The most important role of the neck is that it supports the head and that it houses arteries that supply blood to the brain from the heart. The brain is the "computer" of the entire body so if it doesn't get much blood, it will perform under par and all the systems of the body will malfunction.
The vital part of the brain that controls our heart rate, breathing, immune system, hormones, coordination, balance, and sleep is called the "subconscious brain," which lies below the "conscious" or cortical brain. Everything in the body is automatically controlled from there.
The pair of arteries that nourish this vital part of the brain, is located in canals inside the neck vertebrae.
The neck is very fragile and it can move in all sorts of directions because of the sensory organs like the eyes, ears and nose. This is a disadvantage as the vertebrae can easily "disalign," or its joints can frequently get dislocated, due to whiplash, birth injuries, neck trauma, etc. Moreover, stress, posture, and excess computer use can stiffen the neck. The result is reduced blood supply to the brain and its subsequent malfunction. That causes poor well-being, reduction in energy level, and breakdown of the immune system, etc.
Thus the neck is very important for our health. We must look after it. The massage and exercise techniques are described in my latest book, The Neck Connection. It also explains what happens when the neck does not function properly.