Lumbar Spine Flashcards
What structure does the spinal cord pass through?
vertebral foramen
Where do ligaments attach to on the spine?
spinous processes
How are spinal nerves named?
after the superior vertebrae
Where does spinal cord terminated? What does it become?
L1/L2; forms a point called conus medullairs, below this point is the caudal equina
Lumbar puncture
lumbar puncture is a needle that allows to get a sample of CSF from subarachnoid space
Epidural
an injection of medication (steroids, anesthetics, anti-inflammatories) into epidural space
Where are lumbar punctures/epidurals done? What level?
below conus medullar is (around L3/4) to avoid the spinal cord
Function of Intervertebral Discs
- allow movement between the vertebral bodies (squishy pad allowing for movement)
- transmit load between vertebral bodies (shock absorbers)
Components of IVD
- vertebral end-plate
- nucleus pulposus
- annulus fibrosis
Vertebral end-plate
- a layer of cartilage covering superior and inferior surfaces of disc
- firmly attached by sharpy’s fibres
- diffusion of nutrients from vertebral body to disc (it is a form of connection between disc and vertebral body)
Nucleus Pulposus
- semi-fluid gel
- 70-90% water
- proteoglycans make up 65% of dry weight- resist compressive forces
- deformable under pressure
- transmits applied pressure in all directions
- tolerant of compression, transmits pressure in all different directions
Annulus fibrosis
- made of collagen arranged in a highly ordered fashion (50-60% of dry weight)- resists tension
- collagen are arranged in 15-25 concentric, circumferential lamellae
- oriented 65% to the vertical
- retains nucleus pulposus
- absorbs compression and can tolerate tensile forces
Distraction
- superior-anterior glide of inferior articular process
- anthrokinematics; superior joint moving on inferior joint
- inferior articular process is on superior vertebrae, superior articular process is on inferior vertebrae.
- results in widening of IVF
- pulling bone off bone
- distraction can be used to treat
Compression
- Inferior-posterior glide of superior vertebrae
- inferior articular process of superior vertebra
- results in narrowing of IVF
- pinches nerve
- compression is used to diagnose
Disc Distraction
- separation of vertebral bodies increases the height of the IVD and all the collagen in annulus fibrosis are lengthened and tense, regardless of orientation
- tension through all collagen fibres
- distraction injuries are rare
Disc Compression
- raises the pressure in the nucleus pulposus which becomes exerted radially onto the annulus fibrosis increasing the tension in the annulus
- the tension in annulus is exerted on nucleus preventing it from expanding radially. nuclear pressure is then exerted on vertebral end-plates.
- vertebral end-plates transmit the load from one vertebrae to the next
Flexion(Anthrokinematics)
- superior-anterior glide of the inferior articular process of the superior vertebrae alone the superior articular process of the inferior vertebrae
Extension (Anthrokinematics)
- inferior-posterior glide of the inferior articular process of the superior vertebrae along the superior articular process of inferior vertebrae
- If you have radiculopathy; extension should decrease symptoms
Disc Flexion
- causes compression of annulus fibrosis in the direction of the movement and along annulus on the opposite side
- this pinches disc in the front which causes it to stretch out back
- forward bending: anterior end of vertebral body lowers will the posterior end rises
- nucleus pulposus will be compressed anteriorly and will migrate posteriorly
- when nucleus pulposus gets driven to the back it causes a disc herniation or bulge
Torsion
- collagen fibres of annulus oriented in the same direction as twist will be stretched and resist torsional force, remainder are relaxed.
- only half of the annulus can share stress of twisting
- this may be why torsion is one of the primary MOIs
Shear
- forward sliding, fibres angled forward on lateral aspect of disc will predominately resist movement as they lie parallel to movement
- anterior and posterior fibres make some contribution but not nearly as much as lateral fibres
- fibres angled posteriorly will be relaxed
Lumbar Lordosis Angle
L1-L5 (A angle)
Sacral tilt
- angle from vertical when we align with spinous processes of sacrum
Sacral Horizontal Angle
- angle derived off of horizontal where we’re looking at superior aspect of sacrum compared to horizontal and getting an angle
Lumbosacral angle
- (wedge angle) angle between inferior aspect of lumbar vertebral body L5 and the superior aspect of sacrum. Acute angle can see L5 wanting to migrate forward. Increase in this wedge angle, more likely it will want to shear
- between bottom of last vertebrae and top of sacrum
Lumbar Disc Herniation
- Pattern One
- displacement of disc material (nucleus pulposus or annulus fibrosis) beyond the intervertebral space
- herniation process begins from failure of innermost annular rings (lamellae) and progresses outwards to periphery or radially
- most often due to recurrent torsional strains (repetitive rotation)
- nucleus loses hydrostatic pressure and annulus bulges outward during disc compression
- when a tear occurs within fibres, material of nucleus pulposus can track out of the tear and into vertebral or iVF to impinge nerve structures
Bulge
extension of disc beyond margins of adjacent vertebral end-plate.
- instead of kidney bean shape, we have a bulge going beyond vertebral end-plate
Protrusion
- nucleus pulposus protrudes outward while annulus fibrosis remains in tact. start to get interruption of inner fibres which over time can lead into all fibres being compromised
Extrusion
- nuclear material emerges through annular fibres but the posterior longitudinal ligament remains intact
- wall of annulus fibrosis has ruptured and disc material is able to exit. PLL holds disc material inside
Sequestration
- nuclear material emerges through the annular fibres and the PLL is disrupted.
- a portion of nuclear material has protruded into epidural space, and material loses all connection with disc.
- body will sense disc material as foreign and cause inflammatory response
Dis Herniation (central-vertebral foramen)
- often associated with back pain only
- may present with cauda equina syndrome which is a medical emergency
- LMN lesion
- above conus medullar is = spinal cord compression - UMN lesion
Dis Herniation (posterolateral- IVF)
- most common (90-95%)
- PLL is weakest here
- can lead to lumbar radiculopathy
- LMN lesion
Region Specific (low back) Red Flag Screening
Cauda Equina (SPINE)
Cauda Equina S:
saddle anesthesia- loss of feeling around the buttocks, anus, and genitals
Cauda Equina- P
pain- severe nerve pain in back and/or down one or both legs
Cauda Equina- I
incontinence: bladder and/or bowel
Cauda Equina: N
numbness: lack of sensation and/or weakness in the leg (gait disturbance)
Cauda Equina: E
emergency: immediate referral to a neurosurgeon
Disc herniation most common at L4/L5 and L5/S1- shear
- dramatic shear or decrease in lumbosacral wedge cause excessive anterior shear of L4 on L5 and L5 on S1. this puts a lot of strain on collagen fibres and overtime it can disrupt annulus fibres allowing disc to migrate outside centre of disc