1Normal Radiographic Anatomy of the Skull(and you thought the SPINE was complicated)Laura E. Ziegler, DVMT. Murakami, DVMSkull Anatomy• Anatomy is very complex• Skull radiography is performed relatively infrequently, so is unfamiliar• Knowledge of anatomy is essential• Breed variation exists• Individual variation existsSkull Anatomy• Proper positioning is VITAL– Obliquity will distort normal structures– Obliquity may allow you to see normal structures that are not normally seen• Exposure factors are often high• General anesthesia is mandatory in all but the simplest clinical questions (where did that fishhook go?)2Skull Anatomy• Multiple views are almost always necessary• Type of view(s) selected will depend on clinical question to be answered• Because of anesthesia, multiple views, and technician time, skull radiographs are fairly expensive• Because of the complexity of anatomy and similar appearance of various pathology, findings are often very non-specificSkull Anatomy• STRONG CONSIDERATION SHOULD BE GIVEN TO USING CT SCAN OR MRI AS THE PRIMARY MEANS OF IMAGING THE SKULL• CT/MRI is somewhat more expensive, and certainly less available, but provides MUCH more thorough and clear informationLateral ViewUse to evaluate:– Cranium– Mandible (SUPERIMPOSED)– Nasal cavity and sinuses (SUPERIMPOSED)– Maxilla (SUPERIMPOSED)– Hard palate3Lateral View• Should be able to identify:– Hard palate– Soft palate– Nasopharynx– Oropharynx– stylohyoid, epihyoid, ceratohyoid, basihyoid, and thyrohyoid bonesLateral View4Lateral View• Should be able to identify:– Nasal conchae (turbinates)– Ethmoid conchae (turbinates)– Frontal sinus– Zygomatic arch– Osseous tentorium– Petrous temporal boneLateral ViewLateral View• Should be able to identify:– Cribiform plate– Tympanic bullae– External occipital protuberance– Occipital condyles and AO joint– Mandible• Mental foramen• Body and ramus• Coronoid, condyloid, and angular processes5Lateral ViewDorsoventral ViewUse to evaluate:– cranium– mandible– TMJ– tympanic bullae– external ear canals– NOT very useful for nasal cavity6Dorsoventral View• Should be able to identify:– Mandible• Body• Coronoid, condyloid, and angular processes– Temporomandibular joint (TMJ) – Zygomatic arch– Tympanic bullae– External ear canalsDorsoventral View• Should be able to identify:– Vomer/osseous nasal septum– Cribiform plate– Nasal and ethmoid turbinates– Frontal sinuses (maybe)– Occipital condyles and AO joint– Dental structures• Enamel, pulp canal, periodontal ligament, lamina denta7Open-mouth VD ViewUse to evaluate:– nasal cavity– maxilla8Open-mouth VD View• Should be able to identify:– Everything seen on DV view in the rostral skull (about from cribiform plate on)– Palatine fissures– Advantage is absence of superimposition of the mandible and tongue– Disadvantage is mild distortion (beam not perpendicular to film)Intraoral Views • Can use for assessment of maxilla/nasal structures (DV intraoral)• Can also use to assess mandible (VD intraoral)• Provides higher detail, but more limited view• “dental radiographs” are a subset of intraoral9Intraoral ViewsLateral Oblique ViewUse to evaluate:– maxilla– mandible– TMJ– tympanic bullae– dental arcades– frontal sinuses and frontal bones101112Frontal ViewUse to evaluate:– Frontal sinuses– Frontal bones– Other structures are too distorted and superimposed to be useful– Should collimate other structures out of the image13Basilar ViewUse to evaluate:– TMJ– Tympanic bullae– Dens (safe?)– Again, other structures not really helpful, collimate as much as practical1415Lateral View Effect of AgeEffect of Age16Effect of AgeEffect of