Lecture 37 - L-Spine Flashcards
5 characteristics of the L-spine
- 5 vertebrae
- No foramina transversaria
- No facet for rib articulation
- Pedicles pass almost directly posterior
- Large broad (superior to inferior) spinous process
3 characteristics of a typical lumbar vertebrae
- Kidney shaped
- Shell of cortical bone surrounding a cancellous core
- Cancellous core formed of horizontal and vertical trabecula
Vertebral body is made of [blank] and its function
Made of trabeculae which is important for compressive strength and resilience (load is sustained by combination of vertical pressure and transverse tension in trabecular
What are 2 ways the vertebral body provides support for loads through trabeculae
- Provides vertical load-bearing support to the vertebral endplates
- Horizontal trabeculae “ties” increase the stiffness of the vertical load bearing beams
(SUMMED UP: designed to resist vertical and horizontal forces)
What are the 2 facets that define a zygapophyseal joint
- Inferior articular facet
- Superior articular facet
2 characteristics of the inferior articular facet of zygapophyseal joint
- Biplanar
- Convex facing anterior and lateral
4 characteristics of the superior articular facet of the zygapophyseal joint
- Large concave facet facing posterior and medially
- Guide rails for sagittal and frontal plane movement
- Restrain axial rotation and excessive translation
- Protect discs from torsional and shearing strains
Zygapophyseal Joint Frontal Orientation function (2)
- Prevents anterior translation
- Favors axial rotation
Zygapophyseal Joint sagittal orientation function (2)
- Prevents axial rotation
- Favors anterior translation
Zygapophyseal Joint Biplanar orientation function
Limits both anterior translation and axial rotation protecting the discs from both rotation and shearing forces
T or F: The sagittal section of vertebral body demonstrates nearly horizontal orientation
F, vertical orientation
What happens to the joint as we move down the lumbar spine
The angle increases resulting in joints breaking down at L4/L5 due to harsh angle
Joint capsule 4 function (lumbar spine)
- Increases stability and allows ROM
- Space filler
- Increases surface area of contact when articular facets are impacted and transmit some load
- Protect articular surfaces as they are exposed to extreme flexion and extension
What is the intervertebral disc composed of (3)
- Nucleus pulposus
- Annulus fibrosis
- Vertebral End-Plate
What 2 structures surround the nucleus pulposis
- Annulus fibrosis
- Vertebral endplate
Summary slide of intervertebral disc for lumbar spine
3 characteristics of nucleus pulposus
- Semi-fluid gel
- 70-90% water
- Proteoglycans form 65% of dry weight
2 characteristics of annulus fibrosis (lamellar arrangement)
- Lamellae arranged in 10-20 concentric circumferential layers
- Thicker towards center of disc anteriorly and laterally
3 structural characteristics of the vertebral endplate
- 0.6-1 mm thick hyaline cartilage
- Covers all of nucleus but only center portion of annulus
- Firmly attached to the disc, but only loosely to the vertebral body
What happens to lesion at vertebral endplate
Denaturation of the nuclear material
What are the 3 functions of the lumbar spine
- To bear and transmit loads from torso to pelvis in erect posture or during dynamic movements (eg. forward bending)
- Provide significant part of the movement required for bending and reaching
- Provide stability in load-bearing
What are 5 characteristics of lumbar spine ROM
3 characteristics of lumbar spine loading
- Discs provide 85% of axial loading
- Facets provide 15% load
- Increased loading of facets in flexion and extension
Lumbar pressures that are commonly used in exercises and postures
- Standing = 100%
- Bilateral SLR (150%)
- Sit-ups (210%)
- Prone extension (130%)
What 4 structures of the l-spine does the dorsal ramus innervate
- Zygapophyseal joint
- Multifidus
- Long erectors
- Skin overlying midline of back
What are the 3 blood supplies of the spinal cord
- Anterior spinal artery
- 2 paired posterior spinal arteries
- Artery of Adamkiewicz (T9-T10 feeder)
What is the blood supply of the nerve root
- Distal nerve root supplied by radicular branch of lumbar arteries
- Proximal nerve supplied by proximal radicular branches derived from anterior and posterior chord supply
What are the 3 functions of the multifidus muscle
1) Unilaterally: Bends spine to same side and rotates opposite
2) Bilaterally: Extends spine
3) Primary stabilizer for back along with oblique and transverse abdominal muscles
What are the 2 ligaments of the lumbar spine
- Anterior longitudinal ligament
- Posterior longitudinal ligament
What is the projections of healing from lower back pain
- 70-80% of pop. improve in 3 month period
- 50-80% will have one recurrent episode
- 20-30% can become persistent and disabling
3 characteristics of the pars interarticularis
- Part of laminae of superior and inferior articular process at junction of vertical laminae and horizontal pedicle
- Subject to bending forces
- Some individuals it is not thick and is susceptible to fatigue or stress fractures (spondylolesthesis)
What are the 3 biomechanical components for flexion of the lumbar spine
1) Anterior sagittal rotation (8-13 degrees)
2) Anterior translation (103 mm)
3) Facet joints glide superiorly and anterior during flexion
What are the 4 biomechanical components for extension of the lumbar spine
- Posterior sagittal rotation
- Posterior translation 1.1-1.7mm
- Limited when inferior articular processes are forced against lamina of the vertebrae below
- Facet joints glide inferior and posterior
What are the biomechanical components for rotation at the lumbar spine
- Twist of spine accompanied with lateral flexion
- After 3 degrees of rotation, the axis shifts to the facet joints
- Contralateral facet compressed
- Ipsilateral facet gapped
- Disc is strained by torsion and lateral shear
- Rotation resisted by disc (35%) and posterior elements (65%)
