Ribbon spine question (Maya)

Hi, I learned how to do the ribbon spine setup from Aaron Holly’s DVD and was wondering what the purpose was of 2 of the joints used in the setup? I attached a picture with the 2 joints I’m talking about highlighted in red. They’re not used for skinning and I made a ribbon spine setup without them as a test and it seemed to work just fine. Thanks.

they’re really just for visual aid, same as when you create joints for a rig, fingertips, toeTips etc, you dont skin them.

Ah ok, thanks. Thought they might be there to help keep the joint oriented in the proper direction or something.