1. And Their Radiographic Appearance
BONES
And Their Radiographic Appearance

2. 22 Bones make up the skull Cranial bones include: Occipital (one)
Frontal (one)
Parietal (two)
Temporal (two)
Sphenoid (one)
Ethmoid (one)
Cranial bones surround the brain

3. The Skull Bones:
1 - mandible 2 - maxilla 3 - zygomatic 4 - nasal bone 5 - frontal bone 6 - sphenoid bone 7 - temporal 8 - occipital bone 9 - lacrimal bone ethmoid bone parietal bone

4. Facial bones include:
Mandible (one)
Maxilla (two)
Zygomatic (two)
Lacrimal (two)
Nasal (two)
Inferior nasal conchal (two)
Vomer (one)

5. Terms that describe bone anatomy
Process – general term for any prominence
Fossa - depression on the surface of the bone
Suture – where two bones join
Tuberosity – bony prominance, usually where muscle attaches, ie maxillary tuberosity
suture
Mastoid process
Temporal fossa

6. Terms that describe bone anatomy
Notch – indentation on the edge of a bone
Ridge – elongated prominence
Foramen - opening
Mental foramen
External oblique ridge
Mandibular notch

7. Two types of Bone – compact and cancellous
Cancellous bone (also called spongy bone) makes up center of bones
Contains bone marrow spaces (called “trabeculation” on radiographs)
More radiolucent than compact bone
trabeculation

8. Compact Bone
Compact bone- forms plates that form outside of bones, linings for alveolus, foramina, etc…
Is more radiopaque because of its density
Compact bone
Cancellous bone

9. Compact Bone Lines Alveolus (socket)
It is also called (*and means same thing):
Lamina dura (on radiographs only)
Cribriform plate
Cortical bone
Alveolar bone proper

10. Compact bone outlines alveolar crest (when no bone has been lost due to periodontal disease!)
Alveolar crest (radiopaque)
Periodontal ligament space (radiolucent lining)
Lamina dura (radiopaque lining)

11. Do you see any compact bone outlining the alveolar crest?

12. Lateral View Identification
Mandible
Maxilla
Zygomatic arch
Condyle
External auditory meatus
Temporal bone

13. Lateral closeup Condyle Articular eminence Coronoid process Ramus
Articular fossa
Mandibular notch
Coronoid notch 6 7

14. Temporomandibular Joint
Articular or gleniod fossa
Articular eminance
Mandibular condyle articulates with temporal bone in the articular fossa (also called glenoid fossa, mandibular fossa)
Most anterior border of articular fossa is the articular eminance
If someone opens wide and the condyle slides anterior to the eminance, the person has “lockjaw”

15. Lateral closeup Dehiscence Fenestration Mental foramen
Zygomatic process of maxilla
Alveolar bone
Alveolar crest
External oblique ridge 7

16. Dehiscence vs Fenestration
Bony defects of unknown cause
Neither can be found radiographically, only during surgery
Fenestration, defect completely surrounded by bone
Dehiscence, alveolar crest bone absent
fenestration
dehiscence

17. Bones of the Orbit In order of appearance Frontal Zygomatic Maxillary
Palatine
Sphenoid
Lacrimal
Ethmoid

18. Nasal Cavity
Orbit
Maxillary Sinus

19. Zygomatic Arch Commonly called the “cheekbone”
Comprised of three bones, temporal, maxilla, zygoma
temporal
zygoma
maxilla
sutures

20. Zygomatic Arch Zygomatic process of temporal bone joins with temporal
process of zygoma
Maxillary process of zygoma joins with zygomatic process of maxilla
Zygomatic Arch

21. Radiographically, the zygomatic arch appears as a radiopaque horseshoe shaped structure above maxillary molars (not always seen)

22. Maxillary Sinus – an opening in the maxillary bone, acts as a filter for inhaled air
Location of the sinus
Inside of sinus with bony covering removed

