Does Cracking Your Knuckles Really Give You Arthritis?

Jaysin Trevino, Flickr // CC BY 2.0
Jaysin Trevino, Flickr // CC BY 2.0

You’ve heard it before. You’re in a quiet room in among a gathering of people, and then—POP!—a little cracking noise rings out, followed by another, and another, and another. For some, cracking knuckles is a habit, while for others that little pop brings relief. And it's not just reserved for tough guys before they beat people up: Between 25 and 54 percent of all people crack their knuckles multiple times a day. But is the old wives’ tale true? Are these knuckle-crackers more likely to hurt their hands and gradually develop arthritis as they get older? 

In short, nope! Despite the rumor that kids constantly hear, it turns out there is no scientific correlation between cracking your knuckles and developing arthritis in your joints, which is when one or more of the points where your bones meet develop inflammation. 

When you crack your knuckles, you're actually doing more bursting than cracking. The popping noise you hear is caused by small bubbles bursting in your synovial fluid, a yolk-like substance that lubricates the areas between bones and reduces friction for ease of movement.

Here's how it works: When you make the motion to crack your knuckles—either by stretching your fingers or bending them backwards—you expand the joint. This causes the pressure between the joint  to decrease, as well as the ligaments that connect the bones and the joint capsule that holds all of it together. That depressurization causes gasses like carbon dioxide, nitrogen, and oxygen that are dissolved in the synovial fluid to form into little bubbles that rush into the empty space. As the joints settle back into place, the fluid also returns to its rightful place and pops those little bubbles, causing that recognizable cracking sound. 

The sensation of cracking your fingers feels good because the stretching of the joint also stimulates nerve endings found along the fingers; joints can’t be cracked more than once within 15 minutes to a half hour, which is about how long it takes for those gasses to dissolve back into your synovial fluid.

Among the scientific studies conducted to prove that there is no correlation between cracking your knuckles and osteoarthritis, one published in the Journal of the American Board of Family Medicine in 2010 found that, among a group of 215 participants between the ages of 50 and 89, arthritis was prevalent in about 18 percent of the people who crack their knuckles and in 21.5 percent who don't, making any correlation inconclusive. Probably the most entertaining study on the subject is by a Dr. Donald Unger who, inspired by his mother’s warnings as a child about getting arthritis by constantly cracking his knuckles, spent more than 60 years cracking only the knuckles on his left hand at least twice a day (in this case, the right hand served as his control). His finding, published in 1998 in a journal called Arthritis & Rheumatism, found there was no discernible sign of arthritis in his left hand as opposed to his right.

So don’t listen to what mom says, everybody—feel free to crack away!

Why Are So Many Ancient Statues Missing Their Noses?

Aninka/iStock via Getty Images
Aninka/iStock via Getty Images

Spencer Alexander McDaniel:

This is a question that a lot of people have asked. If you have ever visited a museum, you have probably seen ancient sculptures such as the one below—a Greek marble head of the poet Sappho currently held in the Glyptothek in Munich, with a missing nose:

A smashed or missing nose is a common feature on ancient sculptures from all cultures and all time periods of ancient history. It is by no means a feature that is confined to sculptures of any particular culture or era. Even the nose on the Great Sphinx, which stands on the Giza Plateau in Egypt alongside the great pyramids, is famously missing:

Full profile of Great Sphinx including pyramids of Menkaure and Khafre in the background on a clear sunny, blue sky day in Giza, Cairo, Egypt with no people
pius99/iStock via Getty Images

If you have seen one of these sculptures, you have probably wondered: “What happened to the nose?” Some people seem to have a false impression that the noses on the majority of these sculptures were deliberately removed by someone.

It is true that a few ancient sculptures were indeed deliberately defaced by people at various times for different reasons. For instance, there is a first-century AD Greek marble head of the goddess Aphrodite that was discovered in the Athenian Agora. You can tell that this particular marble head was at some point deliberately vandalized by Christians because they chiseled a cross into the goddess’s forehead.

