Why does hitting your funny bone feel so horrible? - Cella Wright

翻译人员: Tianyun Liu 校对人员: Gia Hwang

Whatever you were doing, there was no way to anticipate what came next.

无论你在做什么，

都无法预测接下来会发生什么。

The back of your elbow smacked against a hard surface

手肘后部撞到坚硬的表面，

and the impact sent a sensation so distinctly disquieting

冲击给手臂带来了非常奇怪的感觉，

shooting down your arm that it took several moments to regain composure.

让你花了好一会儿才平复下来。

So, why does hitting this spot on your elbow—

为何撞到肘部俗称鹰嘴的这个部位

often referred to as your funny bone— feel so weird?

感觉如此奇怪呢？

Well, to start, your elbow is one of the most complicated joints in your body.

首先，肘部是你体内最复杂的关节之一，

It's where your upper arm bone, the humerus,

是你的上臂骨即肱骨

meets the two bones of your forearm.

与前臂两根骨头交汇的地方。

Three main nerves run through your elbow.

三条主要神经穿过肘部，

One of them, the ulnar nerve, is particularly relevant for our purposes.

其中，尺神经与我们所讲的尤为相关。

Your ulnar nerve is composed of both sensory and motor nerve fibers.

尺神经由感觉神经纤维 和运动神经纤维组成，

It extends from your spine to the tips of your fourth and fifth fingers,

从脊柱延伸到第四和第五手指末端，

providing them with sensation along with swaths of your forearm and hand.

为它们以及前臂和手提供触觉。

So, say your little finger gets crushed by a car door.

假设你的小手指被车门挤断了，

Sensory receptors in your pinky finger's tissues

小指组织中的感官受体

register that unfortunate information

会记录这个不幸消息，

and send electrical impulses up the ulnar nerve,

并将电脉冲发送到尺神经，

which are then processed in your central nervous system.

然后在中枢神经系统中进行处理。

This leads to the perception of acute, sharp pain,

这会导致急性剧烈疼痛，

followed by aching.

然后是隐隐作痛。

So that's how your ulnar nerve generally works.

这就是尺神经的工作原理。

But your elbow has an anatomical quirk that leaves your ulnar nerve vulnerable

但肘部有一种解剖学上的特殊现象，

使得尺神经易以不同的方式被激活。

to getting activated in a different way.

Along almost all of its length, your ulnar nerve is protected,

尺神经几乎全长都受到保护，

hidden beneath muscle, fat, and bone.

隐藏在肌肉、脂肪和骨骼之下。

Thankfully, this is generally true of your nerves.

谢天谢地，神经通常是这样被保护。

But when your ulnar nerve reaches your elbow,

但是，当尺神经到达肘部时，

it runs beneath the bony bump at the bottom of your humerus,

它在肱骨底部的骨质凸起（即内上髁）

named the medial epicondyle,

下方运行，

and it passes through a tunnel of ligament and muscle tissue

并穿过一条由韧带 和肌肉组织组成的通道，

called the cubital tunnel.

即肘管。

When you bend your elbow,

当你弯曲肘部时，

your ulnar nerve gets flattened against the medial epicondyle

尺神经会被压扁在内上髁上，

and the protective tissue in the area gets displaced,

该区域的保护组织就会移位，

bringing the nerve especially close to the skin's surface.

使尺神经特别接近皮肤表面。

In this position, the ulnar nerve is covered only by skin

在这个位置，尺神经

仅被皮肤和肘管韧带组织覆盖，

and cubital tunnel ligament tissue,

making it perhaps the longest area of semi-exposed nerve in your body.

这可能是体内最长的半裸神经区域。

So, when the area is struck at the right angle with enough force,

因此，当用足够的力量以 正确的角度击中该区域时，

something interesting happens.

会发生一些有趣的事情。

Instead of the sensation simply activating peripheral receptors

这种感觉不是简单地激活

that send electrical signals along your ulnar nerve,

沿着尺神经发送电信号的外周感受器，

the nerve's fibers are stimulated directly.

而是直接刺激神经纤维，

This is why hitting your so-called funny bone hits different.

这就是为何撞到鹰嘴会感觉大不同。

The exact mechanisms aren't yet fully understood.

确切机制尚不完全清楚，

But the impact alters the ulnar nerve's signaling,

但撞击改变了尺神经的信号传递，

perhaps by causing a proliferation of nerve signals,

可能导致神经信号的增殖，

leading to that intense pins-and-needles sensation

从而产生强烈的针刺感，

called transient paresthesia,

这种感觉被称为短暂性麻痹，

which radiates down the length of your arm.

并向手臂下方放射。

In rare cases, whacks to this special spot

极少数情况下，对这个特殊部位的重击

have led to temporary loss of consciousness,

会导致你暂时失去知觉，

perhaps because a hard enough strike could disrupt nerve signaling

这可能是因为足够猛烈的打击

会中断神经信号和血液流动。

and blood flow.

In addition to these more immediately distressing moments,

除了这些更直接的痛苦之外，

regular bent-elbow activities are thought to put pressure

长期来看，经常性的弯肘活动

on the ulnar nerve over time.

会对尺神经造成压力。

Ulnar nerve entrapment is a relatively common condition.

尺神经卡压是一种相对常见的疾病，

It happens when the ulnar nerve becomes compressed and obstructed,

它发生在尺神经受压和阻塞时，

most commonly with the cubital tunnel.

最常见的是肘管处。

The result of this chronic ulnar nerve pain can be persistent paresthesia,

这种慢性尺神经疼痛的结果可能是

持续性麻痹以及前臂和手部无力。

as well as weakness in the forearm and hand.

In the hopes of preventing such conditions,

为了预防这种情况，

doctors recommend conscientious elbow usage.

医生建议谨慎使用肘部，

That includes stretching your arms and straightening your elbows,

包括伸展双臂和肘部，并适当休息，

and generally taking breaks that help provide regular relief

这有助于定期舒缓

and maximal blood flow to your ulnar nerve.

和最大限度地增加尺神经的血流量。