A dentist about to start root canal work on a woman suddenly feels her hand firmly grasping his testicles. As he stares at the women openmouthed, she says with a smile: ‘Let’s promise not to hurt each other!’ Pain in the testicles is excruciating, but hard to understand even for doctors. The fact is that nerve provision in the testes is complicated. The autonomous, sympathetic nerve supply derives from the spinal segments of the tenth and twelfth vertebrae. These nerves run parallel with the blood vessels. They penetrate the fibrous sheath surrounding the testicles (tunica albuginea) and continue their course among the lobules
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where the sperm cells are produced. Their most important function seems to be to affect the contraction or otherwise of the smooth muscular tissue in the tunica albuginea. The nerve endings governing sensation in the testicles are located in the same compartment as the Leydig cells. If the skin of the scrotum and the tunica vaginalis are anaesthetized and the testicle is then injected with a physiological salt solution, pain is felt not in the scrotum, but instead deep down in the abdomen. This is probably referred pain, deriving from the autonomous nerve supply.
The somatic, or non-autonomous nerve supply is through the nervus genito-femoralis and derives from the spinal segments of the first and second lumbar vertebrae. The nerve branch to the interior of the scrotum runs first to the testicular muscles, and passes right through them before continuing to the tunica vaginalis and tunica albuginea of the testicles. If in the course of an operation this nerve is severed, whether or not deliberately, henceforth when the testicles are squeezed hard pain will be felt only deep in the groin. With spinal anaesthesia up to the level of the first lumbar vertebrae ‘testicle sensation’ also disappears. The above findings indicate that only with intense stimulation, for example hard squeezing, does autonomous nerve pain occur: dull, nauseating pain that is difficult to localize. If pain is clearly felt in the scrotum, it is conducted via somatic nerves.
Referred pain in the scrotum may be the result of, for example, a kidney stone that has descended into the urethra, a weak spot in the inguinal artery, a minute hernia in the groin that is not yet visible or wear and tear on the spinal column.