:

  • 1 inch beyond the tip of the nose, 3 inches above the nasion, inferior to the occlusal plane, and posteriorly to the auricle

• SID of 72” recommened for preoperative measurements

Lateral sinuses image criteria

• demonstrates:

  • all four sets of sinuses

  • anteroposterior (AP) and superoinferior dimensions of paranasal sinuses

  • thickness of frontal bone

  • detail of side closer to IR

• sphenoidal sinus best demonstrated

• no rotation or tilt

  • sella turcica in profile

  • superimposed orbital roofs

  • superimposed mandibular rami

• air-fluid levels, if present

PA axial (Caldwell) sinuses

• patient position:

  • upright

  • MSP centered to midline

• part position, angled grid technique:

  • tilt vertical Bucky down 15 degrees (horizontal CR)

  • rest forehead and nose on IR

  • center nasion to IR

  • MSP and OML perpendicular to IR

• part position, vertical grid technique:

  • extend neck to rest tip of nose on Bucky

  • OML 15 degrees to horizontal IR

  • sponge can be used to support forehead

  • center nasion to IR

  • MSP perpendicular to IR

  • not preferred because of an increased OID, which results in decreased resolution

• respiration suspended

• CR:

  • horizontal, exits nasion

  • 15 degree relationship between CR and OML

• collimation:

  • 1 inch beyond the lateral skin shadows, superiorly to include just the shadow of the top of the head, and inferiorly to the occlusal plane

PA axial (Caldwell) sinuses image criteria

• demonstrates:

  • frontal sinuses above frontonasal suture

  • anterior ethmoidal air cells

  • sphenoid sinuses seen through nasal fossa below or between ethmoids

  • petrous pyramodis lower third of orbits

• primarily demonstrates the frontal sinuses and anterior ethmoidal air cells

• anterior ethmoidal air cells above petrous ridges

• no rotation or tilt

  • equidistant lateral borders of the skull and lateral borders of the orbits

  • symmetric petrous ridges

  • MSP of head aligned with long axis of collimated field

• air-fluid levels, if present

Parietoacanthial (Waters) sinuses

• patient position:

  • upright

  • MSP centered to midline

• part position:

  • rest chin on vertical grid devie

  • hyperextend neck to place OML at 37 degree angle from IR

  • MSP and MML perpendicular to IR

  • center IR to acanthion

• respiration suspended

• CR:

  • horizontal, exits acanthion

• collimation:

  • 1 inch beyond the lateral skin shadows, superiorly to include just the shadow of the top of the head, and inferiorly to the occulsal plane

Parietoacanthial (Waters) sinuses image criteria

• demonstrates:

  • maxillary sinuses

  • petrous pyramids lying inferior to maxillary floor

  • frontal and ethmoid sinuses are distorted

• insufficient extension: petrosa are projected over the inferior portions of the maxillary sinuses

• overextension: maxillary sinuses are foreshortened, and antral floors are not shown

• OML in proper position:

  • petrous pyramids lying immediately inferior to floor of maxillary sinsues

  • symmetric orbits and maxillary sinuses

  • MSP of head aligned with long axis of collimated field

• air-fluid levels, if present

Parietoacanthial (open-mouth Waters) sinuses

• patient position:

  • upright

  • MSP centered to midline

• part position:

  • rest chin on IR

  • hyperextend neck to place OML at 37 degree angle from IR

  • MSP perpendicular to IR

  • open mouth

• respiration suspended

• CR:

  • horizontal, exits acanthion

• collimation:

  • 1 inch beyond the lateral skin shadows, superiorly to include just the shadow of the top of the head, and inferiorly to the occlusal plane

Parietoacanthial (open-mouth Waters) sinuses image criteria

• demonstrates:

  • sphenoid sinuses through open mouth

  • maxillary sinuses

  • petrous pyramids lying inferior to maxillary floor

    • (OML in proper position)

• no rotation or tilt

  • equidistant lateral borders of skull to lateral border of the orbits

  • summetric orbits and maxillary sinuses

  • MSP of head aligned with long axis of collimated field

• air-fluid levels, if present

SMV sinuses

• patient position:

  • upright

• part position:

  • hyperextend neck and rest vertex of head on Bucky

  • adjust head to place MSP perpendicular to IR plane

  • IOML parallel to IR

• respiration suspended

• CR:

  • horizontal and perpendicular to IOML

  • enters MSP ¾ inch anterior to level of EAM

• collimation:

  • 1 inch beyond the tip of the nose and on the lateral sides

SMV sinuses image criteria

• demonstrates:

  • sphenoid and ethmoid sinuses

  • mandible

  • bony nasal septum

• no tilt:

  • equidistant lateral border of skull to mandibular condyles

• IOML parallel to IR:

  • superimposition of anterior frontal bone by mental protuberancce

  • insufficient neck extension will cause mandible to superimpose ethomoid sinuses

• mandible condyles anterior to petrous pyramids

• air-fluid levels, if present