Skip to main content
. Author manuscript; available in PMC: 2018 Jun 1.
Published in final edited form as: Biomaterials. 2017 Mar 15;129:54–67. doi: 10.1016/j.biomaterials.2017.03.013

Figure 1. Schematic of the intervertebral disc and anatomic sub-structures.

Figure 1

Abbreviations: AF, anulus fibrosus; IVD, intervertebral disc; NP, nucleus pulposus. (A) Forces of load bearing and motion contribute to axial loading of the IVD that is balanced by a hydrostatic pressure generated in the gelatinous NP. Pressure in the NP gives rises to a tensile stress in the surrounding AF or a “hoop stress” as depicted. (B) Multiple factors contribute to the onset of degeneration and matrix changes in the IVD, including aging, wear and tear of daily loading, inheritance patterns, and environmental factors such as pH, oxygen, and nutrient supply. (C) Anatomic changes in the substructures of the IVD can give rise to pain or disability due to proximity of the IVD with major sensory and motor nerves. Age- or pathology-related changes can contribute to an increased innervation of the IVD by sensory neurons branching from the dorsal root ganglion that are a purported cause of discogenic pain. (D) Disc degeneration is classified based on anatomic changes that may be distinguished by imaging appearance or gross morphology, as shown here. (i) Healthy young adult disc with a defined NP. (ii) Middle age adult disc that is slightly aged but not yet degenerated. (iii) Moderately degenerated young adult disc. (iv) Severely degenerated young adult disc. [Panel D modified from: Adams M. Anatomy and Physiology of the Lumbar Intervertebral Disc and Endplates. In: The Lumbar Intervertebral Disc. New York: Thieme Medical Publishers; 2010:14.]