Your total health and happiness depends upon the health of your neck. Without a healthy neck your journey through life will be much more difficult.
Your skull is perched on top of the Atlas Vertebrae and the brain stem extends into this portion of the spinal column. It is also contains the attachment points for the upper cervical spine to the skull.
When in the proper posture, the skull is nearly balanced and needs very little effort by the big muscles to remain looking toward the horizon.