Vertebrae Orientation

Posted bythespinebookadminPosted inAnatomy, Topics

Overview 

  • 33 vertebrae (24 mobile) 
  • 7 cervical 
  • 12 thoracic 
  • 5 lumbar 
  • 5 sacral (fused) 
  • 4 coccygeal (fused) 

Disc Anatomy 

  • Vertebral end plate 
    • 1mm fibrocartilage and hyaline cartilage  
    • Increasing ration of fibrocartilage: hyaline 
  • Nucleus Pulposus 
    • Mucoid 
    • 70-90% water 
    • Dry weight 
      • 65% proteoglycan 15% collagen (Type 2) 
  • Annulus fibrosus 
    • 12 lamellae concentric orientation 
    • Collagen fiber in alternating orientation in successive lamellae (vs multidirectional strain) 
    • 60% water 
    • Dry weight: 
      • 50% collagen (Type 1) 20% proteoglycan 
    • Water decreases with age 
    • Avascular – diffusion from end plate blood vessels 

Facet Orientation 

  • Cervical 
    • Sagittal 
      • 35 at C2, increasing to 55 at C7 
    • Coronal 
      • neutral 
  • Thoracic 
    • Sagittal 
      • 60 at T1 increasing to 70 at T12 
    • Coronal 
      • 20 degrees posterior 
  • Lumbar 
    • Saggital 
      • 135 at L1, decreasing to 120 at L5 
    • Coronal 
      • 45 anterior 

Cervical Spine 

  • Body 
  • Pedicle 
  • Facet (axially oriented to allow rotation) 
    • Saggital 
    • Coronal –  
  • Lamina 
  • Special  
    • Transverse Foramen C7-C2 
      • Vertebral artery only through C6-C2 
        • C1C2 there is more rotation 
          • It leaves C2 more laterally than levels below  
    • Bifid  
      • C7 non 
      • C6 variable 
      • C5-C1 
    • OC1 
     
    • C1C2 
      • Atlanto axially axis 
        • Dens process 
        • 50