1. Normal Radiographic Anatomy of the Equine Head
Dr. Pack/Woodland
April 7, 2011.

2. Indications Nasal Discharge Head Trauma Facial / Neck Swelling
Sinusitis
Dental Disease
Head Trauma
Fractures
Facial / Neck Swelling
Guttural Pouch Tympany

3. Technical Considerations
Head is mobile and high off the ground
Sedation
Lowers head
Can use portable equipment
14x17 cassettes
Film holding device
Rope halter – no buckles
Rope halter – anatomy beneath the buckle can still be visualized

4. Lateral and Oblique Views
Standing or recumbent
Can visualize sinuses, teeth and skull fractures (frontal bone)
Obliques are needed to carefully assess tooth roots
Must label correctly
Can use barium as marker on skin if needed
Labeling

5. Morgan

6. Morgan

7. Morgan

8. DV/VD Used for comparison between sides
Difficult to keep head still and straight
Can throw off symmetry
Easier to do VD when patient is under general anesthesia
Maxilla is wider than the mandible

9. Morgan

10. Mass on Right side

11. Cranium Foals: dome-shaped Adult lateral view
Face lengthens with growth; accommodates teeth and expanding sinuses
Adult lateral view
Petrous temporal bones (tympanic bullae not visible)
Nuchal crest
Occipital condyles
Ethmoid turbinates
Ventral jaw in foals can be bumpy = from root of unerupted permanent cheek teeth.

12. A - Nuchal crest D - Occipital condyle B C D E F
Dyce et. al
A - Nuchal crest D - Occipital condyle
B - Coronoid process E - Ramus of mandible
C - Condylar process F - Body of mandible

13. Equine Skull A = Petrous temporal bone B = Cranium
C = Condyloid process
D = Coronoid process
E = Basioccipital
F = Epiglottis
G = Ethmoid turbinates

14. A – Choncofrontal sinus
B – Maxillary sinus
C – Condylar process of mandible
D – Guttoral pouch
E – Stylohyoid bone
F – Epiglottis
G – Maxillary 3rd Molar
H – Mandibular 2nd Premolar A C B D G E F H

15. Unlabelled

16. Equine Sinuses Frontal Dorsal, ventral and middle conchal Maxillary
Dorsal part of the skull, medial to orbit
Combines with dorsal conchal = conchofrontal
Dorsal, ventral and middle conchal
Maxillary
Rostal and caudal
Important relationship with the molar cheek teeth
Sphenopalatine
Trephination to remove cheek teeth = through frontal sinus into the caudal maxillary
The ones of clinical importance are the frontal, dorsal conchal and maxillary
Maxillary: Rostral extends into the ventral choncal
Caudal continues into the sphenopalatine
Sphenopalatine = superimposed with the vertical ramus of the mandible.

17. Caudal Maxillary Sinus
Frontal Sinus
Caudal Maxillary Sinus
Rostral Maxillary Sinus
Dyce et. al

18. Equine Sinuses Normally air-filled on radiographs
Fluid or a soft tissue mass can be seen
Air-fluid lines
Hard to tell if one or both sides are affected
Maxillary sinus
PM4, M1, M2, M3 tooth roots in sinus
Tooth root infections can easily cause sinusitis

19. Sinuses A = frontal B = dorsal conchal C = stylohyoid bone
D = maxillary sinus D

20. Sinuses A - Nasal bone B - Frontal sinus C - Dorsal conchal sinus
D - Maxillary sinus
E - Mandible

21. Post-op Tooth Repulsion

22. Guttural Pouches Ventral diverticulum of the auditory tube
Paired; lateral and medial compartments
Superimposed and air-filled on radiographs
Dorsal pharyngeal wall separates the ventral wall of the GP from the pharynx
Stylohyoid bones can be seen through the air filled GP’s
Retropharyngeal lymph nodes
Caudal to the GP
Infection can spread from LN to GP
Guttoral pouches = diverticulum of the auditory tube
Mucosal lining of the tube through a ventral slit between the medial and lateral supporting cartilages ml
Tympany and empyema

23. Guttural Pouches

24. A B
A = Petrous Temporal Bone
B = Basioccipital bone
C = Coronoid Process of the Mandible C

25. Basisphenoid / Basiocciptal Fractures
Occur primarily in young horses that flip over backward
Poll strikes against ground
Clinical signs depend upon amount of displacement
Minimal = usually recover but may have residual head tilt
Severe = cerebral hemorrhage and death
If horse can stand, death is not likely

27. MRI

29. Pharynx / Larynx Pharynx Epiglottis Larynx
Where nasopharynx and oropharynx join
Epiglottis
Dorsal to the soft palate
Larynx
Made up of many cartilages which are rarely seen and their location is approximated anatomically on the radiograph

30. Equine Teeth Herbivores = hypsodont teeth
Continuously erupt to compensate for attrition (wearing)
Grinding surface
Dental enamel is more dense than bone
Sinuses will be very overexposed
Lateral, obliques +/- VD

31. Equine Dental Formula Temporary teeth: Permanent teeth:
3-0-3 Maxillary
3-0-3 Mandibular
“Baby” teeth are shorter and smaller
Permanent teeth:
3-1-3(4)-3 Maxillary
Mandibular
Maxillary premolar 1 is wolf tooth
Canine teeth
Rudimentary and commonly fail to erupt in mares
Wolf teeth may not erupt. Upper jaw only.

32. Dyce et. al

33. Numbering Teeth Can not definitively tell which side without obliques
Make sure to call them maxillary or mandibular
Always look for wolf teeth

34. Teeth cont.
Mandibular 4th premolar
= Canine Tooth
Incisors

35. P2 P3 P4 M1 M2 M3 P2 P3 P4 M1 M3 M2

37. Tooth root fractures (maxillary molars)

38. Ruminants Horns: - Grow from frontal bones
Cornual diverticulum = continuation of frontal sinus into the cornual process

39. Dental Formula Temporary Teeth: Permanent Teeth: 0-0-3 Maxillary
3-1-3 Mandibular
Permanent Teeth:
Maxillary
Mandibular

41. Lumpy Jaw (Actinomyces bovis)

42. Lumpy Jaw = Actinomyces bovis

43. Test yourself
What structures can you correctly identify?