Spine Anatomy

DISC
  • Annulus fibrosis: Type I collagen
  • Nucleus propulsus: Type II collagen
  • Collagen: Stain PTAH, hydroxyproline + hydroxylysine + vitamin C
DEGENERATIVE DISC
  • MoA: Nucleus propulsus glycosaminioglycans replaced by collagen & elastin --> water composition decreases 90-65%
  • Endplate less vascular
JOINTS
  • Facet joints = apophyseal joint = zygapophysesal joint
  • Shrinking discs --> misalignment of facets --> degenerative change
  • Sx: pain worse w/ flexion
  • Epi: peak age 20-45 yo
BONES
  • Sharpey's fibers: annulus connected to bone, where osteophytes tend to form
SPONDYLOSIS
  • MoA: as discs degenerate & joints wear out --> hypertrophy of facets (esp SAF), bones rub vs. each other --> spurs / osteophytes (common C5-7 b/c of increased mobility)
NERVES
  • Sinuvertebral nerves: branch from posterior divisions of spinal nerves, just distal to DRG and re-enter the intervertebral foramina to innervate the ligaments, periosteum, outer annulus, and facet capsules
  • Spinal nerves: 31 paired (8 cervical, 12 thoracic, 5 lumbar, 1 coccygeal)
    C1 & Coccygeal roots with no dorsal roots; therefore, no dermatomes