This marble head, however, is an exceptional case that is not representative of the majority of ancient sculptures that are missing noses. For the vast majority of ancient sculptures that are missing noses, the reason for the missing nose has nothing to do with people at all. Instead, the reason for the missing nose simply has to do with the natural wear that the sculpture has suffered over time.

The fact is, ancient sculptures are thousands of years old and they have all undergone considerable natural wear over time. The statues we see in museums today are almost always beaten, battered, and damaged by time and exposure to the elements. Parts of sculptures that stick out, such as noses, arms, heads, and other appendages are almost always the first parts to break off. Other parts that are more securely attached, such as legs and torsos, are generally more likely to remain intact.

You are probably familiar with the ancient Greek statue shown below. It was found on the Greek island of Melos and was originally sculpted by Alexandros of Antioch in around the late second century BC. It is known as the Aphrodite of Melos or, more commonly, Venus de Milo. It famously has no arms:

Venus de Milo is an ancient Greek statue and one of the most famous works of ancient Greek sculpture
winduptu/iStock via Getty Images

Once upon a time, the Aphrodite of Melos did, in fact, have arms, but they broke off at some point, as arms, noses, and legs often tend to do. The exact same thing has happened to many other sculptures’ noses. Because the noses stick out, they tend to break off easily.

Greek sculptures as we see them today are merely worn-out husks of their former glory. They were originally brightly painted, but most of the original pigments faded or flaked off long ago, leaving the bare, white marble exposed. Some exceptionally well-preserved sculptures do still retain traces of their original coloration, though. For example:

Lady with blue and gilt garment, fan and sun hat, from Tanagra 325-300 BC
Capillon, Public Domain, Wikimedia Commons

Even for the sculptures that do not retain visible color to the naked eye, archaeologists can detect traces of pigment under an ultraviolet light using special techniques. There are also dozens of references to painted sculptures in ancient Greek literature, such as in Euripides's Helen, in which Helen laments (in translation, of course):

“My life and fortunes are a monstrosity,
Partly because of Hera, partly because of my beauty.
If only I could shed my beauty and assume an uglier aspect
The way you would wipe color off a statue.”

This post originally appeared on Quora. Click here to view.

Why Do People Get Ice Cream Headaches?

CharlieAJA, istock/getty images plus
CharlieAJA, istock/getty images plus

Reader Susann writes in to ask, "What exactly is the cause of brain freeze?"

You may know an ice cream headache by one of its other names: brain freeze, a cold-stimulus headache, or sphenopalatine ganglioneuralgia ("nerve pain of the sphenopalatine ganglion"). But no matter what you call it, it hurts like hell.

Brain freeze is brought on by the speedy consumption of cold beverages or food. According to Dr. Joseph Hulihan—a principal at Paradigm Neuroscience and former associate professor in the Department of Neurology at the Temple University Health Sciences Center, ice cream is a very common cause of head pain, with about one third of a randomly selected population succumbing to ice cream headaches.

What Causes That Pain?

As far back as the late 1960s, researchers pinned the blame on the same vascular mechanisms—rapid constriction and dilation of blood vessels—that were responsible for the aura and pulsatile pain phases of migraine headaches. When something cold like ice cream touches the roof of your mouth, there is a rapid cooling of the blood vessels there, causing them to constrict. When the blood vessels warm up again, they experience rebound dilation. The dilation is sensed by pain receptors and pain signals are sent to the brain via the trigeminal nerve. This nerve (also called the fifth cranial nerve, the fifth nerve, or just V) is responsible for sensation in the face, so when the pain signals are received, the brain often interprets them as coming from the forehead and we perceive a headache.

With brain freeze, we're perceiving pain in an area of the body that's at a distance from the site of the actual injury or reception of painful stimulus. This is a quirk of the body known as referred pain, and it's the reason people often feel pain in their neck, shoulders, and/or back instead of their chest during a heart attack.

To prevent brain freeze, try the following:

• Slow down. Eating or drinking cold food slowly allows one's mouth to get used to the temperature.

• Hold cold food or drink in the front part of your mouth and allow it to warm up before swallowing.

• Head north. Brain freeze requires a warm ambient temperature to occur, so it's almost impossible for it to happen if you're already cold.

This story has been updated for 2019.

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