QS Study

Irritation of an internal organ produces pain which is felt not in the same organ but in some somatic region sharing the same segmental innervations. This is called referred pain. This pain felt in a part of the body at a distance from the area of pathology, as pain in the right shoulder derived from the presence of a gallstone in the bladder. It is what happens when you suffer pain in a region of your body that is not really the original source of the pain signals.

Example of referred pain

  • Cardiac pain – Left shoulder and upper arm.
  • Appendix – Around the umbilicus.

Fig: Mechanism of referred pain

Mechanism of referred pain

Branches of visceral pain fibers make synapse in the spinal cord with some of the same second-order neurons (1 and 2) that receive pain signals from the skin. When the visceral pain fibers are stimulated, pain signals from the viscera are then conducted through at least some of the same neurons that conduct pain signals from the skin and the person has the feeling that the sensations originate in the skin itself.

Importance of referred pain

Important in clinical diagnosis because many visceral elements cause so other clinical signs except referred pain. The most general example of referred pain is when pain is felt in the left arm, neck or jaw of a person suffering a heart attack, while they often have no feelings of pain in the chest region itself.