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. Author manuscript; available in PMC: 2015 Dec 1.
Published in final edited form as: Cytokine. 2014 Jul 24;70(2):185–193. doi: 10.1016/j.cyto.2014.06.019

Figure 1.

Figure 1

Nociceptors (medium-sized myelinated Aδ fibers and small unmyelinated C-fibers) detect noxious signals in the innervated tissues and carry them to the dorsal horn of the spinal cord. The cell bodies of these pseudounipolar nociceptors are located in the dorsal root ganglia (DRG) and extend axons to the periphery as well as centrally to the dorsal horn, where the first synapse occurs. In osteoarthritis, all joint tissues participate in driving progressive structural joint damage, including the articular cartilage, subchondral bone, and the synovial membrane. Ongoing chronic tissue damage and low-level inflammation generates cytokines and chemokines that may directly act on innervating nociceptors. The precise nature of this interaction in the arthritic joint has not been elucidated Osteoarthritis is a chronic and painful disease of synovial joints. Osteoarthritic joint tissues produce and respond to cytokines and chemokines. Cytokines promote joint destruction and directly activate innervating nociceptors.