Referred pain is felt at an area where the viscus was once situated in embryonic life.
egs. #1. Diaphragmatic pain is felt at shoulder region (diaphragm was situated at the root of the neck)
#2. Testicular pain is felt at abdomen (testes descended from abdomen)
#3. Renal pain is felt in loin (kidney ascended up)
etc.
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Have clinicians ever come across a case where the 'antiquated' embryonic viscus referred pain hypothesis was proven wrong? Convergence and subliminal fringe theories obviously make a lot more sense.
As a medical student, I was taught the same - pain from a viscus is referred to its embryologic origin. I am not aware of any new theories that has convincingly disputed this hypothesis. I am interested if anyone knows.
Background: I treat pudendal neuropathy and the patients often have additional peripheral neuropathic pain generators. Patients have central sensitization. The sympathetic innervation of abdominal and pelvic viscera is referred to the thoracolumbar junction region of the spinal cord. Viscera lack somatic sensory innervation.
Thus patient with pudendal neuropathy may have colitis symptoms, irritable bladder, persistent genital arousal, etc.
Moreover, pressure on thoracic or abdominal cutaneous nerves at the rectus border can refer pains to viscera. Left T-8 caused a "tube of pain" to the vagina. T-10 caused urge to void. T-12 caused pain in the cervix.
These are but a few examples. The "pinch roll" maneuver of Maigne (TLJ syndrome) can cause pains in any viscera in various patients.
I would consider the sympathetic innervation, developing in the fetus, drives the focus of the visceral pain to the cord level of somites that produce the viscus.
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