Somatic or visceral pain
Nociceptive pain is caused by a painful stimulus on special nerve endings, called nociceptors. Nociceptive pain in its acute form usually serves as an important biological (or evolutionary) function as it warns the organism of impending danger and informs the organism of tissue damage or injury.
Depending on the site of origin, nociceptive pain could be classified as somatic (based on skin, bones, connective tissue, muscles or joints) or visceral (caused by internal organs) pain.
Somatic pain is sub-divided into superficial pain (cutaneous pain) from the skin or mucous membranes (e.g. minor wounds, first degree burns) or deep pain derived from muscles, bones, joints, ligaments, tendons, blood vessels, fasciae (e.g. sprains, broken bones, myofascial pain). Deep somatic pain tends to be dull, whereas superficial pain is initially sharp and then later may become dull.
Visceral pain originates from the body's inner organs. Examples are abdominal pain or thorax pain. Its characteristic is dull pain which is difficult to locate. Visceral pain may radiate to the corresponding so-called head zones in the skin ("referred pain").