4 – SA MSK Flashcards
Why is proper collimation important?
- Reduces amount of scatter radiation produced
o Better radiation safety practice
o Increased image quality
x-ray beams exit the sources as a fan
- *place the centre beam with the joint(s) of interest
- *mild distortion may be present at the edge of the field of view due to divergence of the beam
- Axial skeleton: 4-5 collimate images of the spine, NOT 1 large image of the entire spine
o Positioning devices needed to prop the sternum and spine in the SAME plane in lateral views
Cortex of bone *
- Dense outer layer of compact bone
- Periosteum: outer fibrous lining of cortical bone
o serves as protective layer, also attachment surface for tendons, muscles, and ligaments - endosteum: layer that lines the medullary cavity
Medulla of bone *
- porous cancellous/spongy bone deep to cortical bone
- honeycomb cavities form by a lattice work of trabeculae
Subchondral bone *
- bone immediately adjacent to the articular cartilage
- changes often indicate problems with the cartilage (not visible radiographically)
Diaphysis of bone *
- centre portion/shaft of long bones
- can often see vascular canals in them (usually in the middle)
Metaphysis of bone *
- transition from physis of diaphysis
Physis of bone *
- Growth plate in immature animals
- Physeal scar in mature animal
- Some physes can look like fractures
Epiphysis of bone *
- Between joint space and physis
Apophysis of bone *
- Arise from a separate center of ossification, eventually fuses with the rest of bone
- A site of tendon or ligament attachment
Sesamoid bones *
- Small bone embedded with a tendon or muscle
- Acts like a pulley, provides smooth surface for tendon to glide over
What are ‘cutback zones’ ? What animals are they seen in commonly?
- In rapidly growing animals
- *flaring of metaphysis adjacent to physis
- Means there is a lot of bone turnover/growth
- Common: large breed dogs and horses
Skull
- DV preferred over VD (easier to get it straight)
- *positioning device needed to elevate the nose
Skull DV/VD view
- Equal spaces b/w the mandibular rami and zygomatic arches
Skull lateral view
- Mandibles and tympanic bullae are superimposed
When do you do ‘nose up’ lateral oblique view?
- To view temporomandibular joints
o Eliminates superimposition of the 2 TMJ
When do you do open mouth/intraoral VD view ?
- For nasal cavities
- Eliminates superimposition of mandibles with nasal cavity
When do you do rostrocaudal view?
- For frontal sinuses
*What are some key anatomic features to see on a radiograph of a canine skull?
- Nasal planum and cavity
- Body of manible
- Ramus
- Tympanic bulla
- Frontal sinus
- Cranial vault
- Zygomatic arch
- Lateral aspect of ramus
- TM joint
*What are some key features you should look at in the pharynx/larynx?
- Nasopharynx
- Soft palate
- Oropharynx
- Pharynx
- Larynx
- *know general shape of hyoid apparatus
Straight spinal radiographs: VD view
- Dorsal spinous process completely end-on
- Straight alignment of vertebral bodies
Straight spinal radiographs: lateral view
- Discrete margins of disc spaces
- Well-defined and equal-size intervertebral foramina: “little horse heads”
- Superimposed ribs and transverse processes (“Nike”)
*What are some key anatomical landmarks of the spine on radiographs?
- C6 has large transverse processes
- T11 (sometimes T10) is the anticlinal vertebra (thoracic vertebra with a completely vertical spinous process)
*What are some key radiographic features of the spine?
- No disc between C1-C2
- Diaphragmatic attachments at L3 and L4 ventral aspects
o May cause indistinct ventral borders of the vertebral bodies