Normal Radiographic
Anatomy of the
Equine Head
Dr. Pack/Woodland
April 7, 2011.
Indications
• Nasal Discharge
– Sinusitis
– Dental Disease
• Head Trauma
– Fractures
• Facial / Neck Swelling
– Guttural Pouch Tympany
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
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
Morgan
Morgan
Morgan
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
Morgan
Mass on
Right side
Cranium
• Foals: dome-shaped
– 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
A
B
C
D
E
F
Dyce et. al
A - Nuchal crest
B - Coronoid process
C - Condylar process
D - Occipital condyle
E - Ramus of mandible
F - Body of mandible
Equine Skull
• A = Petrous temporal
bone
• B = Cranium
• C = Condyloid process
• D = Coronoid process
• E = Basioccipital
• F = Epiglottis
• G = Ethmoid turbinates
A – Choncofrontal
sinus
A
B – Maxillary sinus
C – Condylar
process of mandible
G
D – Guttoral pouch
E – Stylohyoid bone
G – Maxillary 3rd
H – Mandibular 2nd
Premolar
E
F
F – Epiglottis
Molar
C
B
H
D
Equine Sinuses
• Frontal
– 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
Frontal Sinus
Caudal Maxillary Sinus
Rostral Maxillary Sinus
Dyce et. al
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
Sinuses
•
•
•
•
A = frontal
B = dorsal conchal
C = stylohyoid bone
D = maxillary sinus
D
Sinuses
• A - Nasal bone
• B - Frontal sinus
• C - Dorsal conchal
sinus
• D - Maxillary sinus
• E - Mandible
Post-op
Tooth
Repulsion
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
Guttural Pouches
A
A = Petrous
Temporal Bone
B = Basioccipital
bone
C = Coronoid
Process of the
Mandible
B
C
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
Pharynx / Larynx
• Pharynx
– 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
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
Equine Dental Formula
Temporary teeth: Permanent teeth:
• 3-0-3 Maxillary
• 3-0-3 Mandibular
– “Baby” teeth are
shorter and smaller
• 3-1-3(4)-3 Maxillary
• 3-1-3-3 Mandibular
– Maxillary premolar 1 is
wolf tooth
– Canine teeth
• Rudimentary and
commonly fail to erupt
in mares
Dyce et. al
Numbering Teeth
• Can not definitively
tell which side without
obliques
• Make sure to call them
maxillary or
mandibular
• Always look for wolf
teeth
Teeth cont.
Mandibular
4th premolar
= Canine Tooth
Incisors
P2
P3
P2
P3
P4
P4
M1
M2
M1
M2
M3
M3
Tooth root fractures
(maxillary molars)
Ruminants
Horns:
- Grow from frontal bones
Dental Formula
Temporary Teeth:
Permanent Teeth:
• 0-0-3 Maxillary
• 3-1-3 Mandibular
• 0-0-3-3 Maxillary
• 3-1-3-3 Mandibular
Lumpy Jaw
(Actinomyces bovis)
Test yourself
• What
structures
can you
correctly
identify?