Lumbar Spine Anatomy & Definitions Flashcards
trabeculae
- cancellous or spongy bone
- stabilizes longitudinal loads
- advantage: solid structures are not ideal for dynamic load bearing/solid.
vertebral body
the thick oval segment of bone forming the front of the vertebra also called the centrum. The cavity of the vertebral body consists of cancellous bone tissue and is encircled by a protective layer of compact bone
pedicles
two thick pillars of bone that project post/lat. from the upper part of the back of the vertebral body; transmits forces
posterior elements of the vertebral body
- laminae
- pars interarticular processes
- spinous processes
- transverse processes
- mammillary process
- site of muscular attachment
laminae
bony protective covering over neural contents of vertebral canal; absorbs forces from spinous & articular processes.
-stability of the lumbar spine can be compromised when a lamina is destroyed or weakened by disease, injury, or surgery
pars interarticularis
- connects vertically oriented lamina & horizontally extending pedicle
- subject to considerable bending forces as the forces transmitted by the lamina undergo a change of direction into the pedicle
- cortical bone in this area thicker than anywhere else in the lamina
mammillary process
- multifidi muscle attaches
- helps stabilize the vertebral joints
What percent of the nucleus pulposus is water?
85%
What percent of the nucleus pulposus is collagen?
15-20% chondroblasts
What type of collagen is produced in the nucleus pulposus?
type II - resisting compression
What percent of the nucleus pulposus is proteoglycans?
65% of dry weight
What are the effects on the nucleus pulposus with aging?
- water goes from 85% to 70%
- increased type I collagen fibers (type II collagen is produced normally)
- decrease in proteoglycans
- decrease aggregates & decreased capacity for osmosis
What percent of the anulus fibrosus is water?
60-70%
What percent of the annulus fibrosus is collagen?
50-60% of the dry weight (arranged in a highly ordered pattern, type I most dominant resisting tensile forces)
What percent of the annulus fibrosus is proteoglycans?
20% of dry weight
What are the effects on the annulus fibrosus with aging?
- reduction of water from 60/70% to 50%
- increase in type III collagen fibers (type I is normally most dominant)
- decrease in proteoglycans
lamellae
-sheets that are arranged in concentric rings that surround the nucleus pulposus. thicker towards the center of the disc, thick in the ant/lat portions of the annulus, but posteriorly they are finer & more tightly packed
How are the collagen fibers oriented diagonally?
-alternate successive lamellae
How are the collagen fibers oriented vertically?
-always the same, 60 degrees
What is the advantage of the collagen fibers in the intervertebral disc being oriented vertically and diagonally?
-each fiber can offer a component of resistance both vertically & horizontally which allows it to resist movements in all directions
What is the sensory innervation for the intervertebral disc?
-sinuvertebral nerve off of the anterior primary rami
What is the function of the IVD?
-the disc allows movement between the vertebral bodies by transmitting loads from one vertebral body to the next
If a weight is applied to a disc, how do it’s volume and shape react?
-the disc can become deformed but it’s volume cannot be compressed
blood supply of the IVD
nonexistent
In nutrition of the IVD, what does the activity of the cartilage cells in the NP and the fibroblasts in the AF provide?
-constant synthesis and replacement of proteoglycans & collagen
In a healthy disc, how long does it take to lose 12% of water?
-4 hours
In a degenerated disc, what percentage of water is lost at 4 hours?
-25%
What are 3 factors that affect the water loss in the intervertebral disc?
- smoking
- vibration
- lack of movement
disc pumping
-dehydration/rehydration; dehydration will allow subsequent rehydration and rehydration will allow subsequent dehydration
optimal stimulus for the annulus fibrosus
rotation (modified tension in the line of stress
optimal stimulus for the nucleus pulpusus
intermittent compression/decompression
vertebral end plates
-layer of cartilage that covers the area between the body and the disc - covers the NP in its entirety but peripherally fails to cover the entire extent of the annulus fibrosus
Sharpey’s fibers
-where the end-plate is deficient, the superficial collagen fibers of the AF insert directly into the bone of the vertebral body (these are the sharpey’s fibers)
Schomorl’s nodes
-discal material prolapsed through cartilaginous end-plate
inter-body joint
-joint formed between two vertebral bodies and are designed as the principal weight-bearing components of the lumbar spine
principle function of the zygapophyseal joint
provide a locking mechanism that resists forward sliding (anterior shear forces), excessive rotation & flexion of vertebral bodies
What percent of the weight-bearing load do the facet joints take when standing upright?
approx. 16%
optimal stimulus for regeneration of the zygapophyseal joints
compression/decompression with glide
meniscoids
-meniscus that attaches to capsule and functions as a space filler. may protect exposed joint surfaces during flexion & extension & increase the articular surface area without reducing flexibility
PPIVM
- passive physiological intervertebral movements
- flexion & extension
Where do lumbar spinal nerves exit the vertebra?
