The vertebrae are the bones that form your spine. The vertebrae are made to stack on top of each other in order to provide a support structure that has the ability to move. The vertebrae also protect the spinal cord as it moves from the brain down the spine. Their bony prominences which are in the back protect the nerve tissue of the spinal cord. There are also bony prominences in the front that make the spine capable of being weight bearing. The discs are the cushions between each vertebrae to protect the spine from the impact of any movements you make.
When you age, the discs in your spine, including those at C5 and C6 (bones 5 and 6 in the cervical or neck area of the spine), can lose water and dry out. When this happens the pressure of the vertebrae press harder on the disc and the disc compresses. Then the outer ring of the disc can break down, causing the nucleus or the inside area of the disc to actually bulge out.
Degenerative diseases are another reason that you might get a bulging disc at C5 and C6. These are diseases where the discs break down and begin losing their structure. This can be very painful, and in the case of a bulging disc at C5 and C6 cause a lot of pain in the neck and arms; it can even cause chest pain.
Strain on the Back
Bending, stooping, heavy lifting and even something that seems innocuous such as being on your feet for long periods can cause bulging discs at C5 and C6. This is because all of these actions can put enough strain on your back to cause this condition.
Height and Weight
Apparently those who are taller have more of a chance of developing bulging discs at C5 and C6, as well as at other areas of the spine. Having extra height or weight puts pressure on your spine and makes you more likely to have trouble with bulging discs. However, if you do exercises that develop core strength and spinal flexibility, then these things can help to reduce the likelihood of your suffering from bulging discs at C5 and C6 and elsewhere on the spine.