Can tight neck muscles cause jaw pain and stiffness or is it the other way round?

Muscle pain: It can work both ways. When one muscle is sore, the ones around it may compensate and then become sore themselves. As a dentist i see it start in jaw and go to neck more often, but I am sure a chiropractor might see more neck stiffness lead to jaw problems.

Both are possible.: Tight neck muscles can cause pain ; lead to tensing of the jaw causing stiffness and pain. But tensing of the jaw can cause stiffness ; pain and then cause tensing of the neck muscles!

Jaw pain: In all my years of practice, I have never seen neck muscle tightness or spasms cause jaw pain. I have seen patients with tooth or jaw pain complain of radiating or referred pain to other areas of the head and neck.

Either way: It is possible that it can go either way. The muscles do interact and I have had jaw pain cause muscle pain and visa versa. I would suggest seeing a craniofacial pain specialist for an evaluation.