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Corresponds to the level of the Petrous Ridge

Supraorbital Groove

Corresponds to the highest level of the facial bones

Interpupillary Line

A line used in positioning to ensure that the skull is in a true lateral position


Posterior angle of the jaw


The small cartilaginous flap covering the EAM

Outer Canthus

Lateral junction of the eye

Orbitomeatal Line

Line between the mid-lateral orbital margin and the EAM

Glabelloaveolar Line

Line between the glabella and aveolar process of the mandible

Infraorbitomeatal Line

Line between the inferior orbital rim and the EAM

Mentomeatal Line

Line between the mental point and EAM


Smooth, slightly raised area between the eyebrows


The most prominent point of the external occipital protuberance


A depression at the bridge of the nose

Parietal Eminence

Distance between these two points would indicate the widest dimension of the skull

Mastoid Tip

This point can also be used in positioning fr he open-mouth C-spine

Erosion is best demonstrated on which projection?

Lateral Projection

Anatomical Landmarks used to evaluate the Lateral Projection

Orbital Lines or Roof
Rami Mandible
Body of Mandible
Anterior/Posterior Clinoids
Petrous Pyramids
Greater/Lesser Wing of Sphenoid
Mastoid Tip

Base of Skull, Mastoid Tip, Occlusal Plane

Perpendicular to the film for the AP Open Mouth C-Spine Projection

CR for routine Caldwell Projection

15 degrees Caudal

Why the sinus x-ray is erect

Air and Fluid Levels


Skull angle of 54 degrees between the midsagital plane and long axis of the petrous bone


Skull angle of 47 degrees between the midsagital plane and long axis of the pertrous bone


Average size Skull

Reids Baseline is also called

IOML or Anthropalogic Baseline

Lateral Skull Potioning, Which baseline is perpendicular to the imaginary line along the front edge ofthe IR

IOML is Perpendicular to Imaginary Line

What Projection and CR angle to demonstrate the Superior Orbital Fissure?

Caldwell, 30 degrees Caudal

Which Baseline is parallel to IR for the Submentovertex Projection (SMV)

IOML is Parallel to IR, Perpendicular to CR

CR and Angle for the Haas Method

25 degrees Cephalad

Petrous Pyramid

Densest bone of the 3 aspects of the temporal bone

Properly positioned AP Axial (Towne) projection should place the dorsum sellae in the middle of?

Foramen Magnum

Lack of symmetry of the Petrous Ridges indcates what problem with a Radiograph of an AP Axia Projection?


What Positioning errr is present if te Mandibular Rami are not superimposed on a Lateral Skull Radiograph?


With a traum patient, what must b determined before performing the SMV Projection?

C-Spine Injury

Where should the Petrous Ridges be located on well positioned 15 Degree Caldwell?

Lower 1/3 of the Orbit

Where should the Petrous Ridges be located on well positioned 30 Degree Caldwell?

Lower than the lower 1/3 of the Orbit

What Skull projection results in th highest Thyroid Dose

SMV (264 mR)

CR and Patient Position for the Towne Projection ofthe Skull

2 1/2" superior to the Glabella, 30 degrees Caudal to the OML

CR and Patient Position for the Lateral Skull Projection

2" Superior to the EAM, Perpendicular to the IR

CR and Patient Position for the Caldwell Projection of the Skull

PA, OML& MSP Perpendicular to the IR, 15 degrees Caudal exiting the Naison

Routine Skull Series


Structures best demonstrated on the Towne Projection

Dorsum Sellae within the Foramen Magnum

Structures best demonstrated on the Lateral Projection

Sellae Turcica in Profile, Cranial halves, Orbital Plates, Clinoids ad Rami Superimposed

Structures best demonstrated on the Caldwell Projection

Petrous Pyramids in the lower 1/3 of the Orbit

Special Skull Projections

PA or AP Skull
Haas (Reverse Towne)

Haas (Reverse Town) Special Projection Patient Position and CR

PA, OML Perpendicular to the IR, 25 Degree Cephalad, Occipital Bone is Magnified

Caldwell Special Projection Patient Position and CR

PA, OML & MSP perpendicular to IR, 30 degrees Caudal,
Superior Orbital Fissure, Foramen Rotundum, Inferior Orbital Rim

