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Annulus fibrosus

(See also: Annular Tear)


  • anulus fibrosus makes up peripheral portion of disk structure;
  • composed of fibrocartilage and type I collagen;
  • fibers of anulus run obliquely between vertebrae and are arranged primarily in concentric layers;
    • direction of the fibers in successive layers alternates, w/ one layer crossing another at angles of 30-60 deg;
  • at periphery some annular fibers extend past cartilage edge plate to enter the bone of body as Sharpey's fibers;
    • deep fibers either insert into the cartilage at each end of disc or bend w/ nucleus pulposus;


  • neural fibers are found in the outer rings of anulus;
  • nerve fibers are branches of the sinu vertebral nerve dorsally;
  • ventral branches arise from the sympathetic chain that courses anterolaterally over the vertebral bodies;

Annular Tear »

Disc Herniation »

  • anulus is wider anteriorly than posteriorly (i.e., Nucleus pulposus is situated eccentrically)