and their radiographic appearance
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And Their Radiographic Appearance
BONES
22 Bones make up the skullCranial bones include:• Occipital (one)• Frontal (one)• Parietal (two)• Temporal (two)• Sphenoid (one)• Ethmoid (one)
Cranial bones surround the brain
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
10 - ethmoid bone 11 - parietal bone
Facial bones include:• Mandible (one)• Maxilla (two)• Zygomatic (two)• Lacrimal (two)• Nasal (two)• Inferior nasal conchal
(two)• Vomer (one)
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
Mastoid processTemporal fossasuture
Terms that describe bone anatomy
• Notch – indentation on the edge of a bone
• Ridge – elongated prominence
• Foramen - opening
Mental foramenExternal oblique ridge
Mandibular notch
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
Compact Bone
1. Compact bone- forms plates that form outside of bones, linings for alveolus, foramina, etc…
2. Is more radiopaque because of its density
Compact bone Cancellous bone
Compact Bone Lines Alveolus (socket)
It is also called (*and means same thing):
1. Lamina dura (on radiographs only)
2. Cribriform plate3. Cortical bone4. Alveolar bone proper
Lamina dura(radiopaque lining)
Periodontal ligament space(radiolucent lining)
Compact bone outlines alveolar crest (when no bone has been lost due to periodontal disease!)
Alveolar crest (radiopaque)
Do you see any compact bone outlining the alveolar crest?
Lateral View Identification
1. Mandible2. Maxilla3. Zygomatic arch4. Condyle5. External auditory
meatus6. Temporal bone
Lateral closeup
1. Condyle2. Articular eminence3. Coronoid process4. Ramus5. Articular fossa6. Mandibular notch7. Coronoid notch
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Temporomandibular Joint
• 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”
Articular or gleniod fossa
Articular eminance
Lateral closeup
1. Dehiscence2. Fenestration3. Mental foramen4. Zygomatic process
of maxilla5. Alveolar bone6. Alveolar crest7. External oblique
ridge
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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
dehiscencefenestration
Bones of the Orbit
In order of appearance• Frontal• Zygomatic• Maxillary• Palatine• Sphenoid• Lacrimal• Ethmoid
Maxillary Sinus
Nasal Cavity Orbit
Zygomatic Arch
• Commonly called the “cheekbone”
• Comprised of three bones, temporal, maxilla, zygoma
maxilla
zygoma
temporal
sutures
Zygomatic Arch
Maxillary process of zygoma joins with zygomatic process of maxilla
Zygomatic process of temporal bone joins with temporal process of zygoma
Zygomatic Arch
Radiographically, the zygomatic arch appears as a radiopaque horseshoe shaped structure above maxillary molars (not always seen)
Maxillary Sinus – an opening in the maxillary bone, acts as a filter for inhaled air
Location of the sinusInside of sinus with bony covering removed
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”
Inverted Y
Maxillary sinusNasal cavity Inverted Y
Floor of maxillary sinus(radiopaque)
Zygomatic ArchSepta of maxillary sinus (divides cavity)
Frontal View Identification
1. Frontal bone2. Orbit3. Mental protuberance
Skull Identification
1. Midline suture2. Anterior Nasal spine3. Nasal septum4. Infraorbital foramen5. Lateral fossa6. Superior nasal
conchae
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Anterior Radiograph
1. Median palatal suture (radiolucent)
2. Noseline (cartilage)
3. Nasal spine (radiopaque V-shaped prominence)
4. Nasal conchae5. Nasal septum (elongated,
thicker radiopacity)
5
Lateral Fossa – a depression between the maxillary cuspid and incisor
Exercise – feel your lateral fossa with your finger
Nasal septum(divides nasal cavity)
Anterior Nasal spine (V-shaped)
Lateral fossa(Radiolucency inside circle)
Inferior nasal conchae
Mandibular foramen
Internal Oblique ridge- (slightly inferior to external oblique ridge)
Lingula – a bony projection that partially covers the mandibular foramen
Mental ridge- see figure 27-56 Iannucci
Lingual foramen
Genial tubercles (muscles attach here)
Submandibular fossa (depression for submandibular Salivary gland)
Coronoid notchCoronoid process
External oblique ridge
Mandibular (sigmoid) Notch
Ramus
Condyle
Angle of the mandible
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 internaloblique ridge (mylohyoid muscle attachment); internal usually runs below roots of mandibularmolars (see figure 26-62 Haring)
Internal on “inside” or lingual
A- external oblique ridgeB- internal oblique ridgeC- submandibular fossaD- mandibular canal
B
A
Hyoid bone
Mandibular foramen
Mandibular canal
Submandibular fossa(large radiolucencywithin the circle)
Soft tissue outline- retromolar area
Mandibular canal
External oblique ridge
Submandibular fossa
Nutrient canals – passageways to teeth for vessels (arrows on film), often seen around maxillary premolars
Lingual foramen(radiolucency)
Genial tubercles(Radiopacities)
Mental Foramen
Mylohyoid ridge or internal oblique ridge(see down by roots of teeth)– actually on lingual of mandible
Nasopalatine orIncisive foramen
Palate
Anterior or Greater palatine foramen
Median palatine suture
Posterior or Lessor palatine foramen
Hamulus
Palatal Radiographs
Median Palatal sutureNasopalatine or Incisive foramen
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
Lateral pterygoid plateHamulus
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
Articular or glenoid fossa(where condyle sits)
Mastoid process
Infratemporal Space (skull with mandible removed)
Maxillarytuberosity
Styloid process (can sometimes beseen on a panoral)
Articular or Glenoid fossa
Condyleand glenoid fossa
Hard palate(horizontal thicker radiopaque line)
Coronoidprocess
Maxillary tuberosity
Inverted Y
External oblique ridge
Nasal spine
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