The skull Flashcards
What is another name for the PA skull?
Ruggles Method
What is another name for PA Axial skull?
Caldwell Method
What is another name for AP Axial skull?
Towne Method
What is another name for the Submentovertical – SMV skull?
Schϋller Method (Basal View)
What is skull type determined by?
- The angle of the petrous ridges to the MSP
- Cephalic Index
What is the angle between MSP and petrous pyramids for the Mesocephalic skull?
47 degrees
What is the anglebetween MSP and petrous pyramids for the Dolichocephalic skull?
40 degrees
What is the angle between MSP and petrous pyramids for the Brachycephalic skull?
54 degrees
How do you find the cephalic index?
Cephalic Index = Width (parietal eminences) ÷ Length (frontal eminence to inion) X 100
What would a CI=75 to 80 indicate?
Mesocephalic skull type
What would a CI<75
indicate?
Dolichocephalic skull
What would a CI>80 indicate?
Brachycephalic skull
What is the widest part of the skull?
The Parietal eminences
What is the skull type?
Mesocephalic skull
Label 1-8:
- Glabella
- Nasion
- Acanthion
- Mental point
- Supraorbital groove
- Supercilliary ridge
- Interpuplillary line
- Angle
Label 1-4
- TEA
- Auricle
- Tragus
- Mental point
What is the Outer canthus?
The interpupillary line
Label 1-5
- SOM
- Midlateral orbital margin
- IOM
- Outer canthus
- Inner canthus
What is used to asses rotation when positioning a patient’s skull?
The outer canthus of the eye
What is the point between the outer canthus and the EAM?
Orbital meatal line
What is the landmark for the top of the petrous ridges?
TEA
What is the AML?
Acantiomeatal line
What is the LML?
The lips-meatal line
What is the MML?
The mentomeatal line
What is the GML?
The glabellomeatal line
What is the OML?
The orbitomeatal line
What is the IOML/reid’s baseline?
The infraorbitomeatal line
How many degrees difference is there between the GML and OML?
8 degree difference
How many degrees difference is there between the OML and IOML?
7 degree difference
Label these lines:
Red: OML/RBL
Green: GML
Blue: IOML
What is the best Radiation Protection for the skull?
Gonadal sheilding and positioning PA
In which direction does an asthenic patients head tilt during a lateral against the IR?
Tilts upwards
In which way does a hypersthenic patients head tilt in a lateral against the IR?
Tilts downwards
Where should the hair be when imaging the skull?
The hair should be left down and tucked behind the ear.
What artificats are necessary to remove from the patient prior to skull imaging?
Remove necklace, earrings, piercings, GLASSES
What should be seen in a lateral skull?
- Orbital plates are superimposed
- TM Joints (mandibular condyles) are in the same vertical plane
- EAMs’ are in the same vertical plane
- Sella Turcica is in profile
What indicates that there is tilt in a lateral skull?
-Orbital plates will not be superimposed
What indicates that there is rotation in a lateral skull?
-MSP is not parallel to IR or bucky
-TM joints or mandibular condyles will not be superimposed posteriorly
-EAMs’ will not be in the same vertical plane
What are the red, orange and yellow lines indicating?
Red: Condyles of the mandible superimposed
Orange: Cribriform plate
Yellow: Greater wings of sphenoid
What does the greater wing of sphenoid form?
Forms the anterior wall of the middle cranial fossa
What are the positioning faults made in this image?
-Top of head is not flat (needs to lift the chin up)
-Tilt (orbital plates are not superimposed, and condyle is lower), vertex is tilted to the left
-Rotation (Nose is rotated towards the left)
Which way is the patient tilted and rotated?
Nose is rotated to the left and vertex is tilted to the right
What position of the skull best demonstrates the IAC’s?
The PA Projection – Ruggles Method
Where must the top of the petrous ridges be in a PA ruggles method?
Must be at the top of the orbits
What nerve passes through the IAC?
Vestibular cochlear nerve 8
Where must the petrous ridges be in a PA ruggles?
Petrous ridges must fill orbits
What position best demonstrates the superior orbital fissures?
PA Axial Projection – Caldwell Method
If we did the Caldwell Method AP, what positioning changes would need to be made?
We would put the OML perpendicular to the bucky, and angle 15 degree cephalad
Where will the petrous ridges be in a Caldwell method?
Petrous ridges in lower third of orbits
If the CR is a 0 degrees, where will the petrous ridges be?
0=petrous ridges at the top of the orbits
If the angle is a 15 degrees caudad, where will the petrous ridges be?
15 degree=petrous ridges at the lower 1/3
What are the different coloured lines indicating?
Red: Orbits
Blue: BOS
Yellow: petrous ridges (in the lower 1/3)
Green: Superior orbital fissures
What method is this?
PA axial Caldwell
Which way is the patient rotated and tilted?
-Rotated nose to the left
-Tilted vertex to the right
Critique this image for the PA axial caldwell:
-Vertex tilted toward the right
-Hair tie left in
-Nose is rotated towards the left
-FOV is too large
-Petrous ridges in the middle of the orbit (5 degrees caudad needed)
-Marker not flipped
Approximetly what incorrect angle was used on this patient?
Patient is a AP (Caldwell)
20 degrees cephalad
Aproximetly what incorrect angle was used on this patient?
Patient is PA, caldwell
10 degrees caudad
What angle is required if the IOML was perpendicular when doing the AP Axial Projection- Towne Method skull?
37 degrees
What should be demonstrated within the foramen magnum in the AP Axial Projection- Towne Method skull?
Dorsum sellae and posterior clinoid processes demonstrated within the foramen magnum
Label 1-6
- Parietal bone
- Occipital bone
- Foramen magnum
- Petrous ridge
- Posterior clinoid process
- Dorsum sella
What is being shown in red?
Dorsum sella
Label 1-5 in this poorly positioned patient:
- Occipital bone
- Foramen magnum
- Petrous ridge
- Posterior arch of C1
- Mandibular condyle
What should be seen on a Submentovertical Projection (SMV) Basal View or Schuller Method
-Odontoid process is demonstrated within the foramen magnum
-Equal distance between mandibular condyles and edges of skull
-Mandibular condyles anterior to petrous ridges
-Mental protuberance superimposed on frontal bone
What method is this?
Submentovertical Projection (SMV) Basal View or Schuller Method
Critique this SMV image:
-Mandible tilted to the left
-Mandibular condyles should be anterior to petrous ridges
-Mandible should be lifted high/extended neck
Critique this SMV image:
-Needs more extension of the neck
-Nose rotated to the right
-Clipping bottom part of skull
What does the lateral skull demonstrate?
The entire cranium
What does the Towne method demonstrate?
The occipitobasal region of skull
What does the Ruggles method demonstrate?
The frontal bone and the IACs within the orbits
What does the Caldwell method demonstrate?
The frontal bone
What does the Schuller method Basal view demonstrate?
The base of skull
