Our Brain controls everything we do. Nerves run down from and up to the brain for us to move muscles & feel sensations. They’re bundled together in the Spinal Cord, which is housed in the Spinal Column, with a space for it called the Spinal Canal. So at every level of the spine, nerves run in & out of the Cord to and from our arms, legs, chest, abdomen, wherever. The following simple diagrams may make this easier to visualize.
The Spinal Column consists of:
- Bones — vertebrae (plural; each of them is a single vertebra)
- Disks — made of cartilage, they separate & cushion the bones so the spine can bend
- Spinal Cord — a bundle of nerves from the brain running down the neck and back
- Nerve Roots — where different nerves exit at each level, going to the arms, legs, etc.)
The picture below shows these structures. It also shows the top “Herniated Disk” has “slipped,” pressing on a Nerve Root which will cause pain and maybe weakness down part of that particular arm or leg.
Osteoarthritis, aging of the spine’s facet joints, is a common cause of neck & back pain. The facet joints are the parts of each vertebra which connect with another. They’re lined with cartilage, which can gradually wear away, causing bone to touch bone. See the picture below:
Another cause of back or neck pain is Spinal Stenosis, when the spinal canal becomes too narrow with age. A very rare cause of back or neck pain, which can cause paralysis, occurs if infection or tumor occurs in the epidural space right on top of the spinal cord (see diagram below). Viruses and other diseases can affect the spinal cord itself. See Spinal Cord Diseases.
There are also rare but serious Bone Diseases, like infections or tumors. However, the vast majority of cases of back or neck pain aren’t due to any of these unusual conditions. They’re caused by Strains of muscles or Sprains of the ligaments that lie all around the spine (not shown in pictures).