I have high blood pressure, so I have to check it often. My doctor sent me home with a monitor that I can use by myself, and she told me to place it a few centimeters above the bend in my elbow.
I didn't know why until reading this article. I've seen the brachial artery in the bulging biceps of body builders, but I've never noticed it on myself.
It makes sense that this is where I'd need to take a blood pressure reading. It's a big vein with lots of blood in it.