Final answer:
Pelvic viscera referred pain is felt in dermatomes T11-L2 for the urinary bladder and T10-L1 for the kidneys, commonly in the lower abdomen, groin, and back. Referred pain is due to the convergence of visceral and somatic fibers at the same spinal levels causing the brain to misinterpret the site of pain.
Step-by-step explanation:
Referred pain from the pelvic viscera due to the pelvic pain line refects the phenomenon where pain from internal organs is perceived in areas distant from the actual site. The dermatomes associated with referred pelvic pain differ for the different pelvic organs but tend to be in the lower abdominal regions, groin, and sometimes the back. For instance, both male and female urinary bladders, when experiencing visceral pain, may refer pain to the T11-L2 dermatomes, which include the lower abdomen and groin. Similarly, the kidney is associated with the T10-L1 dermatomes, potentially referring pain to the back and sides of the body.
The pelvic pain line demarcates the different innervation above and below it; the upper viscerae above the pain line send their sensation through sympathetic fibers, while the lower viscerae use parasympathetic fibers. Since visceral pain fibers often converge with somatic fibers at the same spinal nerve levels, the brain may misattribute visceral pain to somatic regions associated with certain dermatomes; hence, the conception of referred pain arises.