1. There’s a small tendon called the Palmaris longus muscle that 15% of people just don’t have.
If you have one, it runs from your wrist into your forearm. Try flexing your wrist after putting your thumb and little finger together. If you can feel/see two tendons, you have a Palmaris longus (it will be pretty obvious).
2. Some people faint after they pee.
3. Your ovaries/testes developed in the same place as your kidneys.
Good explanation here on Quora. This is why, if you kick someone in the balls, they’ll also feel pain in their lower back. Not necessarily one to try at home though.
4. You won’t be able to move your ring finger when you put your hand on a flat surface like this.
To try it, put your fingers on a flat surface with your palm lifted up, then bend in your middle finger. Then try lifting your thumb, little finger and index finger one by one. Done? Now try your ring finger. HAHAHA. Sorry.
Your index and little fingers each have their own extensor muscles (the ones you need to be able to move them), but your middle and ring finger share one. So when you lock your middle finger underneath your hand, you can’t move your ring finger.
5. Your big toe is a toe (duh), but your thumb is not a finger.
So if you say you have eight fingers, you’re not lying.
6. Your left kidney is higher up than your right kidney.
Because your liver is muscling in on the space too.
7. You can maintain your blood sugar without eating for up to 2 or 3 days.
Normal blood sugar is equivalent to about a teaspoon dissolved in your entire volume of blood, so it’s actually a pretty small amount.
After that you enter a state called ketosis, where your liver has broken down your glycogen stores. Then you’ll start to “smell hungover” even when you’re not.
8. Adults have fewer bones than a baby.
We start out with over 300 bones, but as we grow up some fuse together and we end up with 206.
9. Humans can’t breathe and swallow at the same time.
Because of the placement of our voice boxes.
10. Your body secretes about 3 grams of IgA antibodies every day.
IgA antibodies plays a vital role in protecting your body from foreign microorganisms and can be found in your saliva, tears and mucus (and in breast milk, too).
11. There are about 7000000000000000000000000000 atoms in a human body.
That’s 7 followed by 27 zeroes and applies to a person weighing 70kg.
12. Every atom in your body is billions of years old.
You are 9.5% hydrogen, and that was made in the big bang 13.7 billion years ago. Heavier atoms, carbon (which makes up 18.5% of your body) and oxygen (65%) were forged in stars and scattered across the universe when they died.