Herniated Nucleus Pulpusos

Question 1

Intervertebral Disk

Answer 1

• Cartilaginous joint between adjacent vertebral bodies > mobility
• Shock absorber
• Anulus Fibrosus

Question 2

Anulus Fibrosis

Answer 2

• Anulus Fibrosus
  
  • High water content > turgor
  • Distributes pressure throughout disc when weight-bearing
    
    • Weight bearing = compression > water squeezed from nucleus > nucleus thins
    • Non-weight bearing = elongation > water returns > nucleus thicker
    • With age > lose proteoglycans > bound water reduced > thinner disks > shorter as we get older
  • Outer portion – fibrocartilage rings, fibrous connective tissue
  • Inner portion – nucleus pulposus (few cells, many proteoglycans)
  • Not central > towards posterior (anulus fibrosus thinner posteriorly)

Question 3

Anulus Fibrosis Rupture

Answer 3

• Age > degeneration / weight > pressure è annulus can rupture > nucleus pulposus herniates through the annulus posteriorly (than anteriorly):
  
  • Anulus thinner posteriorly
  • Flexion of the spine stretches the posterior portion of the annulus
  • And laterally bc:
    
    • Posterior midline of disk reinforced by the posterior longitudinal ligament
  • Posterior-lateral herniation > compression of spinal roots/cord
    
    • Dermatomes > sensory deficits
    • Mytomes > motor deficits

Question 4

Intervertebral Foramen Borders

Answer 4

• Formed from notches (of superior and inferior notches)
• Borders:
  
  • Anterior border
    
    • Body of above vertebrate
    • Intervertebral disk and body of below vertebrate
  • Posterior border
    
    • Inferior articular facet of above vertebrae
    • Superior articular facet of below vertebrae
    • Zygapophyseal joint
      
      • Osteoarthritic > impinge nerve
      • Thickening / thickening of ligamentum flavum
  • Superior and inferior
    
    • Pedicles

Question 5

Naming Spinal Nerves through Intervertebral Foramen

Answer 5

• One spinal nerve through each IV foramen > spinal nerve named according to foramen
  
  • Cervical nerves exit as soon as can > takes name of vertebrate below
    
    • C3 nerve between C2/C3
  • Thoracic/lumbar nerves exit as soon as they can > takes name of vertebrate above = associated with upper part of the foramen
    
    • L1 nerve between L1/L2
  • C8 nerve passes through foramen between C7 and T1
  • Intervertebral disc is associated with the lower part of the foramen

Question 6

Herniated Nucleus Pulposus

Answer 6

• Herniated nucleus pulposus - no symptoms; herniation crowds spinal nerve > symptoms
• Lumbar (most common)
  
  • Lumbar nerves exit from upper intervertebral foramen
  • Lumbar intervertebral disk at lower intervertebral foramem
  • Herniated nucleus pulposis impinges nerve of below vertebrae
  • L1/L2 herniation
    
    • L1 nerve above disk > L2 nerve impinged
• Cervical foramen small + disk forms anterior border of middle of foramen > impinged nerve is the nerve that passes through > nerve impinged = below vertebrae
  
  • C5/C6 herniation impinges the C6 nerve

Question 7

Stenosis

Answer 7

• May lead to nerve compression
• Foraminal stenosis
  
  • Narrowing intervertebral foramen (ie osteophytes) > spinal nerve compression
• Central stenosis
  
  • Narrowing vertebral canal > vertebral canal contents compressed (spinal cord, cauda equine, spinal nerves/roots)

Question 8

Normal Radiograph

Answer 8

Question 9

Radiograph: Herniated Nucleus Pulposus

Lumbar and Cervical

Answer 9

Cervical Herniated Nucleus Pulposus

Question 10

Dermatomes and Myotomes

Answer 10

• Sensory disturbance BEFORE weakness
• Dermatome
  
  • Region of skin that receives its sensory innervation from a single spinal nerve (arise from the same dorsal root ganglion) > pain, paresthesia, myesthesia, hypesthesia, anesthesia
• Mytome
  
  • Group of skeletal muscles that receive motor innervation from a single spinal nerve or ventral root (arise from the anterior horn cells within a single spinal cord segment) > paresis / paralysis

Question 11

Laminectomy

Answer 11

• Laminectomy to remove pressure from the nucleus pulposus (offloading spinal nerve)

Question 12

Radiograph: Compression Fracture