Skull bones part 1

How many cranium bones?

8 Bones

-Frontal

-2 Parietal

-2 Temporal

-Occipital

-Sphenoid

-Ethmoid

Skull Cap

• Frontal Bone

• Occipital Bone

• Right Parietal Bone

• Left Parietal Bone

Skull Floor

• Sphenoid Bone
• Ethmoid Bone
• Right Temporal Bone
• Left Temporal Bone

1. Ethmoid

2. Frontal

3. Parietal

4. Occipital

5. Temporal

6. Sphenoid (left greater wing)

1. Frontal

2. Ethmoid

3. Sphenoid

4. Temporal

5. Parietal

6. Occipital

What bone is it?

Label

Frontal bone

1. Glabella - between eyebrows

2. Supercilliary ridge(arch) - eyebrows

3. Supraorbital margin (SOM) - below eyebrow

4. Frintal tuberosity (eminence)

5. Supraorbital groove - above eyebrows

6. Supraorbital notch (foramen) - for blood vessels and nerves, on margin

What bone is it?

Label

Frontal bone - orbital view

1. Nasal (frontal) spine

2. Ethmoid notch

3. Orbital plate

What bone is it?

Label

Parietal bones

1. Right parietal bone

2. Parietal tubercle (eminence)

3. Left parietal bone

What bone is it?

Label

Occipital bone

1. Lateral condylar portion (occipital condyle) = forms atlanto-occipital joint C1

2. Foramen magnum

3. Squamous portion

4. External occipital protuberance = inion

What bone is it?

Label

Ethmoid bone

1. Crista galli → goes up through ethmoid notch

2. Cribriform plate

3. 2 Lateral labyrinth (mass)

4. Perpendicular plate

5. Superior nasal concha

6. Middle nasal concha (turbinate)

What bone is it?

Label

Sphenoid bone - anchors bones

1. Anterior clinoid process

2. Foramen rotundum

3. Foramen ovale

4. Foramen spinosum

5. Clivus

6. Lesser wing

7. Greater wing

8. Sella turcica

9. Dorsum sellae

What bone is it?

Label

Sphenoid bone - oblique view

1. Superior orbital fissure

2. Foramen rotundum

3. Foramen ovale

4. Lateral pterygoid process (plate)

5. Pterygoid hamulus

6. Medial pterygoid process (plate)

7. Dorsum sellae

8. Optic foramen

What bone is it?

Label

Sphenoid bone - lateral view

1. Anterior clinoid processes

2. Posterior clinoid processes

3. Dorsum sellae

4. Clivus

5. Sella turcica - in profile when lateral

What bone is it?

Label

Temporal bones - Superior view

1. Petrous ridge

2. Petroud pyramid

3. Internal acoustic meatus

4. EAM

5. Jugular foramen

What bone is it?

Label

Temporal bones - lateral view

1. Zygomatic arch

2. Temporomandibular fossa

3. Styloid process

4. EAM

5. Mastoid process (tip)

6. Mastoid portion

Label the 3 parts

1. Squamous portion

2. Mastoid portion

3. Petrous portion

Temporal bones

Mesocephalic skull

• Average skull

• Measurement from frontal - occipital bone= 19 cm = length

• Measurement from parietal eminence- parietal eminence = 15 cm = width

• Width is 75-85% of length

• Petrous pyramids = form a 47 degree angle to MSP

Dolichocephalic

• Width is less than 75% of length

• Petrous pyramind = form a 40 degree angle to MSP (-7)

• Oval skull

Brachycephalic

-Rounded skull

-Width is 80% or more of length

-Petrous pyramids= form a 54 degree angle to MSP (+7)

1. Glabella

2. Nasion

3. Acanthion

4. Mental point

5. MSP

6. Supraorbital groove(SOG)

7. Superciliary ridge (arch)

8. Interpupillary line

9. Angle (gonion)

1. Glabella

2. Nasion

3. Acanthion

4. Mentum/mental point

5. Gonion (angle of mandible)

6. Top of ear attachment(TEA)- petrous ridges

Orbital landmarks

1. SOM- Supraorbital margin

2. Midlateral orbital margin

3. IOM - Infraorbital margin

4. Outer canthus

5. Inner canthus

Facial landmarks

-Know in order from highest to lowest

GML - Glabellomental

OML- Orbitomeatal

IOML- Infraorbitomeatal, 7 degrees from OML

AML- Acanthiomeatal

LML-Lipmeatal

MML-Mentomeatal

POSITIONING AND TECHNICAL CONSIDERATIONS

Erect vs. recumbent
• kV range: 70-85
• Minimum 40 inches (102 cm) SID
• Small focal spot
• Shielding of radiosensitive organs
• 10 X 12 IR with collimation

Remove-

Jewelry
False teeth
Hearing aide
Eye Glasses
Hair ties/clips

Wigs
Extentions

PA SKULL

Frontal Bone
OML perpendicular on PA/AP
• Options:

• TRUE PA- CR 0° exit at glabella →Petrous pyramids fill the orbits

• CALDWELL- CR 15° caudad exit at nasion→Petrous Ridges in lower 1/3 of orbit

TOWNES METHOD

AP AXIAL PROJECTION

Occipital Bone
• Caudal angle- downtown

• Preferred OML / CR 30 degrees

• Settle for IOML / CR 37 degrees

• CR is 2 ½ inches above glabella

Foramen magnum with dorsum sellae in center

HAAS

PA AXIAL PROJECTION

Occipital Bone
Reverse of Townes except:
• Angle 25 degrees cephalic
• Dorsum sellae appears larger within foramen magnum
• Magnification of occipital bone evident
• Exit 1 ½ inch above Nasion

LATERAL SKULL

Need true lateral position of head
• Perform both Right & Left to see temporal and parietal bones
• Three lines:

• MSP - parallel

• PL –perpendicular to IR

• IOML perpendicular to front edge of IR

-CR 2” superior to EAM
• Errors: Rotation, Tilt, Excessive neck flexion, Excessive neck extension

ROTATION

Rotation= Anterior to Posterior separation
• Mandibular rami
• EAM
• Greater wings of sphenoid

TILT AND THE MSP

Inferior to Superior separation
• Orbital plates
• Lesser wings of sphenoid