Skull Radiographic Views & Anatomy

Question 1

What are skull radiographs?

Answer 1

group of plain radiographs used primarily for assessing maxillofacial trauma

Question 2

What are the 4 main types of skull radiograph?

Answer 2

• occipitomental
• posterior-anterior mandible
• reverse Townes
• true lateral skull

Question 3

What are occipitomental radiographs used for?

Answer 3

primarily for fractures of the mandible

Question 4

What are posters-anterior mandible radiographs used for?

Answer 4

• fractures of the posterior mandible
  
  • excluding condyles

Question 5

What are reverse Towne’s radiographs used for?

Answer 5

primarily for fractures of the mandibular condyles

Question 6

What equipment is required to take skull radiographs?

Answer 6

• x-ray equipment
  
  • specialised skull unit
  • can position patient
    
    • standing up
    • lying on back
  • capture different angles
• receptor
  
  • digital
  • large to capture relevant areas

Question 7

What is the orbitomeatal line?

Answer 7

outer canthus of eye to centre of external auditory meatus

Question 8

What reference line is used for most skull radiographs?

Answer 8

• orbitomeatal line

Question 9

What do occipitomental radiograms show?

Answer 9

show the facial skeleton, avoiding superimposition of the skull base

Question 10

What angles can occipitomental radiographs be taken at?

Answer 10

• 0 degrees
• 10 degrees
• 30 degrees
• 40 degrees
• tend to use two different degree views
  
  • 10 and 40 degrees
  • may be referred to as Waters view

Question 11

What are the indications for taking occipitomental radiographs?

Answer 11

• middle third fractures
  
  • Le Fort I, II and III
  • zygomatic complex
  • naso-ethmoidal complex
  • orbital blow out
• coronoid process fractures

Question 12

How should a patient be positioned for an occipitomental radiograph?

Answer 12

• face towards receptor
• head tipped back
  
  • orbitomeatal like at 45 degrees
    
    • to receptor and floor
  • ‘nose to chin position’
• x-ray beam
  
  • angled depending on type taken
  • 0 degrees
    
    • perpendicular to receptor
    • centres through occiput
  • 30 degrees
    
    • 30 degrees above perpendicular
    • centred through lower border orbit

Question 13

What are the most important pieces of anatomy to look at on an occipitomental radiograph?

Answer 13

• zygomatic bone and zygomatic arch
  
  • temporal bone
• orbital rim
• infra-orbital foramen
• maxillary sinus
• coronoid process

Question 14

What does a poster-anterior mandible radiograph show?

Answer 14

• shows posterior parts of the mandible
• not suitable for facial skeleton
  • superimposition
    
    • skull base
    • nasal bones
    • vertebrae

Question 15

What are the indications for a postero-anterior mandible radiograph?

Answer 15

• lesions and fractures
  
  • posterior third of body
  • angles
  • rami
  • low condylar necks
  • medio-lateral expansion of lesion
• mandibular hypoplasia/hyperplasia
• maxillofacial deformities

Question 16

How should a patient be positioned for a poster-anterior mandibular radiograph?

Answer 16

• face towards the receptor
• head tipped forward
  
  • orbitomeatal line
    
    • perpendicular to receptor
    • forehead-nose position
• x-ray beam
  
  • perpendicular to receptor
  • centred through cervical spine
    
    • level of rami

Question 17

Why is the x-ray beam projected from the posterior aspect for skull x-rays?

Answer 17

• reduced magnification of face
  
  • less distortion of relevant structures
  • back of skull magnified
    
    • less important
• reduced effective dose
  
  • x-ray beam partly attenuated
    
    • by back of skull
    • before reaching face
  • lower radiation to radiosensitive tissues
    
    • lens of eye

Question 18

What are the most important pieces of the anatomy to look at on a poster-anterior mandible radiograph?

Answer 18

• posterior mandible

Question 19

What does a reverse Townes radiograph show?

Answer 19

• shows the condylar heads and neck
• similar to poster-anterior mandible
  • different x-ray beam angle
  • mouth open
    
    • drop the condylar heads
    • move out of the glenoid fossae

Question 20

What are the indications for a reverse Townes radiograph?

Answer 20

• high fractures of the condylar necks
• intra-capsular fractures of TMJ
• condylar hypoplasia/hyperplasia

Question 21

How should a patient be positioned for a reverse Townes radiograph?

Answer 21

• face towards receptor
• head tipped forward
  
  • orbitomeatal line perpendicular
    
    • to receptor
    • forehead-nose position
• mouth open
  
  • moves condylar heads
  • out of glenoid fossae
• x-ray beam
  
  • 30 degrees below perpendicular line
    
    • to receptor
  • centres through condyles

Question 22

What are the most important pieces of anatomy to look for on a reverse Townes radiograph?

Answer 22

the condyles