ya well there are 2 different schools of thought
the 12 come from the crystal / energy workers from what I remember and not all of these exist within the body, there's one 6 inches below the feet and another one is the core of the earth, linking us with the planet, this actually makes a lot of sense to me
the secondary chakra's a valid point too as we have energy vortexes all over our body especially hands and feet and at our glands, this is where energy goes in and out of the body..
reflexology states that the end points of the meridians are at the hands and feet and the meridians are the lines at which the energy travels in the body
so it makes sense that there would be minor chakras here..
most of the major chakras correspond to glands in the body however..