-below their vertebral level
lumbosacral plexus
-sacral plexus nerve passes through greater sciatic foramen, below the piriformis muscle
Which nerve is the largest branch of the lumbar plexus?
femoral nerve
What is the nerve supply to the outer half of the intervertebral disc?
sinuvertebral nerve and the grey rami communicants
nerve supply to zygapophyseal joints
medial branch of the dorsal primary ramus
biomechanics of flexion in lumbar spine
-combination of anterior sagittal rotation & small amplitude of anterior translation (straightening or minimal reversal of the lumbar spine lordosis)
biomechanics of extension in lumbar spine
-combination of posterior sagittal rotation & minimal posterior translation
Why are the facets of L1-L4 vertically oriented to the sagittal plane?
-to facilitate flexion/extension and limit rotation and side bending
How and why are the facets of L5-S1 orientated?
-oriented obliquely in the frontal plane resisting flexion/extension
coupled movement
-movement that is natural for the joint system, the capsule will limit the movement
combined movement
-movement that is not natural for the joint system. compression or approximation of the joint surfaces will limit mobility
avulsion fracture
-inadequate anchorage of the fibers of the annulus fibrosus. seen in younger population, traumatic history, spontaneous resolution of symptoms
external disc disruption (EDD)
-nucleus material begins to migrate through the annular fibers
transverse radial fissures
-annulus splits from inside to out; seen in acute disc related disorders
rim lesion
-transverse annular tear; partial detachment of annulus to the rim of vertebral body; starts mid & goes post/sup portion of disc
concentric delamination
-circumferential tear; nucleus loses water, annulus buckles & layers separate all around
internal disc disruption (IDD)
-young, veritable non-capsular pattern, negative tension signs
IVD degeneration/spongylosis
-disc begins to age and degenerate (< 20 years old)
IVD injury
-primary mechanism of injury to a lumbar disc is sustained or repetitive lifting (simply forward bending of the trunk), especially during rotation, with a neutral, non-flexed lumbar spine
herniated nucleus pulposus (HNP)
-disorder in which there is displacement of the nuclear material and other disc components beyond the normal confines of the annulus
protrusion (ProT)
-displacement of nuclear material beyond inner annulus causing bulge in outer annulus without escape of nuclear material (outer annulus is intact)
prolapse (ProL)
-displacement of the nuclear material beyond inner annulus with escape of nuclear material
central prolapse
-intact but irritated PLL, lumbar kyphosis, bilateral LE pain, saddle anesthesia, possible positive Cauda Equina syndrome
PLL prolapse
-far outside PLL
extrusion (ExT)
-annular fibers disrupted such that nuclear material extrudes into the spinal canal. PLL ruptured, considered to be a sick disc and unstable
DRG with disc involvement signs and symptoms
-if pt complains of noticing sensory symptoms first, think secondary disc & primary dorsal root
ventral root with disc involvement signs and symptoms
-if pt complains of nothing motor symptoms, first think primary disc and secondary ventral root
spinal nerve with disc involvement signs and symptoms
-mixed ventral and dorsal nerve root signs and symptoms
intermittent claudication due to ischemic impairment of the lumbosacral plexus (vascular claudication)
- 40-60+ years
- pain usually bilateral, occurs in calf (foot, thigh, hip, or buttocks) & no burning or dysesthesia
- pain consistent in all spinal positions
- pain brought on by physical exertion, relieved promptly by rest (1-5 min), and increased by walking uphill
- OE findings: decreased or absent pulses in LE, color & skin changes in feet; cold, numb, dry, or scaly skin; and poor nail & hair growth
spinal stenosis/neurogenic claudication
- disorder of the elderly
- 65% of pts with spinal stenosis also present with neurogenic claudication
- pain usually bilateral & occurs in back, buttocks, thighs, calves, & feet
- burning & numbness present in LE
- pain decreased in spinal flexion & increased in spinal extension & with walking
- pain decreased by recumbency (walking uphill)
- pain relieved with prolonged rest (may persist hours after resting in spinal stenosis)
