BED POSTS, FURNITURE legs, uneven flagstone, toys—the world is rife with foot-level obstacles. Far too many for even the coordinated among us to completely avoid. But if our feet and toes are destined to occasionally collide with these hard, inanimate objects, why must even minor stubbings cause major agony?
Yes, your toes seem to be among a select group of body parts that can be injured in a relatively insignificant way and yet still broadcast (at least for a minute or so) that they’ve been broken or in some other way irreparably damaged. It’s as if they’ve conspired to over-react to every stimulus they encounter. And in a way, that’s precisely what they’re doing. You should thank them, too.
No Brain, No Pain
To understand why, it’s important to first emphasize that pain is a perception; that is to say, it really is all in your head. Whether we’re talking about fire, a hammer, or that rock you just plowed your toe into, there’s nothing inherently painful in any given stimulus. Instead, it’s all about how your brain reads (and reacts to) the information it receives from a given stimulus.
Allan Basbaum, one of the world’s leading pain researchers and chair of the UCSF Department of Anatomy, likes to use a beauty analogy. “There’s nothing inherently beautiful in something,” he says. “And what’s beautiful in this culture isn’t necessarily beautiful in another, even if it’s the same object. Pain is the same way.” Your individual experience of pain ends up being a complex mixture of biology, psychology, and other cultural factors. It can be influenced by things like your state of mind, how much attention you pay to it, your memory of previous painful experiences, as well as the intensity of the stimulus and location of the insult.
In other words: Pain is sort of complicated. And we’re only now beginning to understand how the brain generates a particular pain experience. Thankfully, acute, or short-lived pain, which is what’s going on when you stub your toe, is a bit more straightforward. For most people, a stubbed toe doesn’t provoke vast range of pain experiences—it just hurts like hell.
Anatomy of Pain
Sudden and sharp pain serves a very useful purpose: It’s a warning, a protective biological signal urging you to stop whatever stupid thing you’re (intentionally or unintentionally) doing. Your experience of acute pain will depend mainly on the type and density of nerves in the region you injure, as well as the nature of the stimulus.
Take your pancreas or other viscera. You can actually cut into these parts of your body with little or no pain, explains Basbaum. Stretching them, on the other hand, is absolutely excruciating. That’s due to the type of innervation present and the specific stimuli those nerves react to. Similarly, if you took a hammer to an area like your stomach, it would certainly hurt, but it wouldn’t produce anywhere near the pain of taking one to your toe or finger. That’s because your stomach is both poorly innervated, and, for most people, pretty well protected with layers of tissue.