ORIGIN OF ABDOMINAL PAIN



Afferent nociceptive (pain-sensitive) neurons from the viscera accompany bilateral efferent sympathetic neurons, eventually reaching spinal dorsal root ganglia and spinal sensory neurons. The latter also receive input from peripheral non-pain nerves, thus establishing the basis for re­ferred pain to extra-abdominal sites. Pain signals from the parietal peritoneum and the abdominal wall are carried by lateralized neurons in the so­matic sensory nerves. Abdominal organs are in­sensitive to stimuli such as cutting, tearing, and burning. Generally only three processes produce pain in the alimentary tract: (1) stretching or ten­sion in the wall of a hollow organ or the capsule of a solid organ as a result of forceful muscular contraction, muscle spasms, distention, or trac­tion; (2) inflammation with associated release of substances, such as bradykinin, prostaglandins, histamine, and serotonin, that stimulate or sen­sitize nerve endings; (3) ischemia, which releases noxious tissue metabolites.