SMV Special Projection Patient position and CR

Vertex of head on IR, IOML Parallel to IR, CR 3/4" Anterior to EAM & Perpendicular to IOML
Petrous Pyramids posterior to mandibular condyles, Sphenoid & Ethmoid Sinuses, Foramen Ovali & Foramen Spinosum

Difference in Degrees between the infraorbitomeatal & orbitomeatal lines

7-8 degrees

Small Irregular Bones occassionally found in the Sutures


Bone that contains the Cribiform Plate


Bone that contains the Foramen Ovale


Bone assciated with and protects the Hypophysis Gland


Cranial Bone that Articulates with all other Cranial Bones


Widest portion of the cranium is formed at a level of?

Parital Tubercles

Lateral Juntion of eyelid

Outer Canthus

Posterior Angle of Jaw


Corresponds to the highest (Nuchal) Line ofthe Occipital Bone


Located at junction of the 2 Nasal Bones & the Frontal Bone


Line between the Midlateral Orbital Margin & the EAM


Center Point of the EAM

Auricular Point

Positioning line that is primarily used for the modified Waters Projection

Lips-Meatal Line

Line used in positioning to ensure that the skull is in a true lateral position

Interpupillary line

Average KV for the Skull

Film 65-80 Kv
Digital 70-80 Kv

AP Axial (Towne) Skull results in about 10x's more dose to __________ than in a PA Axial (Haas) Projection.


# of Cranium Bones


# of Facial Bones


4 Cranial Bones that form the Calvaria (Skull) Cap

Right & Left Parietal

4 Cranial Bones that form the Floor of the Cranium

Right & Left Temporal

Small Horizontal Plate of the Ethmoid

Cribiform Plate

Vertical Plate of the Ethmoid Bone forming the Upper Portion of the Bony Nasal Septum

Perpendicular Plate

Structure found in the middle of the Sphenoid Bone that surrounds the Pituitary Gland

Sella Turcica

Posterior Aspect of the Sella Turcica

Dorsum Sellae

Which structure of the Sphenoid allows for the passage of the Optic Nerve & is the actual opening into th orbit

Optic Foramen

Which Structure of te Sphenoid Bone help form part of the Lateral Walls of the Nasal Cavities

Medial & Lateral Pterygoid Processes

Radiograph best demonstrates the Sella Turcica


Aspect of Frontal Bone forms the Superior aspect of the Orbit

Orbital or Horizontal Portion

Cranial Surtures are________joints

Fiborous or Synarthrodial

Small irregular bones that sometimes develop in adult skull sutures are_________&__________bones & are most frequently found in the________suture.

Sutural & Wormian Bones, Lambdoidal Suture

Superior Rim of Orbit

SOM (Supraorbital Margin)

Notch that separates the Orbital Plates from eachother

Ethmoid Notch

Cranial Bones form the Upper Lateral Walls of the Calvarium

R & L Parietals

Cranial Bone Contains the Foramen Magnum


Small Prominence located on Squamous Portion of the Occipital Bone

External Occipital Protuberance or Inion

3 Aspects of Temporal Bones

Squamous Portion
Mastoid Portion
Petrous Portion

Opening of Temporal Bone serves as a Passageway for nerves of Hearing & Equilibrium

Internal Acoustic Meatus

Width between 75% & 80% of Length


Width 80% or more Length


Width less than 75% of length


CR Angles & Degree of Rotation stated for basic skull positions are based on the ___________Skull & has a angle of _________degrees between the Midsagital Plane & long axis of the Petrous Bone.

Mesocephalic, 47 degrees

Long, Narrow Skull has an angle of appx ______degrees between the midsagital plane & the long axis of the Petrous Bone

+/- 40 Degrees

Thyroid Dose for SMV projection of skull

200-300 mRad

5 Most Common Errors made during a Skull Radiograph

Excessive Flexion
Excessive Extension
Incorrect CR Angle

What patients require a 25% - 30% reduction in mAs during skull projections

Adults w/ Osteoporosis

Most common neuroimaging procedure performed for the cranium is done w/ what imaging modality


