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Intervertebral Discs

The intervertebral discs are the elastic ring-shaped structures connecting the bodies of the vertebrae. It constitutes 20–33% of the entire height of the vertebral column1, a number that decrease with age and inevitable progressive disc degeneration2.

  • 1 White, A. A. & Panjabi, M. M. Clinical Biomechanics of the Spine. Lippincott Williams & Wilkins, 1990.
  • 2 Urban, J. P. & Roberts, S. Degeneration of the intervertebral disc. Arthritis Res Ther 2003, 5(3):120–130.
    • Icon of crossfade image The spine with the intervertebral discs. Multiple views
    Human spine with the intervertebral discs The spine with no intervertebral discs
    The intervertebral discs are localized in between all the vertebrae except for the atlanto-axial and sacral localization. The bodies of the sacral vertebra ossify in the fetal period, before the eighth week of gestation1, so at birth, the sacrum is rather a single bone. In about 2.7%, the ossification of the sacrum also involves the 5th lumbar vertebra (the so-called sacralization of the lumbar spine). By contrast, about 6.2% of the first sacral vertebra do not fully fuse with the rest of the sacrum (the lumbarisation of the sacrum)2.
  • 1 Bagnall, K. et al. A radiographic study of the human fetal spine. 2. The sequence of development of ossification centres in the vertebral column. J Anat 1977, 124(Pt3):791–802.
  • 2 Nakajima, A. et al. The prevalence of morphological changes in the thoracolumbar spine on whole-spine computed tomographic images. Insights Imaging 2014, 5(1):77–83.
    • Icon of crossfade image The lumbar spine with the intervertebral discs
    Lumbar spine with the discs. Anterior and lateral view of the lumbar spine Multiple aspects of the lumbar spine with no intervertebral discs
    The intervertebral discs in the lumbar region have to support the body's weight and provide a substantial range of motion, so they are larger and higher compared to the thoracic and cervical discs. The peripheral part of the disc – the annulus fibrosus – consists of concentric, laminated bands of collagen fibers arranged in alternating directions. The annulus fibrosus uniformly surround the gel-like derivate of the embryonal notochord – the nucleus pulposus*.
  • * Lawson, L. & Harfe, B.D. Notochord to nucleus pulposus transition. Curr Osteoporos Rep 2015, 13(5):33-341.
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    Icon of crossfade image The lamellar structure of the lumbar intervertebral disc. The functional unit.
    The functional unit: lumbar vertebrae with the intervertebral disc
    The side view of the L2–L3 intervertebral disc.
    The laminated bands of the annulus fibrosus are oriented obliquely in alternating directions in about 30° with respect to the disc plane*.
  • * Inoue, H. Three-dimensional architecture of lumbar intervertebral disc. Spine (Phila Pa) 1981, 6(2):139–146.
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    Icon of crossfade image The thoracic spine with the intervertebral discs.
    The thoracic spine with the discs. The lateral aspect The thoracic spine with no interverebral discs
    The lateral view of the thoracic spine with the intervertebral discs.
    The thoracic intervertebral discs are similar to the lumbars and include both – annulus fibrosus & nucleus pulposus. However, the height of the thoracic discs is smaller compared to the lumbars*, which reflects the limited (compared to the cervical & lumbar) flexibility of the thoracic spine. Please note that the intraarticular ligamentum capitis costae connects the crest on the head of the rib directly with the thoracic intervertebral disc.
  • * Pooni, J. et al. Comparison of the structure of human intervertebral discs in the cervical, thoracic and lumbar regions of the spine. Surg Radiol Anat. 1986, 8(3):175–82.
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    Icon of crossfade image The cervical intervertebral discs. The cervical spine with discs.
    The superficial appearance of the cervical intervertebral disc Deep structures of the cervical intervertebral discs
    The cervical spine with the intervertebral discs. Click the image to switch between the superficial & deep components of the cervical disc.

    The cervical intervertebral discs differ significantly from the lumbar discs1 – the cervical anulus fibrosus does not consist of concentric lamellae of collagen fibers that uniformly surround the nucleus pulposus. Rather, the cervical anulus is crescentic, being thick anteriorly but tapering in thickness laterally as it approaches the uncovertebral region2.

    The superficial fibers of the anulus fibrosus run more vertically compared to the lumbar discs. Deeper the anulus fibrosus transforms into the homogeneous mass – the fibrocartilage core2 –, that, possibly, during disc aging and maturation, gradually substitutes the nucleus pulposus3–5.

  • 1 Bland, J. & Boushey, D. Anatomy and physiology of the cervical spine. Semin Arthritis Rheum 1990, 20(1):1-20.
  • 2 Mercer, S. & Bogduk, N. The ligaments and annulus fibrosus of human adult cervical intervertebral discs. Spine 1999, 24(7):619–626.
  • 3 Taylor, J. Point of view: The ligaments and annulus fibrosus of human adult cervical intervertebral discs. Spine 1999, 24(7):627–628.
  • 4 Driscoll, S. et al. In-vivo T2 relaxation times of asymptomatic cervi al intervertebral discs. Skeletal Radiol 2016, 45(3):393-400.
  • 5 Chen, C. et al. Quantitative T2 magnetic resonance imaging compared to morphological grading of the early cervical intervertebral disc degeneration: an evaluation approach in asymptomatic young adults. Plos One 2014, 9(2):e87856.
    • First published: 20/May/2021
    Last update: 22/May/2021