Anatomy of small animal Flashcards
Orthogonal views
Always take two images that are 90 degrees apart
Collimation
-proper collimation reduces the amount of scatter radiation produced
*better radiation safety and increase image quality
Centering the X-ray beam
X ray beam will exit the source as a fan so direct middle of fan perpendicular
*mild distortion may be present at the edge of the field of view due to the divergence of the beam
Center the X ray beam in the axial skeleton
-Need to take spine radiographs in 4-5 collimated imaged, not 1 large image
*this ensures that you don’t get divergence artifacts and “small looking spines”
Bone cortex
-dense outer layer
-includes periosteum and endosteum
Medulla
-grainy opacity because porous cancellous bone
*honeycomb cavities
Subchondral bone
Bone immediately adjacent to the articular cartilage
-changes often indicate problems with the cartilage
Diaphysis
-central portion of the long bones
Metaphysis
transition from physis to diaphysis
Physis
-growth plate in immature animal
-physeal scar in mature animal
Epiphysis
-between joint space and physis
Apophysis
-arise from a separate center of ossification and eventually fuses with the rest of bone
*tendon or ligament attachment
Sesamoid bones
A small bone embedded within a tendon or muscle
-acts like a pulley providing a smooth surface for tendon to glide
Where are there normal unexpected physes?
-elbow joint
-illeal wings
-pelvis
Vascular canals
Cutback zones
-occur in rapidly growing animals (often large breed dogs, horses)
-flaring of the metaphysis adjacent to physis
Cutback zone
Skull radiographs
-need deep sedation or GA
-Prefer DV view, and then lateral. But many other views possible
-need to elevate the nose
What indicates a good DV/VD skull radiograph?
Equal spaces between the mandibular rami and the zygomatic arches
What indicates a good lateral skull view?
Mandibles and tympanic bullae are superimposed
What view for temporomandibular joints?
Use nose up lateral oblique view
*eliminates superimposition of the two TMJ joints
What view would you use for nasal cavities?
Open mouth/intraoral VD view
-eliminates superimposition of the mandibles with nasal cavity
What radiograph do you use for viewing the frontal sinuses?
Rostrocaudal view
Canine skull anatomy
Brachycephalic breeds
Dolichocephalic breeds
Feline skull
Pharynx/larynx views
Spine radiographic positioning
-take several colimated images
-position devises needed to prop sternum and spine in the same plane in lateral views
VD spinal radiographs
-need dorsal spinous processes completely end on
-straight alignment of vertebral bodies
Lateral spinal radiographs
-need discrete margins of disc space
-well defined and equal sized intervertebral foramina - “little horse heads”
-superimposed ribs and transverse processes
Key points to spine radiographs
-no disc between C1-C2
*C1- large wings
*C2-spinous process + cranial process=dens
- C6 has large transverse processes
-T11 or T10 is anticlinal vertebra
Issue with dens
Axial subluxation
-common in small breed dogs
How can you better see dens in radiographs?
15 degree oblique lateral
Thoracic spine
Anticlinal
spinous process becomes vertical to body= anticlinal= most dogs T11, some T10
**lumbar spinous processes start after this= more upright
Transitional vertebrate
Vertebrate with features of both thoracic and lumbar or cervical or thoracic spine
eg. T13- one single rib= half lumbar and half thoracic
Hemivertebrate
-Common in bulldogs, boston terriers, pugs
-short malformed vertebrae; incomplete fusion
linked with rib crowding, spinal kyphosis, scoliosis
-not linked with neurological signs
What are the common locations of hemivertebraes?
-T7
-T8
-T12
-occasional lumbar
Lumbar spine
Diaphragm crura attachment sites
-L3 and L4 making the radiographs not as clear at their border
Lumbosacral junction
Transitional L7 with the sacral body
-eg. right side short and articulating with sacral; long left side still present
Caudal vertebrae
-Normal: even, gradual reduction in size
*brachycephalic breeds often have corkscrew tail
*cats= coccygeal vertebrae dysgenesis= no tail formation
Interpretation of spine
ex.
soft tissue thickening
*abnormal because focal
When you see this, must look at associated bone
*right sided aspect of vertebral body is “eaten away” or lost
What special views should be done to ensure proper visualization of humeral head?
- supination lateral view
- pronation lateral view
What view should you use to see the biceps tendon and sheath?
Cranioproximal-craniodistal oblique view to skyline the intertubular groove (bicipital groove)
What are normal shoulder findings on radiographs?
Humerus
Not really any pathology with these parts
What are the standard views for the elbow?
- Lateral
- Flexed lateral
- Craniocaudal
What is the purpose of the flexed lateral view for the elbow joint?
Allows you to see the anconeal process without superimposition with the medial humeral condyle
*look for fragmentation of anconeal process
Elbow anatomy
Antebrachium
Manus anatomy
What views should be used to radiograph pelvis?
- lateral
- VD with legs extended
*preferred over frog leg - VD frog leg
**need straight views to ID structures and symmetry
Pelvis anatomy
Lateral pelvic views
Stifle anatomy
What are normal stifle findings what may be mistaken for pathology?
Crus
How do you see lateral talar trochlear ridge?
Use flexed DP view
Tarsus
Stress views
Palpate issue, take image of stressed joint in all 4 different directions
*then see where the instability is
*if looking at medial aspect, put stress on lateral aspect
