Back pain is one "condition" ( in fact if you have pain in each major segment of the spine it should be listed seperately imho)
Sciatica is another "condition"
Arm pain resultant from spine condition is a seperate rateable condition etc etc etc
radiculopathy is a symptom with either, but can and should be rated separately
Now what all this means is absolutely nothing, When you get your C/P exam packets you will have to describe everything, add attachement etc. LIST each diagnosis, condition, symptom etc. you have and how they affect you. Keep in mind all of your spinal issues lumbago/cervicalgia/thoratic spine whatever ARE ALL BASED ON RANGE OF MOTION TESTS AND OBSERVATIONS. If you only bend to 20 degrees for the rom, but then bend over to put on your shoes that gets noted. ( EVEN IF IT HURTS TO DO IT, AS LONG AS YOU DO IT, IT COUNTS AGAINST YOU) do not exceed the threshold at which pain begins period end of story.
Once your C/P exams are done, your PCM or random doctor will type up your NARSUM, this is where its very important to review everything, if the C/P doctor listed your conditions separately, then make sure the NARSUM lists them separately. if it does not request an IMR for any condition that you believe fails retention standards. you may not win them all, but you short yourself if you do not try.
I have 24+ conditions claimed, of which the doctor only referred me for the fake hip, I had to go back and fight to have my back, sciatica, left hip, and neck added. The review doctor only added my left hip and back (but by default that will add my sciatica), and chose to not add my neck. If I do not get a just rating from the DoD side because of this, I will go to formal and request my neck and my thigh (which I forgot to even mention in my IMR, but thats my fault). to be added as unfitting conditions.
Never stop fighting for what you perceive is just and an accurate representation of your disability, be it retirement, seperation with severance or retention, the ball is in your court very little on this ride, but when it is, you better do everything you can to control it and win.