Coming back down
After your brain and face use the oxygen in their blood, that blood has to get back to the heart. It travels down your neck through the jugular veins (JUG-yuh-ler).
Going down is easy when you stand or sit up, because gravity helps pull the blood down.
The jugular veins join with veins from your arms, and they all flow into the top big vein, the superior vena cava, and then into your heart.
Deep veins and outer veins
On each side of your neck there is a deep jugular vein and an outer one. The deep one carries most of the blood from your brain. It runs right next to the carotid artery, tucked safely inside.
The outer one runs closer to the skin. It brings blood from your face and scalp.
Sometimes when a grown-up sings a long, loud note or blows up a balloon, you can see the outer vein puff up on the side of their neck. It goes back down when they relax.
Upside down
If you hang upside down from the monkey bars, your face can turn red and feel full. That is because gravity is now pulling blood toward your head instead of away from it.
Flip back up, and the jugular veins drain the extra blood back down to your heart. The red goes away in a moment.
Jugular comes from an old Latin word for the throat, the front of your neck.