Lumbar Spine Flashcards
What is the medial border of the nerve root canal?
Rural Sac
What is the posterior border of the nerve root canal?
Ligamentum flavum, superior articular process, and lamina
What is the anterior border of the nerve root canal?
Vertebral body and IVD
What happens to the nucleus pulposus with aging?
Water amount decreases, increased type 1 collagen fibers, decrease of proteoglycans, decreased capacity for osmosis.
What happens to the Anulus Fibrosis with aging?
Decrease in water, increase in type III collagen, decrease in proteoglycans.
How are lamellae arranged?
Arranged in concentric rings that surround the NP. The Labelle are thicker towards the center of the disc, thick in the ant/late portions of the annuls, but posteriorly they are finer and more tightly packed.
What happens with the lamellae with deterioration/dehydration?
The disc cannot maintain the 65 degree angle with respect to the vertical.
What is the advantage of the arrangement of the fibers of the lamellae?
Each fiber can offer a component of resistance both vertically and horizontally which allows it to resist movements in all directions.
What is the sensory innervation of the intervertebral disc?
The recurrent sinuvertebral nerve and it supplies the disc at its level and the level above.
What is the function of the IVD?
It allows movement between the vertebral bodies by transmitting loads from one vertebral body to the next. Also could have a proprioception function.
What part of the disc is most resistant to tension?
The ant/post portion
When do tensile forces occur with the IVD?
Rotation and compression
What resists the compressive forces in the IVD?
When the weight is applied to the nucleus, the nucleus may be deformed but the volume cannot be compressed. The NP reduces height and tries to expand radially towards the AF. The tensile properties of the AF resist the stretch.
What happens with a “shear” force of IVD?
One vertebra “sliding forward” on another - only the angular fibers oriented in the direction of the line of force will resist the motion (1/2 are stretched and 1/2 are relaxed)
How does the IVD receive nutrition?
Since there is no blood supply directly to the IVD, the disc relies on diffusion of water and nutrients from vessels surrounding the outer annuls and capillaries just beneath the vertebral endplates.
What is the optimal stimulus for regeneration?
Annuls: rotation. Nucleus: intermittent compression/decompression. Facets: compression/decompression with glide
What is the vertebral end plate?
The layer of cartilage that covers the area between the body and the disc. Covers the NP entirely, but peripherally does not cover the entire AF.
What are Shaper’s fibers?
Where the end plate is deficient, the superficial collagen fibers of the AF insert directly into the bone of the vertebral body
Where do L1 and L2 nerves exit?
Exit the intervertebral foremen above the disc
Where does L3 nerve exit?
Travels behind the inferior aspect of the vertebral body and the L3 disc
Where does L4 nerve exit?
Crosses the whole vertebral body to leave the spinal canal at the upper aspect of the L4 disc
Where does the L5 nerve exit?
Emerges at the inferior aspect of the fourth lumbar disc and crosses the fifth vertebral body to exit at the upper aspect of the L5 disc
Where does the S1 nerve exit?
Crosses the L5 disc
What is the never supply to the zygophyseal joints?
Medial branch of the dorsal primary ramus
What are the biomechanics of flexion?
A combination of anterior sagittal rotation and small anterior translation (minimal reversal of lordosis)
What are the biomechanics of extension?
A combination of posterior sagittal rotation and small posterior translation
What limits anterior rotation?
PLL (Posterior longitudinal ligament), LF (ligamentum flavum), ISL (interspinous ligament), SSL (supraspinous ligament), facet joint
What limits extension?
spinous process, Anterior longitudinal ligament, capsule
How are the facets of L1-L4 oriented and how does it effect the biomechanics
Vertically oriented to the sagittal plane facilitating flexion/extension and limiting rotation and lateral flexion
How are the facets of L5-S1 oriented and how does it effect the biomechanics
Oriented obliquely in frontal plane this resists flexion/extension
Describe coupled movements of the neutral spine
SB and rotation occur to the opposite side
Describe coupled movements of the extended spine
SB and rotation occur to the opposite side
Describe coupled movements of the flexed spine
SB and rotation occur to the same side