More than any other bodily injury, getting hit in the testicles is probably what every man dreads most.
睾丸被击中时痛苦恐怕是每个男人最可怕的噩梦，绝对没有什么比蛋疼更疼的事情了。
Of all the soft, fleshy spots on the human body, none register the same kind of incapacitating, end-of-the-world pain as the family jewels.
在人体所有的柔软部位中，在没有什么部位能像蛋蛋一样，能给你带来世界末日般无法阻挡的痛苦感觉了。
What causes such inconceivable pain? Well, for starters, a shot to the balls is just like any other physical strike to the body: because of nerves, it’s gonna hurt. Unlike most other parts of your body, though, your scrotum lacks protection in the form of bones, large muscle mass, and fat. The testes are just wee little glands, and they’re going to absorb the whole force of the blow all on their own.
这难以言说的痛究竟有何而来？首先，撞击睾丸和撞击身体其他部位一样，神经传递了痛觉。而与身体其他部位不同的是，你的阴囊无法得到来自骨骼、肌肉和脂肪的保护，睾丸也不过是个小小的腺体，却要吸收撞击产生的全部力量。
Another thing that makes a ball shot so painful is the same thing that makes almost every other sensation down there so much fun. Your groin has a ridiculously high number of sensory nerve endings, and such generous innervation makes good and bad touches alike very noticeable sensations
另一个让蛋疼如此深刻的原因其实也让你在某些和谐的场合给你带来很多的快感。你的阴囊上遍布了数量惊人的末梢神经传感器，如此丰富的神经分布阴囊对快感和疼痛都异常的敏感。
And the pain doesn’t just stay down there in the scrotum. It insists on radiating throughout the groin and up into the abdomen (and, psychically, out to every other dude standing within a few feet), leading to a weird stomach ache. This is the work of a phenomenon known as referred pain, which is when a sensation originating at one spot travels along a nerve root to other parts of the body and is perceived as happening there, too. It’s the same thing that’s going when you get an ice cream headache. In this case, the pain starts in your balls and travels up the perineal and pudendal nerves and the spermatic plexus, which cover real estate in the groin and abdomen, around the spine and even a little ways down into the anus, to make it feel like death has come for most of your lower body.
而且这种疼痛不是停留在阴囊里，它会从阴囊里蔓延开来直到腹部（甚至连站在你旁边的哥们也会觉得蛋疼），产生一种奇怪的胃痛。这种现象被称为牵涉性疼痛。这是由于产生于某处的感觉在传递途中经过了与另一部位神经相交汇的节点，从而使另一部位也产生了感觉。 冰淇淋头痛也是由这种现象导致的。蛋疼时，疼痛从蛋蛋里产生，经过了会阴、阴部神经，以及覆盖了阴囊和下腹部的生殖神经丛，通向脊椎，甚至有一点去了肛门，让你觉得自己的整个下半身都疼得快死了。
Location, Location, Location
位置，位置，要命的位置
Why is such a sensitive and delicate body part just hanging there in the open? The placement of the testicles is inconvenient, but absolutely necessary. The testes’ job is to produce sperm, and sperm are very fragile. They’re extremely sensitive to high and low temperatures, and must be kept away from the rest of the body and relatively exposed to maintain the right climate. They can handle human body temps for only one to four hours, or the average amount of time it takes them to travel through the female reproductive tract and fertilize an egg. Internal testes or any type of significant shielding for them would heat them up too much, too early and make them drop out of the race well before reaching the egg, rendering them useless.
为什么如此敏感的身体部位却暴露在外呢？睾丸摆在胯下是有些不方便，但无疑是必需的。睾丸的职责是生产精子，而精子相当脆弱。它们对温度的高低异常敏感，必需暴露在体外，保持相对的稳定的环境使精子存活。精子只能只能承受人类体温一到四个小时，一般来说是这两者的平均值，而精子要在这段时间内穿过女性的生殖通道，让卵子受精。内置的睾丸或其他围挡式的保护会使精子因为过热而过早地死亡，无法到达追求卵子漫漫旅途的终点。
The scrotum isn’t just a dumb sack swaying in the breeze, though. In deference to our genetic interests, our bodies subconsciously thermoregulate our balls by flexing the cremasteric muscle and drawing the scrotum up closer to the body when it gets too cold and dropping it when it’s hot. This optimized, on-the-fly sperm storage is precise enough that each testicle can be repositioned independent of its twin in order to get the temperature just right, explaining their sometimes asymmetrical dangle.
睾丸可不是迎风飘动的小麻袋，处于对基因的保护，我们的身体会自动地通过伸缩睾提肌进行温度控制。在外面太冷的时候身体会将睾丸收回肚子里，而在太热的时候把睾丸挂在外面。这种灵敏的精子存储系统相当精确，每一个睾丸都可以独立地调整自己的位置使温度保持在“刚刚好”的状态下，所以有时候蛋蛋会高低不齐地挂着。
This story was originally published by mental_floss
