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10 Things You Might Not Know About the Elbow

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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.

Unless you bang your funny bone or regularly play tennis, it's unlikely you spend a lot of time thinking about your elbow. But without this crucial joint, many daily activities would be impossible, explains Anand Murthi, attending orthopedic surgeon and chief of shoulder and elbow surgery at MedStar Union Memorial Hospital, in Baltimore, Maryland.

1. THE ELBOW IS MORE COMPLEX THAN IT MAY SEEM.

The elbow may seem small, but it requires three bones to make its simple hinging action possible. The humerus is a long bone that runs from the shoulder socket to the radius and ulna. (And yes, there's a school of thought that believes your "funny bone"—actually your ulnar nerve—is named as a play on the word humorous.) The radius is one of the two forearm bones, running down from the elbow to the thumb side of the wrist. Lastly, the ulna stretches away from the pinkie side of the wrist. Thanks to those three bones, your arm can hinge—making it possible to do a bicep curl, lift a bag, or rotate your hand.

2. IT'S ALL HELD TOGETHER BY A KEY LIGAMENT, AS INJURED ATHLETES KNOW WELL …

The bones of the elbow are connected by numerous tendons and ligaments, including the ulnar collateral ligament, a fibrous tissue that connects the humerus to the forearm bones. This tendon is both important and vulnerable. When it ruptures or tears, you feel severe pain and can sometimes even see bruising on the inside of your arm. It's a surprisingly common sports injury, plaguing players of baseball, football, ice hockey, and golf. The other major ligament in the joint is called the radial collateral ligament. Located on the outside of the elbow, it prevents excessive extension of the elbow, and is less prone to injury.

3. … BUT THAT'S NOT THE ONLY VULNERABLE PART OF YOUR ELBOW.

At the lower end of the humerus are two rounded protrusions called epicondyles, which flare out from the bone. This is where muscles attach. The upper end of the ulna also has two protrusions, called the olecranon—which forms the pointy part of the elbow—and the caronoid process, a projection from the front of the ulna. Bone fractures, especially in children, often occur at these epicondyles, and are the most common short-term injuries of the elbow. Certain kinds of arthritis, especially in older patients with osteoarthritis, can also cause such severe degeneration here that an elbow replacement is necessary. (Since bones become more brittle as we age, it's wise to take steps to prevent falling or stumbling, as elbows are among the most likely casualties.)

4. TRAMPOLINES ARE COMMON ELBOW-BREAKERS.

Children love the thrill of a jump on the trampoline, but Barbara Bergin, an orthopedic surgeon in Austin, Texas, tells Mental Floss that she sees numerous fractures around the elbow in kids from doing just that. It's so common to break elbows and wrists this way, the American Board of Pediatrics warns against trampolines.

5. TWENTY-THREE MUSCLES GIVE YOUR ELBOW STABILITY AND FLEXIBILITY.

But the major muscles involved in bending your arm are the triceps—on the back of your arm—and biceps, on the front of your arm. Your many smaller flexor and extensor muscles allow you to move your wrists and fingers and rotate your forearm.

6. YOU DON'T HAVE TO PLAY TENNIS TO GET TENNIS ELBOW.

One of the most common conditions of the elbow is called "tennis elbow"—or lateral epicondylitis. Tennis players are prone to it, but it can be caused by any repetitive bending and flexing of the elbow, says Bergin. It's a painful degeneration of the tendons that attach to the bone on the outside of the elbow. It's so common, she says, "I probably see tennis elbow every day in my office." If the condition should strike you, Bergin says, "It's critical to stop doing whatever hurts. It will not get better if you continue to participate in whatever activity is causing pain." Full and total healing is required before you can return to the activities that gave you the condition in the first place.

7. IF IT GETS BAD ENOUGH, YOU MAY NEED "TOMMY JOHN" SURGERY.

When major league pitcher Tommy John injured his ulnar collateral ligament in 1974, his doctor opted to try a unique surgery to replace the deteriorated ligament with a tendon from somewhere else. Though the surgery can require a full year's recovery time—in Tommy John's case, it was nearly two and a half years and two surgeries—it's since become a time-tested method to repair this damaged ligament. Murthi tells Mental Floss, "New research on repairing the medial collateral ligament (versus reconstructing it) may lead to earlier recovery for Tommy John surgery. Also new treatments for articular cartilage damage, ligament reconstruction, and joint sparing techniques are evolving."

8. BUT IT'S HARD TO OPERATE ON YOUR ELBOW.

The elbow's close proximity to important blood vessels and nerves in your hand and arm make it a challenge to perform surgery on, Murthi says: "Careful, precise surgery is required to provide a good outcome. Often, rehabilitation with a skilled therapist is crucial to a good recovery." Currently, many operations are performed arthroscopically, so that surgeons can see all the various components as they make delicate maneuvers.

