system
Given the following post, respond as if you're commenting on Reddit:
human
What is actually going on when you have a "crick" in your neck?

What is happening physiologically that causes that feeling of stiffness/soreness in one's neck?
gpt
Some of the muscles around the neck or shoulder area have become tight and shortened so that there is no longer enough space in the neck for the vertebrae to turn freely. There are endless different factors that can cause the muscles to shorten.