Figure 1
From: Arthritis and pain. Current approaches in the treatment of arthritic pain
Classification of pain. Nociceptive pain is triggered by tissue injury and activates unmodified nociceptive neurons (light arrow) inducing acute pain. In contrast, normally innocuous stimuli produce pain in neuropathic and neuroplastic conditions in consequence of sensitized nociceptive pathways (dark arrows). Note: Idiopathic pain omitted from figure. (Adapted from [3].)