From dull tension headaches to crippling migraines, sometimes your cranium can feel crippled. But what causes all those headaches?

You might not know that the brain itself can't actually feel pain. Instead, headaches are usually the result of muscle tension or blood flow in the head—and this video explains how and why those both happen. It goes without saying, though: if you have serious headaches, stop watching this and go see a doctor. [Head Squeeze]