11 Body Parts You Never Knew You Had
Think you know your body inside and out? Think again.
Eyelid holeTatiana Ayazo / Rd.com
If you tug your upper or lower eyelid away from your eye, you’ll see a tiny hole in the inner corner called the lacrimal punctum. It’s easiest to spot on your lower eyelid, but both help drain your tears. Don’t miss these other strange body parts and their surprising purposes.
The sometimes-missing arm muscleTatiana Ayazo / Rd.com
About 86 percent of humans have a palmaris longus muscle running from the elbow to the palm. To test if you have it, touch your pinky to your thumb and tighten your wrist muscles. The muscle will pop out in the center of your wrist, right under your palm. In humans, it helps wrist flexibility, but there’s no consequence if you’re born without one or if a surgeon removes it. Scientists think the muscle is probably used to help primates grip and swing through trees.
Glow-in-the-dark skinTatiana Ayazo / Rd.com
Japanese scientists used ultra-sensitive cameras to discover humans actually give off light, sort of like a firefly. You glow the most from your forehead, cheeks, and neck. The glow is the faintest when it’s late at night and at its brightest in late afternoon. Even then, though, the “bioluminescence” is one thousand times too faint for the human eye to see.
“Walking” proteinsTatiana Ayazo / Rd.com
The “motor” molecule called kinesin transports organelles and neurotransmitters within a cell. That doesn’t sound too exciting until you find out how they move. Two structures at its base, often called “feet,” make their way along a microscopic catwalk. It looks eerily similar to the appearance of a human walking, except each step is timed more like a limp and only travels eight nanometers (about three ten-millionths of an inch). Check out these other 13 strange facts about the human body.
Ear musclesTatiana Ayazo / Rd.com
Your three auricular muscles are associated with your outer ear. They would have helped evolutionary ancestors pivot their ears like a cat does, but they don’t serve much purpose to modern humans—other than a party trick. Only about 10 to 20 percent of people are able to engage those muscles to wiggle their ears. Don’t miss these 17 science “facts” that are actually false.
Goose bump musclesTatiana Ayazo / Rd.com
Ever wonder why you get goose bumps? You have tiny muscles around the hair follicles, which contract when you’re scared. The function would make other animals’ fur stand up, but because human body hair isn’t thick, you can still see the bumps.
MesenteryTatiana Ayazo / Rd.com
Scientists are still discovering new parts of the human body. As recently as November 2016, researchers officially added another organ to anatomy textbooks. Scientists used to think the mesentery—a double fold of abdominal cavity in the digestive system—was a few separate structures but now realize it’s one single organ. The organ connects the intestine to the abdomen, though scientists still aren’t sure what its function is. Find out what the 13 most promising scientific discoveries of 2017 were (including the eighth continent scientists discovered).
A tailTatiana Ayazo / Rd.com
You don’t have one anymore, but human embryos have a tail until about ten weeks into development. At that point, the vertebrates fuse into a single tailbone, which adults have inside the body. In extremely rare cases, babies are born with a tail-like bulge, but it can be removed easily with surgery. Learn the only two body parts that never stop growing.
Brain vessels connected to the immune systemTatiana Ayazo / Rd.com
In 2015, researchers discovered vessels in the brain that connect directly to the immune system. The finding could lead to new advancements in Alzheimer’s, multiple sclerosis, and other neurological diseases that deal with the immune system. Don’t miss these other 30 mind-blowing facts about your brain.
Jacobson’s organTatiana Ayazo / Rd.com
The vomeronasal, or Jacobson’s, organ helps some animals sense pheromones, which are chemicals that trigger a response in the same species. Scientists are still debating whether or not humans have one. Embryos seem to have the organ in the womb, but it disappears as they develop. Instead, adults have a pit on one or both sides of the nasal passage that doesn’t have any sensory neurons connecting it to the brain. Find out which surprising body parts are as unique as your fingerprint.