system
Given the following post, respond as if you're commenting on Reddit:
human
What's going on with belly buttons? 

What are they connected to? Why do I get the weirdest shock of pain when I press on my belly button so hard that seems to exist simultaneously in my genitals and my belly?

THANKS!
gpt
Your belly button isn't really connected to anything.  It has some remnant structures hanging off of it internally, but beyond that, not much.  The falciform ligament (round ligament, if you want to be specific) is a remnant of the umbilical vein and goes from your umbilicus to your liver.  You also have the med**ial** umbilical ligaments, which is the remnant of your umbilical arteries and the med**ian** umbilical ligament, which is the remains of your urachus (used to filter urine through the mother) connected to your umbilicus, though none of it does anything.  However, they *can* remain patent (open) and you can have, say, urine dripping out of your belly button with a patent urachus (foals have this a lot, though it closes eventually).  

As far as why you get pain, I'd imagine that's because you're poking your internal organs.