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where blood flows back to the heart. On a level with the internal ring of the inguinal canal this complex becomes the drainage vein ( vena spermatica interna ). On the right-hand side this flows directly into the inferior vena cava, and on the left into the renal vein. This division is the reason why varicose veins in the scrotum, varicocele, are much more common on the left than on the right.
    Lymphatic drainage from the testicles is in the first instance into lymph glands behind the abdomen and not, as many people think, into glands in the groin. That fact is particularly important in the treatment of testicular cancer. The lymph glands in the groin do, however, form part of the drainage system of lymph from the skin of the scrotum. In the past cancer of the skin of the scrotum was very common among chimney sweeps and coalmen, who had soot and coal dust more or less continually in their crotch. Today cancer of the skin of the scrotum is extremely rare.
    Nerve supply
    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 open-mouthed, 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 29

    m a n h o o d
    The plexus
    pampiniformis
    and the vena
    spermatica
    inferma.
    Arteria testicularis
    Vena spermatica
    interna
    Plexus
    pampiniformis
    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 auto -
    nomous 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.
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    t h e t e s t i c l e s a n d t h e s c ro t u m The epididymis
    The sperm-forming tubes in a testicle discharge into a kind of transit depot. Between six and eight ducts lead to the epididymis. In the epididymis those ducts merge into a single tube. While the sperm-forming tubes in a testicle have a combined length of 250 metres, an epididymis is a duct of approximately 6 metres in length. The epididymis curls in a comma-shape behind the testicle. One can distinguish a head ( caput