To me it seemed that the brain whose owner has just poked a finger in his eye should register something else, like a grievance with its union. Nevertheless I tried a tentative poke and indeed got the promised flash of light. The reason the flash was on the opposite side of the eye has to do with the way the brain processes an image. In ordinary vision, the lens focuses incoming light in such a way that it flips an image upside down and backward. When the eye inverts an image, the brain knows that it must automatically compensate by flipping the picture back the right way.
Though the delicate touch I gave my eye yielded just one small flash, Wolfe said that when the eye is struck by something less forgiving—like a swinging door or Ira Blitz—many parts of the retina may be stimulated simultaneously, giving rise to a whole constellation of light. Sometimes the retina is so mechanically stimulated that a large portion of the visual cortex of the brain begins firing at once. This is what happens when you rub your eyes and your field of vision is filled with that undulating checkerboard.
Neurophysiologists have discovered that particular cells in the brain are responsible for registering particular shapes (horizontal or vertical lines, for instance), Wolfe said. If you rub your eyes too much, you send random, meaningless noise to your brain, and all the cells for all the shapes begin screaming at once. At Wolfe’s instruction, I commenced a very vigorous rub and got the promised checkerboard. To me this was enough retinal recreation for one day, so before Wolfe got me too involved in his other experiments—including the wiggle-the-eyeball and misalign-the-eyes tests—I thought it best to try my own exercise, known as hang-up-the-phone.
With my eyes thus under my belt, I went off to see what I could learn about other fistfight injuries. Perhaps the most dramatic of these is the punch in the stomach—or, specifically, the punch in the solar plexus. As most people know from experience, the solar plexus is that area just below the rib cage which, if hit just right, can cause you to feel as if you’ve had the wind—as well as the rain, the snow, and at least one kidney—knocked out of you. The term solar plexus comes from the Latin solaris, for “Try not to get punched here,” and plexus, for “We’re not kidding.”
My introduction to the perils of the solar plexus came when I was 9 or 10 years old and got into a fight with my older brother after he gave me a model of the Mayflower ship and then tried to take it back. Sibling common law usually grants an older brother unilateral rights to seize possession of any toy at any time for any reason. On this occasion, however, I had made it a point to touch a black object and recite, “Touch black, no back,” an incantation that the Supreme Court had ruled binding in 33 states, the District of Columbia, and Guam. My brother was evidently not up on recent court rulings, and a scuffle ensued, resulting in my sustaining a severe blow to the solar plexus. The loss of breath was sudden and total. I’ve never been entirely certain how long it took me to get my wind back, but family members tell me I was more or less myself again by my sophomore year in high school.
Excruciating as the experience was, however, it turns out that it was a largely harmless one. Getting the wind knocked out of you is analogous to jamming your funny bone, says physician Chris Freyberg, director of the emergency department at the Southern Arizona VA Health Care System in Tucson. It’s a temporary paralysis of the diaphragm caused by trauma to the phrenic nerve. This nerve descends from the upper part of the torso and forks off to make contact with the diaphragm on both sides. When the solar plexus is struck, the diaphragm sustains a concussion, which it transmits to the phrenic nerve. The nerve shuts down temporarily and can’t make the diaphragm contract. To the surprise and considerable disappointment of the victim, he finds he can’t draw his next breath. The worse the blow, the longer the shutdown.
Almost as sensitive to injury as the solar plexus are the exquisitely delicate nose and ears. As you know if you’ve ever flipped through a professional boxing magazine, strange, almost Picasso-esque things can happen to the face that gets in the way of too many punches. The common cauliflower ear, which gives so many professional fighters that always-fashionable fresh crudité look, is caused by a blow or other trauma to the outer ear, leading to the accumulation of blood between the cartilage and its fibrous covering. This coagulated blood then blocks the flow of new blood to the cartilage, resulting in tissue death and the buildup of scar tissue. Treatment involves draining the ear, removing the scar tissue, repositioning the fibrous covering, and giving serious thought to seeing a good career counselor.
Even if you’ve never stepped into a boxing ring, you know that almost any bump or blow can do serious damage to the proboscis, causing immediate bleeding and agonizing pain and eventually turning even a modest button nose into something closer to a buttonhook. “That’s probably why, instinctually, people have been taught to punch other people in the nose,” Freyberg says. “It’s humiliating in the sense that it’s probably the most painful spot on the face, can make you look physically deformed, and is probably the spot on the face that will become most bloodied. It’s more defaming than anything else.”
Though such fragility would make the nose seem a shabbily designed organ, it is in fact an elegant one; its very elegance is what makes it so delicate. The entire face is highly vascularized and innervated, Freyberg says. For all the different ways it has to move and all the jobs it has to do, it needs lots of blood and nerve endings. The nose, in particular, has to detect subtle smells, and for that it needs to be rich in nerves. However, that also makes it sensitive to pain. Similarly, mucous membranes are active tissues and thus have to be rich in blood, but that means an injury is going to cause them to bleed copiously.