Block 1 - Anatomy - Intro to Spinal Imaging Flashcards
What is a PA CXR?
A chest X-ray taken from behind (posterior - anterior)
What is an AP CXR?
A chest X-ray taken from the front (anterior - posterior)
Which is better for imaging the heart, an AP CXR or PA CXR?
PA CXR
How is a CAT scan image oriented?
Viewed as if looking up from the patient’s feet;
patient facing up (patient right side is on the viewer’s left side)
What joint between the atlas and axis allows for head shaking (head rotation: shaking head for ‘no’)
Atlanto-axial joint
What joint between the atlas and occiput allows for head nodding (head rotation: nodding head for ‘yes’)
Atlanto-occipital joint
When checking an X-ray for cervical alignment, what four alignments should be checked?
Anterior vertebral line;
posterior vertebral line;
spino-laminar line;
posterior spinous line
What can form on the edge of the vertebral cortical bone as a result of osteoarthritis?
Osteophytes (bone spurs)
What color is air on an X-ray? What color is metal and water?
Black; white or gray (depending on density)
Why are the vessels and GI tract so bright in this CAT scan? Why is the vertebra so bright?
Contrast dye;
dense calcium salts
What two structures make up the occipito-atlanto-axial complex?
The atlanto-occipital joint;
the atlanto-axial joint
The atlanto-axial and atlanto-occipital joints make up what complex?
The occipito-atlanto-axial complex
What vessels are most at-risk for disruption during dislocation of the atlanto-occipital joint?
The posterior inferior cerebellar arteries
(and the vertebral arteries themselves)
Disrupting what articulation can inhibit blood flow through the posterior inferior cerebellar arteries and vertebral arteries?
The atlanto-occipital joint
What type of fracture is especially likely to damage the atlanto-occipital joint?
A fracture of the C1 ring
What cranial nerves may be damaged by inhibited blood flow through the posterior inferior cerebellar arteries?
V, IX, X, XI
What type of joint are the atlanto-occipital and atlanto-axial joints?
Condyloid
What membranes support the atlanto-axial and atlanto-occipital joints?
Anterior and posterior atlanto-occipital membranes
What ligaments support the alanto-occipital and atlanto-axial joints?
The alar, cruciform, and transverse ligaments (as well as the tectorial membrane)
How should the patient be positioned to get a lateral X-ray of the thorax as shown here?
What might be some reasons that patients are only able to get AP X-rays?
They are too sick to get comfortably to the imaging suite
What is a double-contrast CAT?
Oral contrast is administered so the small intestine and colon can be checked in the CAT scan;
IV contrast is administered so that the vessels of the body can be seen
Which joints make up the atlanto-axial joints?
The inferior articular facets of C1 interacting with the superior articular facets of C2
Which joints make up the atlanto-occipital joint?
The superior articular facets of C1 interacting with the occipital condyles
What is proper spinal protocol in assessing a potential C-spine injury?
You must be able to see all 7 vertebrae and the thoracic 1
What should you never do with a potentially injured C-spine?
Flex, extend, or rotate it
(use a C-collar to stabilize and protect the neck)
What is a FAST scan?
A rapid, bedside ultrasound in the ED
(Focused Assessment with Sonography for Trauma)
For what is a FAST scan especially useful?
Checking for bleeding intro the mediastinum or other cavities
What is the most common type of odontoid fracture?
A type II
What type of insult can lead to a type II odontoid fracture?
Hyperextension or hyperflexion
What is another name for the hangman’s fracture?
Pars interarticularis fracture
What is lordosis in terms of tilt of the pelvis?
Anterior tilt of the pelvis
(with compensating swayback)
Which nerve exits at the L4-L5 intervertebral foramen?
Which nerve will be impinged if the L4-L5 intervertebral disk is herniated?
L4;
L5
(although L4 leaves at the the L4-L5 foramen, it leaves just above the disk while L5 passes down in front of it)
(remember, this is below the cona medullaris; there are plenty of free nerves around)
Which nerve exits at the L3-L4 intervertebral foramen?
Which nerve will be impinged if the L3-L4 intervertebral disk is herniated?
L3;
L4
What are the two principal internal ligaments of the dens?
The alar ligaments and the cruciform ligament
Why is the cruciform (or cruciate) ligament called the cruciform ligament?
It is cross-shaped, with a transverse portion and a superior and inferior longitudinal portion
The transverse ligament of the atlas is a portion of what larger ligament?
The cruciate ligament of the atlas
The superior and inferior longitudinal bonds of the atlas are portions of what larger ligament?
The cruciate ligament of the atlas
What X-ray angle is ideal for visualizing a pars interarticularis fracture?
Oblique
What is the arterial phase of an IV contrast dye?
What is the venous phase of an IV contrast dye?
The initial phase in which the dye is highlighting arterial structures;
the secondary phase when the dye moves from the arteries to highlight venous structures
