the thing about "moment arms"
- the longer the arm, the more force is needed to hold the same wt
- so, if yr arm is outstretched and you're holding even a small wt, the paraspinal muscles have to create a lot of force to stabilize the spine, bc these muscles (erector spinae) have short moment armsthe forces are transmitted to vertebral discs
which abs contract to support the spine
- transverse abdominus
- with multifidus
DDD almost always happens at which disc space?
stress riser effect
location in an object where stress is concentrated, so the object is likely to fail there
name something that creates stress risers in the spine
- surgical fusion
- this results in acceleration of degenerative changes adjacent to the sites of fusion
3 characteristics of lumbar vertebrae
- large bodies
- large facet joints and SPs
- neural foramina exit in coronal plane
divides bony in to dorsal/ventral sides
in which plane do the neural foramina exit in the lumbar vertebrae
in a lateral view of lumbar vert, as you move more laterally, posteriorly you'll first see the SPs, then what?
- sup/inf articular facets
- pars interarticularis (btwn the above 2 on one vert)
- it's part of the lamina
- btwn sup and inf articular facets
- weakest part of the lamina
where's the ligamentum flavum?
- connects lamina of adjacent vertebrae
- in a lat view of the lumbar spine it's posterior of the spinal foramen
- concects the SPs along their bodies, not at their ends
- on a lat lumbar x-ray visible btwn SPs
epidural space is where on a lumbar vert x-ray?
it's dark, you can see it just post of the body of L5, it's a line ant to the cord
in an axial CT, where is the aorta?
ant and a bit off center from the vertebral body
on an axial CT how do you recognize the paraspinal muscles?
they're the lighter blobs posterolat to the SP
vertebral body endplate
on an axial CT
- endplate is the edge of the vertebral body
- neural foramen is the gap post to the body, ant to the SP
looking at facet joints on an axial CT, where is the "superior articular facet" and which facet belongs to the sup ver?
- the sup art facet is more lateral
- the sup vert's facets (it's inf art facets) are medial
how to find an intervertebral disc on an axial CT?
if you can't see the vert body, just a darkish outline of it, and if you're simultaneously seeing the facets, then that shadow of the body is the intervertebral disc
on a coronal view of the lumbar spine, what's directly sup and inf to a pedicle?
on a coronal CT of the lumbar spine, where is the pars interarticularis?
it looks like it's between the TP and the lamina
tell me about spotting the 12th rib in a coronal CT of the lumbar spine
- it'll be in a very posterior view, where you're only seeing the SPs
- the 12th ribs will appear as 2 SP-ish dots lat to T1
what to order for back pain w no recent trauma?
- nothing - it'll usually heal by itself
- BUT, when imaging is needed, go w MIR first
- x-rays "may be sufficient ofr the initial eval of the following red flags:" recent trauma, osteoporosis, age > 70
10 red flags for back problems
- recent significant trauma (or milder trauma if >50 y/o)
- unexpained wt loss
- unexplained fever
- immunosuppression (from a disease or drugs)
- history of cancer
- IV drug use
- prolonged use of corticosteroids or hx of osteoporosis
- age > 70
- focal neurologic deficit w progressive or disabling symptoms
- duration > 6 weeks
2 slides on pg 5 w details about what to order for specific complaints
I'm not typing these. Just review them before exams
lumbar views, and which 3 are the standards?
- spot lumbosacral
it's the first 3
how to find L5/S1 - 3 methods
- best method: count from the top
- or look for 12thr rib on lat or AP - it ends by the 1st lumbar vert
- look for the L/S junction (meeting of the arc of the sacrum and arc of the curving lumbar spine)
in a lat view what's a trick for identifying T12?
it has a white cloud cutting through the post portion of the body
you must go back to the slides and review the "be able to identify" lists on on pg 7
anatomy of the scotty dog
- eye = pedicle
- head/nose = TP
- neck = pars interarticularis
- ear = sup art facet
- front leg = inf art facet
- hindmost leg = SP
- other hind leg = inf art facet
spondylolisthesis vs spondylolysis
- movement of one vert body with respect to another
- fracture thru pars interarticularis
- lysis can lead to listhesis
- DDD can result in spondylolistheis w/o spondylolysis -- this is associated w spinal canal stenosis
breaking the spotty dog's neck is called what?
spondylolysis (spondylolisthesis is when there's movement of one vertebral body w respect to another)
gradings of spondylolisthesis
- <25% dislocation - grade 1
- 50% - grade 2
- 100 % (the post of the upper vert body is at ant spot of inf vert body) - grade 4
vacuum disc phenomenon
- happens w DDD
- when body moves w/o a disc this creates a vacuum that sucks gas from nearby structures, creating a very dark line btwn bodies
4 things that come with lumbar DDD
- disc space narrowing
- hypertrophic changes or osteophytes
- endplate sclerosis
- vacuum disc phenomenon
a visiple feature of anklylosing spondylitis
fusion of SPs
- mostly a soft tissue process
- on x-ray, look for destruction of endplates (they'll be concave)
- get MRI w contrast! but can still see some findings on x-ray
what to do if you suspect a tumor in the lumbar spine
get MRI or CT -usually don't need contrast w MRI if just assessing for cord compression
common causes for thoracic/lumbar spine injuries
- MVI > 35 mph
- falls > 15 ft
- MVP w pedestrian thrown > 10 ft
- assault w depressed consciousness
- known cervical spin injury
- rigid spine disease
bottom line for what to order fro T/L spine supsected blunt trauma
get CT first
where are most lumbar spine injuries?
thoracolumbar junction (stress riser)
for lumbar spine injuries get CT after abnormalx-ray except _ _ _
- stable compression fx
- isolated SP and TP fx
5 categories of lumbar spine injuries
- compression fractures - ant wedge or biconcave
- burst fx (axial load)
- chance fracture
- minor fractures (TP, SP, pars interarticularis)
lumbar ant compression fracture - 3 things to ask
- how much loss of ht?
- has there been a change in alignment?
- does the post wall of vert body look like it's encroaching on the spinal canal?
what's happening in an ant compression fx - what to do?
- mid and post columns intact
- nonoperative management
- stable if >40% loss of height, consider Burst or Chance fracture
- classic injury from lap seatbelt
- fulcum is ant to spine and results in distraction injury involving all 3 columns
it's a horizontal fx thru the vertebra
in scoliosis, meaning of dextro, levo, apex, cobb angle
- dextro: right
- levo: left
- apex: peak of curvature
- cobb angle: A line is drawn along the superior end plate of the superior end vertebra and a
- second line drawn along the inferior end plate of the inferior end vertebra. If
- the end plates are indistinct the line may be drawn through the pedicles. The
- angle between these two lines (or lines drawn perpendicular to them) is measured
- as the Cobb angle.
unique characteristics of thoracic spine
- more supported than lumbar spine
- smaller articular processes
- seperate articular facet for ribs (on lat/post body and lat TP)
- upper 4 are more like c-vert, lower 4 like L-verts, middle 4 are a combo
on an AP view of the thoracic spine where is the clavicle?
btwn T3 and T4, lower than the first 2 ribs
- diffuse idiopathic skeletal hyperostosis
- flowing ossification of the ant long lig
- the disc space is preserved
- usually asymptomatic save some loss of mobility which is protective against DDD
- one vert that comes up white (trabecular looks same as cancellous)
- could be: osteoblastic metastasis, lymphoma, Paget's disease, fluorosis, osteopetrosis
sacroiliitis - def and possible causes
- inflam of the SI joint
- ankylosing spondylitis
- inflam bowel disease
- Reiter's disease