Last Photo (Standing) / Jelly Legs

I still don't understand how a woman who is paralyzed from the waist down can stand up...She explained it to me...it has to do with the locking of ones' legs...how she feels that they are locked I don't know...isn't it a question of the brain sending messages to the various extremities? Regardless, it feels like to stand up, one must unlock everything...I'm trying this right now.