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Referred pain
- pain felt away from its original actual site.
- visceral pain is not felt in the viscus but in some
somatic structures of the body surface, which are
supplied by the same dorsal roots that supply the
diseased viscus.
- deep somatic pain may also be referred.
Examples of referred pain
1- cardiac pain:
- angina pectoris (= heart attack) or ischemia of
cardiac muscle leads to stimulation of pain
receptors.
- impulses pass into the spinal cord through the
2nd & 5th thoracic spinal nerves.
therefore, cardiac pain is referred mainly to the
base of the neck, shoulders , left arm &
retrosternal.
2- biliary & gall bladder pain:
is referred to the midepigastrium & to small area
at the tip of the right scapula.
3- renal pain:
pain from the pelvis of the kidney or ureter is
referred to the inguinal region, testicle & scrotum.
4- inflammation of appendix:
pain from inflammed appendix is referred to an
area around the umbilicus.
Mechanism of referred pain:
convergence - progection theory
- pain impulses from skin & diseased viscus are
transmitted by 2 afferent neurones which converge
on the same cells in the S.G.R., thalamus or
sensory cortex.
- visceral pain is projected to the skin area because
the sensory cortex is accustomed to receive pain
sensation from the skin which is dominant.
