I inherited a lot of good traits from my parents, but athletic ability isn’t one of them. So when my son asked me to play soccer the other day, I agreed only reluctantly.

At one point, when I tried to get the ball away from him, I kicked wildly and hit the back of his sneaker instead of the ball. At the moment of impact, I felt a searing pain in my right big toe. I knew I hadn’t broken anything, because it wasn’t a deep, “bone-y” sort of pain. It was a sharp pain, as if my toenail was being pulled off.

When I examined my foot, I saw a red, swollen area where the nail reaches the end of the toe. My first thought was: Why didn’t I notice that when I put on my sock three hours ago? My second thought was: This explains why my toe has been bothering me for the past week. It was painfully clear that I was the proud owner of an ingrown toenail.

Nails are made from keratin, which is the same protein that gives hair and skin their strength. Nails are stronger than hair and skin because the density (thickness) of the keratin is greater. Keratin is the same substance found in a horse’s hooves and a lion’s claws.

Like our other body parts, nails are more complicated than they first appear. The part that we normally think about (and that some of us paint) is dead tissue called the nail plate. When you cut your nails, it doesn’t hurt because the nail plate doesn’t contain nerves.

The matrix lies underneath the nail plate. It produces the cells that make the nail, and it contains nerves. If you cut your nails too close and nick the end of the nail bed (the tissue under the nail), an “ouch” is in your future.

The lunula, which is most noticeable on the thumb, is the crescent-moon-shaped lighter area that’s closest to the knuckle. The cuticle is the border of hardened skin behind the lunula.

As new nail cells are made, they push the nail plate forward. Fingernails grow about one-tenth of an inch per month. That’s four times faster than toenails. The white spots commonly seen on fingernails are caused by minor trauma (injury) to the nail plate, not by a calcium or vitamin deficiency.

Ingrown toenails are more common than ingrown fingernails. They occur when the nail grows into the fleshy part of the toe. When that happens, the tissue will hurt just as if you had a big splinter. Ingrown nails often become infected, because the nail pushes through the skin, allowing bacteria to enter your body.

The most common ways you can increase your risk of getting ingrown nails include wearing tight-fitting shoes, cutting your nails too short and picking your nails.

The best way to treat ingrown toenails is to prevent them from happening in the first place. Wear comfortable shoes, and cut your nails (especially on the big toe) so the nail extends a little bit past the end. If one of your nails becomes ingrown, have your mom or dad call the doctor, because you might need an antibiotic if the tissue gets infected.

Bennett is a Washington pediatrician. His website, www.howardjbennett.com, includes past KidsPost articles and other cool stuff.