The structures which, if injured or worn out, can cause pain include: muscles, fascia (the tissue covering the muscles), ligaments, discs, bones, joints, and nerves.
When the pain is from torn muscles or fascia (the sock covering the muscles), there is usually tenderness to touch in the involved areas. When the pain is from a disc or ligament or joint problem, which are deeper structures, it is usually difficult to reproduce the pain by touching the back of the neck.
When pain is from cervical degeneration, patients can have pain in the neck, between the shoulder blades, and/or headache.
To appreciate the types of abnormalities that can be seen on xrays, look first at this cervical spine xray that would be considered normal.
The disc spaces, the cushions between the bones, are all about the same thickness in this x-ray to the right.
Note also the curve of the cervical spine: that there is a slight bow forward of the neck bones, with a curve that is concave (the hollow side) towards the back.
Now compare the x-ray above to images below and to the right showing degenerative changes:
Bone spurs are easy to see on the front of the disc space, but when they form on the back side of the disc, they can cause compression of the nervous structures including the spinal cord or the nerve roots.
Pictured on this MRI below, looking at the cervical spine from a sagittal (side) view of a different patient, the arrows indicate bulging or herniated discs that in this case are touching the spinal cord.
In this case, without the MRI, we could not have seen the herniated disc at the C3-4 level. Note that the disc height is not significantly decreased.
On the cross sectional view, the C3-4 herniated disc can be seen indenting and impinging upon the spinal cord.
Since there is not much extra room around the nerves and spinal cord, it would make sense that a small mass next to the nerves and spinal cord can cause significant symptoms.
Another example: here is a section through a segment without symptoms. There is a small disc bulge marked by an asterisk, but this bulge is not likely causing problems, as there is no pressure on the spinal cord or an exiting nerve root.
However, in this other segment on the same patient, there is a large herniation at the level pictured here. This extruded disc material almost blocks the path for the exiting nerve root on the right side, which correlated with the patient’s right arm pain and numbness.
Some other examples of cervical disc herniations.