23. Inverted Y Maxillary sinus meets nasal cavity in area of canine
On radiographs, wall of sinus crosses wall of nasal cavity (both are radiopaque because they are compact bone)
Result is the “inverted Y”

24. Inverted Y
Nasal cavity
Inverted Y
Maxillary sinus

25. Septa of maxillary sinus (divides cavity)
Zygomatic Arch
Floor of maxillary sinus (radiopaque)

26. Frontal View Identification
Frontal bone
Orbit
Mental protuberance

27. Skull Identification Midline suture Anterior Nasal spine Nasal septum
Infraorbital foramen
Lateral fossa
Superior nasal conchae 6

28. Anterior Radiograph Median palatal suture (radiolucent)
Noseline (cartilage)
Nasal spine (radiopaque V-shaped prominence)
Nasal conchae
Nasal septum (elongated, thicker radiopacity) 5

29. Lateral Fossa – a depression between the maxillary cuspid and incisor
Exercise – feel your lateral fossa with your finger

30. Inferior nasal conchae Nasal septum Lateral fossa
(divides nasal cavity)
Anterior Nasal spine (V-shaped)
Lateral fossa
(Radiolucency inside circle)

31. Internal Oblique ridge- (slightly inferior to external oblique ridge)
Mandibular
foramen
Mental ridge- see figure Iannucci
Lingula – a bony projection that
partially covers the mandibular foramen

32. Lingual foramen
Genial tubercles
(muscles attach here)
Submandibular fossa
(depression for submandibular
Salivary gland)

33. Coronoid process
Coronoid notch
Mandibular (sigmoid) Notch
Condyle
Ramus
External oblique ridge
Angle of the mandible

34. External oblique ridge (thicker radiopaque band)
Note: External/internal ridges often “superimposed” over each other radiographically; therefore difficult to differentiate between the two; external always superior to internal oblique ridge (mylohyoid muscle attachment); internal usually runs below roots of mandibular molars (see figure 27-41, Iannucci)

35. Internal on “inside” or lingual

36. A- external oblique ridge B- internal oblique ridge
C- submandibular fossa
D- mandibular canal A B
Hyoid bone

37. Mandibular foramen Mandibular canal Submandibular fossa
Soft tissue outline- retromolar area
Submandibular fossa
(large radiolucency
within the circle)

38. External oblique ridge
Mandibular
canal

39. Submandibular fossa

40. Nutrient canals – passageways to teeth for vessels (arrows on film),
often seen around maxillary premolars
Genial tubercles
(Radiopacities)
Lingual foramen
(radiolucency)

41. Mental Foramen
Mylohyoid ridge or internal oblique ridge (see down by roots of teeth)– actually on lingual of mandible

42. Palate Nasopalatine or Incisive foramen Median palatine suture
Anterior or Greater
palatine foramen
Posterior or Lessor
palatine foramen
Hamulus

43. Nasopalatine or Incisive
Palatal Radiographs
Median Palatal suture
Nasopalatine or Incisive
foramen

44. Sphenoid Bone A butterfly shaped cranial bone posterior to the palate
It forms part of the orbit
It’s hamulus can sometimes be seen on third molar radiograph
Some muscles of masticaton attach to Pterygoid plate
Hamulus
Lateral pterygoid plate

45. Temporal bone
A cranial bone that articulates with mandible in its articular fossa
Other landmarks include styloid process, mastoid process
Forms part of zygomatic arch
Mastoid process
Articular or glenoid fossa (where condyle sits)

46. Infratemporal Space (skull with mandible removed)
Articular or Glenoid fossa
Maxillary
tuberosity
Styloid process (can sometimes be seen on a panoral)

47. Condyle and glenoid fossa Hard palate Coronoid process
(horizontal thicker radiopaque line)

48. External oblique ridge
Maxillary tuberosity
External oblique ridge
Nasal spine
Inverted Y