[my neck muscles are very tense]

Those are probably spasms, spasms can be at varying levels/stages -
mildly uncomfortable, very uncomfortable & limiting, or severe (rock hard and seized up). been there , not fun at all...

A good doc, PT, DC should be able to tell by just feeling those muscles if they are in spasms.
If spasms there is usually trigger points also.. have to treat the trigger points to fully resolve the spasms.
http://neurotalk.psychcentral.com/thread125577.html