I have no clue if it does. :(  I found it by going into the setup room one day. It's called a Neck Dummy or at least, it was on the rig I used. Mind you, I didn't see it for the longest time until one day, I went into the setup room and there it was...really tiny like.  I had to delete it and once I did, whamo...no broken neck.  Sad thing is that I ended up having to redo the whole rig anyway because of the hands, which were geometry swaps on that old rig.  Ah well, live and learn. Anyway, zoom in as close as you can to the neck and chest area, that's where I found it and it may be on your rig too.