9. IF YOU HAVE TO GET AN AMPUTATION, HOPE FOR ONE BELOW THE ELBOW.

Should you have the misfortune of losing part of an arm, it's better to lose the parts below the elbow, Bergin says. This helps you maintain a range of motion and allows you to better manipulate a prosthesis. Fortunately, upper extremity amputations are rare and almost always result from accidents, as compared to lower arm amputations, which are often caused by some form of vascular disease.

10. EVEN JUST READING A BOOK CAN CAUSE AN ELBOW CONDITION.

While you may be tempted to read that latest hefty bestseller late into the night, if you're keeping your elbows bent in a sitting position for too long, you can get a case of ulnar neuritis, inflammation of the ulnar nerve—which can lead to numbness or weakness of the fingers and hand. Bergin warns, "It's much more common now than it used to be because we sit around for hours at a time on our phones." If you experience a "little tingly feeling in the pinky and fourth finger," she says, you've probably got a case. Her recommendation is to take as many breaks with your arms straight out as you can. Switch to a kindle or laptop that you can prop up to read at night. Be conscious of your ergonomics when you drive, type, and use your electronics.

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The Body
7 Surprising Facts About the Chin
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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.

The humble chin, that bony protrusion at the bottom of your face, is a mysterious little body part that is a surprising source of controversy among researchers. Though popular culture derives great meaning out of how "strong" or "weak" chins are, very little science backs that up. Here, however, are seven actually scientific facts, which Mental Floss learned from experts, about the chin.

1. RESEARCHERS DISAGREE ABOUT THE PURPOSE OF A CHIN.

The most interesting thing about the chin, according to Faisal Tawwab, a family practice doctor with Multicare Physicians in Orlando, Florida, is that there is no precise answer as to why we even have one. "Prevailing theories include assistance with speech, to protect the jaw from chewing, as a way to measure attractiveness when seeking a partner, or a combination of all three," he tells Mental Floss. "Research to find the true purpose of the chin is ongoing. There are critiques around all of the current prevailing theories."

2. IT MIGHT HELP THE JAW STRESS LESS.

The chin may have evolved to protect the jaw from the unique stresses of shaping our mouths to form language, according to a 2007 study in the journal Medical Hypotheses. Your chin may help bear some of the muscle load of chewing and speaking (a valid reason to want a strong one).

3. THE CHIN IS CRITICAL TO CHEWING.

"The most important function of the chin is mastication [chewing] and lip continence," Francesco Gargano, a board certified plastic surgeon with The Plastic Surgery Center in New Jersey, tells Mental Floss. "Several muscles insert into the chin and are part of the occlusal plane," the space between your teeth when the mouth is closed. Research supports this theory, suggesting that the chin "helps buttress the jaw against certain mechanical stresses," including chewing, which produces a great deal of force.

4. CHINS MAY HAVE HELPED OUR ANCESTORS CHOOSE A MATE.

A more recent theory is that our chins helped us choose mates. "Males tend to have longer chins with a square appearance and flat base. Females tend to have narrower and rounder chins," says Gargano. A 2010 study in the American Journal of Physical Anthropology argues that there would be no difference in chin shape if it weren't related to sexual attraction because there's no functional difference; males and females ostensibly eat and talk the same way. Not everyone agrees. (See #7.)  

5. WE'RE THE ONLY ANIMALS WITH CHINS. 

While humans may share some things in common with animals, chins are not one of them. "Elephants are the only other creature with a body part similar to the chin," Tawwab says. But the elephant's "chin" is actually caused by a lack of lower teeth and a big lower lip. It's not a bony protrusion, which is a real chin—and a feature that's ours alone. The human chin is considered a cladistic apomorphy, Tawwab says: a feature or body part not found in the earliest forms of a clade (group of organisms sharing a common ancestor). In short, it's evidence of our species's evolution—and one of our defining physical characteristics.

6. DOES HAVING A CHIN CLEFT IMPROVE YOUR DATING PROSPECTS? 

"Historically, numerous cultures have assigned meanings to being born with a cleft chin, usually pertaining to luckiness in love," Tawwab says. The reality is much more mundane. "The current theory suggests that a cleft chin is actually caused by an incomplete fusion of the jaw bones before birth." There are several types of clefts, as well: vertical furrows, Y-shaped furrows, and round dimples. 

7. A CHIN MAY SIMPLY BE WHERE EVOLUTION STOPPED.

A chin may not have anything to do with withstanding pressure or attracting a mate, according to Nathan Holton, an anthropologist at the University of Iowa. His research suggests that the Homo genus (including humans, Neanderthals, and other relatives) simply evolved smaller faces—and Homo sapiens most of all. The lower jaw is the last part of the face to stop growing, which causes it to be more prominent as compared to other parts of the face. The prominent chin "is a secondary consequence of faces getting smaller," Holton writes.

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The Body
10 Vital Facts About the Scrotum
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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.

The scrotum may appear to be nothing more than a bit of baggy skin, but it serves some very important functions for human health and reproduction. The testicles, which produce sperm, would be unprotected and subject to the elements without the scrotum—so without it, none of us might exist. To learn more, Mental Floss spoke to Brian Levine, a reproductive endocrinologist and fertility specialist at the New York office of the Colorado Center for Reproductive Medicine. 

