The name kind of gives this answer away. Illio-Tibial Band tells you where the tissue coming from and where it is going. What it amounts to really is dense connective tissue that attaches (via glutes and tfl)from about a third of the way down your thigh that cinnects to the tibia. Being that it runs from the illium on the hip to tibia, it is certainly a two joint muscke.
hope this helps,