Your Spinal Column

Your Spinal Column

Your spine is made up of spinal bones (vertebrae) each of which has a hole in its center. The holes all line up to form a canal where the spinal cord lies. Spinal nerves emerge from the cord and exit between the vertebrae, and travel throughout your body.

The spine consists of 24 moving segments plus the sacrum and the coccyx. The first of the seven cervical (neck) vertebrae (C1) holds the skull. The second (C2) permits most head turning and tilting. Cervical vertebrae C3 through C7 continue down through the neck. The twelve thoracic (mid-back) vertebrae (T1-T12) all connect to the ribs in back, and all but two (T11 and T12 which “float”) attach to the sternum in front. The five lumbar (low back) vertebrae are the biggest, thickest, and most massive. They support the weight of the entire spine, and that’s one reason why so many spinal problems are in the lower back area. The sacrum is a triangular shaped bone made up of five fused vertebrae. The sacrum and the hips on either side make up the pelvis. Below the sacrum is the coccyx, a small segment made up of four fused vertebral segments.

SPINAL CURVES

The cervical, thoracic and lumbar curves give your spine strength, stability, and flexibility. The neck and lumbar curves have a normal lordosis, or forward bend, and the thoracic curve has a normal kyphosis, or backward bend. In an unhealthy spine, the curves change, they can reduce, exaggerate, or even reverse! Viewed from the front, the spine appears to be more or less straight.

THE INTERVERTEBRAL DISC

The intervertebral discs are little pads that lie between the vertebrae. Each disc has a tough outer ring (annular fibrosis) and a soft gel-like center (nucleus pulposi). The discs separate the vertebra and, because they’re knitted into the bones, also join them together. They act like little shock absorbers, cushioning the bones so they don’t crash against each other as we walk which would be very painful. Discs help give the spine its curve, flexibility, and strength. The 23 discs in our spine also make up about a third of the length of the spinal column and that’s why we are about 1/2 to 1cm taller in the morning than we were the night before; the discs flatten out a little after a day of standing and then regain their volume when we sleep.

Herniation of a lumbar disc often puts pressure on the nerve roots, causing leg pain →

SPINAL NERVES

Along the length of the spinal cord, at each disc level, exit a pair of spinal nerves. Through these the brain communicates with the different areas of the body, from fingers to toes. These spinal nerve roots exit through the space created by the intervertebral disc. This explains why vertebral or disc problems often cause symptoms at locations far from the vertebra (as in low back pain with various leg symptoms, or neck problems with arm symptoms). When a spinal nerve is compressed, stretched, rubbed, or otherwise irritated, there begins a complex of symptomatology, often with pain and altered function as the end result. This process is explained in more detail in the Spinal Nerve Stress section.