1. THE SCROTUM HAS BUT ONE HUMBLE PURPOSE.

"The scrotum is a genius," Levine tells Mental Floss. While that may be a stretch, he says that the main purpose of the scrotum "is to hold the testicles outside of the body," which helps to keep the testicles cooler than body temperature. Because sperm are so sensitive to temperature fluctuations, this helps preserve their health.

2. HOT TESTICLES CAN CAUSE HEALTH AND FERTILITY PROBLEMS.

"Increased body temperature or temperature in general [such as a hot tub] leads to chromosomal abnormalities. By keeping the temperature lower you protect the DNA being formed to put the sperm together from having inborn errors," Levine explains.

3. TEMPERATURE REGULATES TESTICLE HEIGHT.

As the body gets colder, muscle fibers bring the scrotum closer to the body to regulate them. When the person is warmer, they will hang lower from the body. "The average person has one testicle higher than the other," Levine says. Size and shape variance of testicles is not in and of itself cause for concern—unless you experience a sudden change.

4. COOLER SPERM ALSO SWIM BETTER …

Also by keeping the testicles at a lower temperature, metabolically, Levine says, "you keep sperm swimming slower, so you end up preserving them."

5. … WHICH IS WHY SOME HAVE SUGGESTED EXPOSING THE SCROTUM TO OPEN FLAME OR A HOT-WATER SOAK.

A 2013 study [PDF] on birth control methods of an indigenous culture in Zimbabwe describes how men were instructed to expose their testicles to "above average heat from fire" in the belief that this would weaken the sperm. While there is a connection between temperature and sperm health, this is not a recommended practice for birth control as it is unlikely to successfully reduce the sperm count. In addition, the study notes, "testicles with too high of a body temperature are associated with testicular cancers," though others argue that the jury is still out on that purported connection. Either way, you should probably keep your scrotum away from open flame.

In a similar vein, Marthe Voegeli, a Swiss doctor and early pioneer in fertility in the 1950s, designed a study in which men sat in a shallow or testes-only bath of 116°F for 45 minutes daily for three weeks. Her study claimed that this resulted in between four and six months of infertility. Fertility returned to normal eventually, and children born of those men were healthy and normal. She took her method to India, to help families suffering from famine and poverty prevent further pregnancies. While she claimed her methods to be successful, most doctors today would not recommend this as a reliable contraceptive practice.

6. YOU CAN GET MELANOMA OF THE SCROTUM.

Even the scrotum is susceptible to cancer, Levine points out. "Wherever there's skin, you can get melanoma," he says. This can be a result of metastases of cancer that spread from somewhere else in the body, or, if you're a nude sunbather, be warned: "If you expose it to sunlight, you can get melanoma."

7. LACK OF A SCROTUM CAN MEAN THIS …

If you are male, not prepubescent, and don't have a scrotum, it may mean you have undescended testicles, Levine says, "which can end up leading to infertility." Most testicles will descend eventually, but sometimes they can be helped along by surgery.

8. BE AWARE OF THESE COMMON CONDITIONS OF THE SCROTUM.

Common issues of the scrotum that may require surgical intervention include varicoceles, which are essentially varicose veins in the scrotum that can cause infertility by pooling blood, which can effect sperm count and motility. Varicoceles can also cause testicles to fail to develop normally or shrink. A hydrocele, which doctors informally call "water on the testicle," Levine says, is simply a fluid-filled cyst that surrounds a testicle and causes swelling in the scrotum. Levine adds that since the scrotum allows for good evaluation of testicles, "If you feel any lumps, bumps or abnormalities, you should see a medical professional."

9. SURGICAL TECHNIQUES FOR THE SCROTUM AND TESTICLES HAVE COME A LONG WAY.

Should you need surgery for one of those conditions, or for a vasectomy, Levine reassures that modern day surgical techniques "mostly spare the scrotum and require a minimal, barely visible incision in the testicle." Weill Cornell Medical Center has even perfected what they call a no-scalpel vasectomy that uses specialized forceps instead.

10. WHY WERE CHIMNEY SWEEPS PRONE TO SCROTAL CANCER?

In the late 1700s and early 1800s, chimney sweeps—who were often young boys because they were small enough to fit—would develop scrotal cancer from creosote collecting between the skin folds on the scrotum.

Sir Percival Pott, an English surgeon considered the father of orthopedics and the first to draw the connection between occupations and certain illnesses, also made the connection between chimney sweeps and scrotal cancer, writing: " … there is a different disease peculiar to a certain set of people, which has not, at least to my knowledge, been publicly noticed; I mean the chimney-sweeper's cancer. It is a disease which makes its first attack on, and appearance in, the inferior part of the scrotum; where it produces a superficial, painful, ragged, ill-looking sore, with hard and rising edges: the trade call it the soot-wart." (We know now that a chemical in soot caused genetic damage to chromosome 17.)

After this connection was made, physicians recommended that chimney sweeps change their clothes weekly and wash their genitals daily.   

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