Medical Spine and Sports Injury and Rehab Centers Explains the Normal Cervical Spine

The normal cervical spine has a slight forward concave curve to it. Its vertebrae (bones) are specially shaped for their job of holding the head. The spinous processes of the cervical spine are longest of the spine. The intervertebral discs cushion the stress the bones experience in everyday life. The spinal canal is the smallest of the spinal column and contains the most structures of any area in the spine -- the spinal cord, the vertebral artery and spinal nerves.

The normal cervical spine is an average 14mm wide at the C5 vertebral level.

• minus 7mm -- The spinal cord at vertebral level C5 is 7mm.
• minus 3mm -- The soft tissues (ligaments, dura, veins) occupy 3mm. 
• equals only 4mm of open space -- That leaves only 4mm of space in the canal, so a disc herniation or other abnormality affecting the canal may well cause pain. (1)