Imaging modality used on neonates w/ a possible intracranial hemorrhage


Imaging Modality performed to evaluate patients for Alzheimer disease


Basal Skull Fracture

May produce air-fluid level in Sphenoid Sinus

Osteolytic Neoplasm

Destructive Lesion w/ irregular margins

Depressed Skull Fracture

Ping Pong Fracture

Osteoblastic Neoplasm

Proliferative bony lesion of increased density

Pituitary Adenoma

Tumor that may produce erosion of the Sella Turcica

Multiple Myeloma

Bone tumor that originates in bone marrow

Pagents Disease

Osteitis Deformans
May require increase in manual exposure factors

Which Cranial Bone is best demonstrated w/ an AP Axial (Towne Method) projection of the skull

Occipital Bone

When using a 30 degre caudad angle for AP Axial (Towne) projection of skull, what positioning line should be perpendicular to the IR


Lack of Symmetry of the Petrous Ridges indicates what problem?


If patient can't flex head for AP Axial (Towne), what should Tech do?

IOML perpendicular to IR 37 degrees Caudal

What evidence on AP Axial (Towne) indicates correct CR Angle & Correct Head Flexion

Dorsum Sellae & Posterior Clinoids visualized in Foramen Magnum

What positioning error if the Mandibular Rami are not superimposed on a Lateral Skull


Projection where Frontal Bone has little or no distortion

PA 0 degree CR

CR for Lateral of Sella Turcica

3/4" Anterior & 3/4" Superior to EAM

Which Imaging Modality is Best to Differentiate between an Epidural & Subdural Hemorrhage


Projection Best Demonstrates Sella Turcica in Profile


Projection Best Demonstrates Foramen Rotundum in profile

25-30 degree PA Axial

Projection Best Demonstrates Clivus in profile


Where does the CR exit for a PA Axial (Haas) of Skull

1 1/2" Superior to the Naison

CR Angle for the AP Axial (Sella Turcica) if Dorsum Sellae & Posterior Clinoid Processes are Primary Interest

37 degree Caudad



Cranial Suture formed by inferior junction of the parietals to the temporal bone

Squamosal Surture

Shallow depression Posterior to Base of Dorsum Sellae & Anterior to Foramen Magnum


Pituitary Gland

Hypophysis Cerebri
Master Gland

Suture Separates Frontal Bone from 2 Parietals

Coronal Surture

CR for AP Axial (Towne) w/ IOML Perpendicular to IR

37 Degrees Caudad to IOML
30 Degrees Caudad to OML

2 Projections show Dorsum Sellae within Foramen Magnum

AP Axial (Towne) 30 Degrees Cephalic OML
PA Axial (Haas) 25 Degrees Cephalic OML

Large Cartilanginous aspect of External Ear

Auricle or Pinna

Region where surtures join in the infant skull, soft spots

Anterior/Posterior Fontanels

Articulation @ Anterior end of Sagittal Surture



located between outer canthus & EAM


Connects infraorbital Margin to EAM


Connects Glabella to point Anterior Aspect of Alveolar process of Maxilla


Line between Glabella & Eam


Under Nose to EAM


Lips to EAM


Mental Point (Chin) to EAM


Connects Pupils or Outer Canthi of Eye


Opening of external ear canal


Superior attachment of the auricle where frames of eye glasses rest

Rotation for Lateral Skull Positioning

Greater Wing of Sphenoid
Petrous Pyramid
Mastoid Tip
(Left or Right Turn)

Tilt for Lateral Skull Positioning

Orbital Roof (Plate, Fontal Lines)
Body of Mandible
Lesser Wing of Sphenoid
Mastoid Tip
(Chin up or don)


IOML Perpendicular to Imaginary Plane at Front Edge of IR
(Chin up or down)

RHESE Method Shows

Optic Foramen

3 Major Foramen Opening


What is the best modalities used today to see the Erosion of the Sella Turcica


Crista Galli

Holds Coverings of the Brain together

Junction Points

Asterion - Side
Bregma - Front
Lambda - Back
Pterion - Side


Coronal - Front
Lambdoidal - Back
Squamosal - Side
Sagittal - Middle


MSP (Mid sagittal Plane)

Facial Landmarks

Mental Point
Supercilliary Arch

Lateral Landmarks

Auricle (Pinna)
Gonion (Angle)

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