iirc if you go higher up the exterior of the leg, you should be able to find one - there's a room with a tentacle monster and some strong red lighting in it, and I think there's a hibernation chamber connected to it. Will upload a map picture later when I'm on my PS4, if you haven't found it by then.
I think I know where you mean. The chameleons tend hang out up there so I'll have to be brave!