The human body is an amazing thing. For each one of us, it's the most intimate object we know. And yet most of us don't know enough about it: its features, functions, quirks, and mysteries. Our series The Body explores human anatomy, part by part. Think of it as a mini digital encyclopedia with a dose of wow.

You can thank your buttocks for a number of physical actions you take every day, from moving your hip and thigh during walking or running, to rising from a sitting position, climbing, and even just standing upright. While lack of exercise can make these muscles soft, in general they're some of the hardest working muscles in your body. To learn more, Mental Floss spoke with Clifford Stark, medical director of Sports Medicine at Chelsea in New York City, and Vivian Eisenstadt, an orthopedic and spine specialist in physical therapy in Los Angeles. Here are six quick facts we picked up about the glutes.

1. WHEN IT COMES TO THE BOOTY, BIGGER MIGHT BE BETTER.

Your glutes are your body's largest and most powerful muscle group, Stark tells Mental Floss. Your powerful buttocks are actually comprised of three gluteal muscles: the gluteus maximus, gluteus medius, and gluteus minimus, often shorthanded to "the glutes."

"They are extremely important in preventing all sorts of injuries," Stark adds. Many injuries, from hips to knee, stem from weak gluteal muscles. It's important to keep your glutes strong—but not tight.

2. IF YOU'RE NOT BORN WITH IT, YOU CAN PAY FOR IT.

In 2016, 4251 people in the U.S. got a butt lift, and another 2999 got butt implants, according to the American Society of Plastic Surgeons' 2016 Report [PDF]. These numbers make sense, because according to the professional organization, butt implants were the fastest growing type of plastic surgery in 2015. Yet while butt surgery may be increasingly popular, it still hasn't cracked the top 5 of cosmetic surgical procedures (breast augmentation, liposuction, nose reshaping, eyelid surgery, and facelift, in that order).

3. WHY DO WE CALL A BARE BUTT A "FULL MOON"?

In the Ming dynasty in China, bare buttocks were seen as quite erotic and they were often compared to a full moon, perhaps because of their pert roundness.

4. VICTORIANS WERE REALLY INTO EROTIC SPANKING.

While spanking has been proven bad for kids, it may be good for your sex life. Victorians were particularly obsessed with "erotic spanking." According to Deborah Lutz, author of Pleasure Bound: Victorian Sex Rebels and the New Eroticism, "something like 50 percent of the pornography of the time was flagellation pornography," she told Salon. One prevailing theory suggests that the practice has its roots in the upper-class men who as children had attended private schools, where a common punishment was to be whipped in front of their classmates with birch switches. "Any schoolboys who wanted to could come and watch. For many of these boys, of course, it was traumatic, but for other boys it's an erotic experience. It developed into this masochistic eroticism," Lutz said.

5. BACK PAIN MAY ORIGINATE IN YOUR BUTTOCKS.

"A little-known fact is that strengthening your buttocks helps decrease back pain," Eisenstadt tells Mental Floss. "While physical and occupational therapists know this, many people are not aware and increase risk of injury by neglecting this important muscle." In her practice, when people come in complaining of back pain, she checks out their butts first.

6. A SMALL NUMBER OF PEOPLE HAVE THIS UNUSUAL POSITIONING OF THE SCIATIC NERVE.

"Sciatica is a laymen's term for pain down the leg," says Stark. The sciatic nerve typically lies right on top of the piriformis muscle, a small muscle that lives deep in the buttock, behind the gluteus maximus. For a certain percentage of the population, however, he says, the sciatic nerve sometimes pierces right through the muscle. Those people are especially prone to sciatic pain, he says: "All it takes is a spasm to cut off that nerve."