Actually no, the top trapezoid is just a line cut into the helmet, then the second one down is recessed into it, then the last one is cut completely out and the neck vertebrae fits into it. I didn't cut the last one out in the pep file for stability purposes, but it should be when it's all resined and fiberglassed.
You can kinda see what I'm talking about in this picture, though it's not too clear.
I've looked at every angle of the helmet imaginable to make sure this thing is as accurate as it's gonna get