My neck and jaw are the biggest contribution to my migraine (might even be the only factor). I have a misaligned C1. When I found a NUCCA chiropractor (works only with adjusting C1 using angles - NO twisting) I had zero migraines, zero stiffness - it was amazing, I slept great, woke with tons of energy and had zero pain in my body. Then I had jaw surgery to finalize a fix to my misaligned teeth so my severe TMJ would be gone forever. The surgeon over corrected and has caused the TMJ pain to increase exponentially, and my neck would not stay in alignment since the surgery. Slowly health deteriorated to chronic severe migraines, severe daily pain, depression and most likely Fibro. And finally a severe car accident (blacked out on the highway because of a migraine - woot woot) and ended up with whiplash on top of my lax ligaments as they were.
I am working with a doc now that does nerve blocks and trigger point injections twice a week on me - head, jaw, neck and shoulders. It does help. I also have done prolotherapy (injecting sugar solution) and PRP (injecting platelets) into my jaw and neck joints to re start healing of my ligaments. My doctor is sure that having loose ligaments causes your body to tightened the muscles to help stableilize the neck - in the progress there are squeezing the nerves and causing them to fire pain when there shouldn't be.
So YES your neck can be the only cause of migraines. Hope this helps you.