Radiology.can stress loading mri of spine show up how the c-t-l spine really work under normal movement and affect head brain and movement?

Yes: Any imaging study that takes pictures in functional positions will give you much greater information than a simple study done with the affected extremity at rest.

Possibly: Weight bearing MRI can give a glimpse into what happens with loading stresses however these are typically more uncomfortable for the patient and sometimes insurance companies do not pay for this added service. Often times, using flexion/extension based spine x-rays can augment the static image of the MRI and provide more info as well.