Our body has a lot of ways to be aware of our position and the position of our limbs. We do depend on vision in many ways, but what many people find surprising is that the body has receptors all over to give information to the brain about balance!
One of the most important ways that we know where we are is by the communication of the neck muscles about their activity. So when someone has an injury that causes neck pain, it is likely that there is a lot of misalignment and imbalance in the muscles and possibly the bones in the cervical spine (aka the neck).
Interestingly, when the communication from the neck muscles is changed from an injury or other cause of damage, it can cause symptoms that are beyond simple neck pain. This type of disruption (a muscle spasm or tightness) can also cause headaches and dizziness and, of course, fatigue!