Editing Pain (section)

=== Nociceptive ===
{{Main|Nociception}}
[[File:Nociceptive pain.jpg|thumb|288x288px|Mechanism of nociceptive pain]]

Nociceptive pain is caused by stimulation of [[Sensory nervous system|sensory nerve fibers]] that respond to stimuli approaching or exceeding harmful intensity ([[nociceptor]]s), and may be classified according to the mode of noxious stimulation. The most common categories are "thermal" (e.g. heat or cold), "mechanical" (e.g. crushing, tearing, shearing, etc.) and "chemical" (e.g. [[iodine]] in a cut or chemicals released during [[inflammation]]). Some nociceptors respond to more than one of these modalities and are consequently designated polymodal.

Nociceptive pain may also be classed according to the site of origin and divided into "visceral", "deep somatic" and "superficial somatic" pain. [[Viscus|Visceral structures]] (e.g., the heart, liver and intestines) are highly sensitive to stretch, [[ischemia]] and [[inflammation]], but relatively insensitive to other stimuli that normally evoke pain in other structures, such as burning and cutting. [[Visceral pain]] is diffuse, difficult to locate and often [[referred pain|referred]] to a distant, usually superficial, structure. It may be accompanied by nausea and vomiting and may be described as sickening, deep, squeezing, and dull.<ref name = Urch>{{cite book | vauthors = Urch CE, Suzuki R |chapter=Pathophysiology of somatic, visceral, and neuropathic cancer pain |editor=Sykes N, Bennett MI & Yuan C-S |title=Clinical pain management: Cancer pain |edition=2d |isbn=978-0340940075 |publisher=Hodder Arnold |location=London |pages=3–12|date=26 September 2008 }}</ref> ''Deep somatic'' pain is initiated by stimulation of nociceptors in ligaments, tendons, bones, blood vessels, [[fascia]]e and muscles, and is dull, aching, poorly-localized pain. Examples include [[sprain]]s and broken bones. ''Superficial somatic'' pain is initiated by activation of nociceptors in the skin or other superficial tissue, and is sharp, well-defined and clearly located. Examples of injuries that produce superficial somatic pain include minor wounds and minor (first degree) burns.<ref name="isbn0-443-05683-8">{{cite book |vauthors=Coda BA, Bonica JJ |veditors=Panswick CC, Main CJ |title=Pain management: an interdisciplinary approach |publisher=Churchill Livingstone |location=Edinburgh |year=2000 |isbn=978-0443056833 |chapter=General considerations of acute pain |chapter-url-access=registration |chapter-url=https://archive.org/details/painmanagementin0000main }}</ref>