Anatomy of the maxillofacial skeleton and introduction to radiological interpretation

Question 1

What can you see from the front of the skull: describe the nasal cavity from this angle (4)

Answer 1

Nasal septum
Inferior nasal concha (bumps in either nostril)
Floor of nose just above incisor apices
Undulating surface anatomy around teeth due to roots

Question 2

Describe the nasal cavity from the side

Answer 2

Bony spike of anterior nasal spine is visible

Maxilla widens posteriorly as it articulates (joins) the cheek bone (zygoma- bulk of bone called zygomatic buttress)

Question 3

What lies underneath the surface of the nasal cavity? Describe this structue

Answer 3

1. Maxillary air sinus or antrum
2. It is a large air cavity that can extend anteriorly almost to the midline and posteriorly can hollow out the body of the zygoma. Internally sinus surface has small ridges and bumps. Walls and floor of sinus are very thin in cross-section - but appear as a dense white opaque line radiographically when seen end-on

Question 4

Describe what you would see if you were to look at the skull laterally (4)

Answer 4

• Zygomatic cheek bone is bulky and prominent (can easily overly apices of upper molars on radiographs)
• Casts white U-shaped shadow with radiolucent black centre if hollowed out by sinus
• Undulating surface of maxilla esp. in region of upper roots (noticeably over canine: canine prominence)
• Tuberosity at the very back of upper molar - smooth rounded end of maxilla

Question 5

What is the mid-palatal suture?

Answer 5

It is where the right and left side of the palate meet

Question 6

What anatomical structure would you see anteriorly behind the upper anterior incisors?

Answer 6

Nasopalatine foramen - large hole

Question 7

How the anatomy is depicted geometrically depends on what 3 factors?

Answer 7

Positions of patient
Image receptor
X-ray beam

Question 8

Why may the density of the sinus shadow vary?

Answer 8

Because the shape of the sinus varies and the density of the overlying bone varies

Question 9

What is the function of the pterygoidhamulus?

Answer 9

It is a small spur of bone which supports the muscles of the soft palate

Question 10

Describe the outer surface of the mandible (7)

Answer 10

• Chin/mental prominence
• Body
• Little holes in the body (on right and left) = mental foramen/foramina
• External oblique ridge (dense bony prominence)
• The angle
• Coronoid process
• Ascending rami/ramus

Question 11

Describe the inner surface aspect of the mandible (5)

Answer 11

• Genial tubercles (bony spurs where some muscles of tongue and neck attach)
• Lingual pit (little hole behind lower anteriors)
• Mylohyoid ridge (prominent and dense where mylohyoid muscle attaches to form floor of the mouth)

From directly underneath mandible:

• mylohyoid ridge clearly shown (thickened bone)
• Submandibular fossa (indentations)

Question 12

How can you obtain an extraoral view of the jaws?

Answer 12

By using the oblique lateral technique

Image receptor placed outside of the mouth and against side of the face - results in larger radiographs and show anatomical structures in both jaws

Question 13

What may you see on lower radiographs that are often referred to as the ‘tramlines’?

Answer 13

The inferior dental nerve inside the inferior dental canal - the edges of the canal appear as thin white opaque lines

Question 14

Why does the spinal shadow appear on either side of he image when there is only 1 spine?

Answer 14

Because the shadows are superimposed on top of each other - it is split and then stretched to the outer edges of the image.