Never hit a vein in my quad, i find it is best to sit in a comfortable chair, with your leg at a little more then 90 degree angle (maybe 120 or so). Flex your quad to see where the different parts of the muscle are, then stay with the outside part, somewhere in the middle. I used to do inject there with my leg almost straight out, but i would get an annoying quad twitch every couple of injects. Now I never have a problem. Lol if you really want to see ill shoot some b-12 there right now and take a pic.