Mechanism of Referred Pain. Figure 48-5 shows the probable mechanism by which most
pain is referred. In the figure, branches of visceral pain fibers are shownto synapse in the spinal cord
on the same second-order neurons (1 and 2) that receive pain signals from the skin. When the visceral
pain fibers are stimulated, pain signalsfrom the viscera are conducted through at least some
of the same neurons that conduct pain signals from the skin, and the person has the feeling that the
sensationsoriginate in the skin itself.
Visceral Pain Pain from the different viscera of the abdomen and chest isone of the few criteria
that can be used for diagnosing visceral inflammation, visceral infectious disease, and other
visceralailments. Often, the viscera have sensory receptors for no other modalities of sensation besides
pain.