- OE findings: normal pulses and good skin nutrition
LS OE Sequence in standing
- observation
- functional test
- ROM flexion
- ROM extension
- ROM R side bend
- ROM L side bend
- quadrant
- neurological exam: S1 myotome (calf raises)
LS OE Sequence in supine
- neurodynamic testing: PNF
- neurodynamic testing: SLR
- L2 myotome (hip flexors)
- L3 myotome (quads)
- L4 myotome (ant tib)
- L5 myotome (great toe ext & toe extensors)
- S1 myotome (peroneals)
- S2 myotome (toe flexors)
- L2 dermatome
- L3 dermatome
- L4 dermatome
- L5 dermatome
- S1 dermatome
- S2 dermatome
- L4 reflex (patellar)
- L5 reflex (hamstrings)
- S1 reflex (achilles)
- strength of lower abdominals
- muscle length tests: hamstrings
LS OE Sequence sidelying
- PPIVMS
- anterior stability test
- muscle length test: over
- muscle length test: piriformis test
- MMT: glute med
LS OE Sequence prone
- L5/S1 myotome (hamstrings)
- S1/S2 myotome (glute max)
- neurodynamic testing: prone knee bend
- repeated extension in lying
- strength of multifidus
- palpation [temp/sweating, scratch test, skin rolling]
- palpation [S2/PSIS, SP of S2-L5, central PA’s pass 1, central PA’s pass 2, confirm findings]
- palpation [unilateral PA’s pass 1, unilateral PA’s pass 2, confirm findings]
- prone stability test
LS OE Sequence sitting
- slump
- muscle length tests: illiopsoas, TFL, rectus femoris
Signs/symptoms of cauda equina syndrome
- Bowel & bladder dysfunction
- Saddle anesthesia
- Gait/coordination disturbances (global or progressive weakness in LE, sensory deficits in feet L4 L5 & S1/may complain of electrical shock in LEs)
- Sexual dysfunction
- Neurological signs: positive babinski, increased DTRs
L4 reflex
-patellar
L5 reflex
-hamstrings
S1 reflex
-achilles
What tests should be done in order to clear the SIJ & hip during the LS OE sequence while in supine?
SIJ clearance: gapping, gaenelson’s, thigh thrust, distraction, form/force closure
Hip clearance: F, IR/ER/ Scour, FADIR
What test should be done in sidelying to clear the SIJ during the LS OE sequence?
-compression provocation test
What test should be done in prone to clear SIJ during LS OE sequence?
-sacral thrust provocation test
What is the anterior stability test testing for?
-hypermobility or instability and is used primarily to stress the integrity of the supraspinous ligament
What would be your hypothesis if a contralateral SLR reproduced a patient’s symptoms?
- prolapsed disc
- bilateral SLR, sidelying SLR, prone SLR, hip flexion or knee extension would all cause irritability
What does the prone knee bend primarily test for?
-nervous system primarily through femoral nerve to L2, L3, & L4 nerve roots and meninges
L1 neurogenic referred pain areas on the body?
- above iliac crest
- groin
L2 neurogenic referred pain areas on the body?
- across iliac crest
- anterior proximal thigh
L3 neurogenic referred pain areas on the body?
- below iliac crest/above greater trochanter
- anterior-medial aspect of distal thigh/anterior-medial lower leg
L4 neurogenic referred pain areas on the body?
- across the greater trochanter
- anterior-lateral thigh/anterior-medial distal leg/hallux
L5 neurogenic referred pain areas on the body?
- across the ischial tuberosity
- lateral thigh/lateral distal leg/dorsum of foot/middle 3 toes
S1 neurogenic referred pain areas on the body?
- medial to the ischial tuberosity
- posterior thigh/posterior lower leg/lateral foot and toe 5
S2-3 neurogenic referred pain areas on the body?
- saddle area
- medial thigh/medial aspect of heel (S2 only)
referred, non-radicular pain locations for L1
-groin
referred, non-radicular pain locations for L3
-“in the knee” (or hip or knee)
referred, non-radicular pain locations for L4
- lower abdominal symptoms, testicular pain
- “in the ankle” or band around ankle & greater trochanter
referred, non-radicular pain locations for L5 segment
-upper lumbar pain
referred, non-radicular pain locations for L5/S1 referral
-coccyx symptoms
Discogenic Referral
- Vague Ache to buttock/LE
- Deep spot of pain to buttock
- Lower Lumbar disc: ant thigh pain/groin
Genitourinary Referral
- Lumbar Spine
- Hip
- Pelvis
- Sacral/perineal
Diverticulitis Referral
- Left lower quadrant
- Low back pain
- pelvic pain
- can refer to hip/thigh with abscess formation
