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msnbc.com contributor
updated 11/9/2010 8:33:51 AM ET 2010-11-09T13:33:51

As a constant klutz who jokes about trading her wardrobe for “full-body padding,” Lauren Gard can’t even water the flowers without harming herself.

While hosing down a garden several weeks ago, Gard managed to imbed a sliver of the metal nozzle in her thumb. The wound throbbed for hours — yet it was just another nick in a life laced with stinging but otherwise harmless scrapes.

“I’m a classic case of someone who should surround herself with round-edged furniture,” said Gard, a public relations professional in San Francisco.I try to think of the bruises that often dot my legs ... as my own unique tattoos.” Her blur of bumps and bangs hasn’t produced so much as a hairline fracture. But that doesn’t mean all her slices and stubs haven’t flooded Gard’s nervous system with torrents of pain vibes.

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The tiniest injuries, doctors agree, can often cause maximum pain: ramming a pinky toe into a chair leg, pinching a finger in a door, twanging an elbow on a hard corner, or suffering, inch-for-inch, perhaps the most excruciating superficial trauma, the dreaded paper cut.

So we’re not being pampered whiners when we yelp after kitchen-knife piercings or moan about our heel blisters? Some of the cruelest cuts truly are the smallest?

“Oh yeah, totally,” said Dr. Amy Baxter, a pediatric emergency physician in Atlanta. “Part of it really is because of the location.”

This is all about your internal wiring. Feet, hands and lips are disproportionally represented in swaths of the brain that recognize touch and injury — and in the thicket of neurological pathways that run between your brain and those sensitive spots. Fingertips and toes are highly saturated with nerve endings to boost dexterity and help us balance while walking. Yet these receptors also flash to the brain urgent signals of harmful stimuli like fiery heat or skin punctures. The brain interprets those messages as pain and commands hands or feet to pull back.

“The more pain receptors, the more intense the pain,” said Dr. Mauro C. Romita, a plastic surgeon in New York City. “That’s why a burn on the hand and fingers is more painful than a sun burn on the back or nose.”

Because hands and feet are busy appendages, they’re most vulnerable to tiny perils like paper cuts and shin barks, and to their aching aftershocks.

“You keep using these body parts, you keep reinjuring them – ‘Ow, ow, ow!’ ” Baxter said. “As the body heals, the white blood cells flooding to the area make it swell a little, thus it’s more tender, thus the little dings hurt even more.”

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Rubbing an injured elbow really does help
But the nerve schematics that make you feel pain also explain why your first instinct after an injury is often to massage a smacked elbow or blow on a burned finger. Scientists call this reaction the “Gate Control Theory.”

Proposed by in the 1960s by British neuroscientist Patrick Wall and Canadian psychologist Ronald Melzack, the notion is that you can relieve pain by sending new neural signals to the brain from the same, freshly wounded location. The brain’s interpretation of the pain can, therefore, be slightly altered and — hopefully — dulled. Based solely on this theory, Baxter, the Atlanta doctor, developed (with the aid of a federal grant) a new product called “Buzzy.” Thevibrating cold pack is placed on a child’s arm before an injection, confusing the nerves and distracting the brain’s attention away from the poke. The primary idea is stop kids from fearing inoculations. “Buzzy” is now being used in about 100 hospitals, Baxter said, including the Mayo Clinic.

“I absolutely believe in (the) Gate Control Theory,” said Dr. Reza Ghorbani, president and medical director for the Advanced Pain Medicine Institute near Washington, D.C. “Rubbing a banged knee activates some nerve endings which, in turn, doesn't let some other painful signals get to the brain.”

Of course, there are those folks who furiously stroke an injured arm or leg, and those who barely flinch after sustaining a sock or smack. Again, our personal neural net is the reason.

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“We’re all wired differently,” Ghorbani said. “Injured nerves may fire stronger or more frequently in one person than other. This is purely related to our genes and how they make us so different from one another ... Perception of pain in the brain — when these signals reach us — is different among everyone. This affects our mental condition and how we deal with pain (and gives us) low or high pain tolerance.”

Pain thresholds differ, of course, even among doctors. For Ghorbani, the worst everyday wound is the accidental elbow blow — the shot to the “funny bone” which jolts your arm with a weird, buzzing feeling. Inside the elbow joint, the ulnar nerve sits is close to the skin and, consequently, is exposed to danger. That’s the nerve that fires after an elbow is slammed causing — as Ghorbani describes it — “That sharp, shooting electrical pain radiating to my fingers!”

According to Dr. Tom Potisk, a chiropractor near Milwaukee, the worst pain can come in the most miniscule slashes. Our skin’s outer layer — roughly the top eighth inch — contains the most nerve endings. So deep gashes, Potisk said, may not trigger as many pain receptors as surface nicks.

He knows this first hand. Last summer, while fishing with his son on their home pond, Potisk caught a bluegill. As the doctor released the hook from the mouth of the fish, the bluegill flopped, freeing the hook which dug directly below the nail on Potisk’s left index finger.

“I quickly pulled it out, but only after a scream of pain, and a lesson about just how sensitive and close those pain receptors are to the skin surface,” Potisk said. “Now I know why the Japanese used that as torture during World War II.”

Bill Briggs is a frequent contributor to msnbc.com and author of the forthcoming book, “The Third Miracle.”

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