by Vonda J. Sines

Created on: December 21, 2009

You might not recognize it as a spinal problem at first. Spinal stenosis can occur in your upper or lower back but can cause cramping, pain or numbness elsewhere. The most common sites beyond the back are your neck, legs, shoulders and arms.

This condition can also cause symtoms like a loss of sensation in your extremities and, in some patients, can interfere with bladder or bowel function, according to the

Mayo Clinic.

In order to understand what causes this condition and how it develops, a basic understanding of the anatomy of the human spine is helpful.

Parts of the Spine

Vertebrae. Your spine has 24 of them stacked on top of each other. It also had a sacrum and a tailbone. Adults usually have seven neck - or cervical - vertebra. Twelve vertebrae are located at the back wall of your chest and are called thoracic vertebrae. The lumbar vertebrae are found at the inward curve of your lower back. Five fused vertebrae between the hip bones form the sacrum. Your tailbone is actually three to five fused bones located at the tip of your spine.

Ligaments. They're tough bands of elastic tissue whose mission is to keep your vertebrae in place whenever you move.

Intervertebral disks. They separate your vertebrae and consist of elastic pads of cartilage. As a result, your spine is flexible. These disks function like shock absorbers for your vertebrae during motion. Each one has a center like jelly surrounded by a ring of fibrous tissue.

Facet joints. They're found on the sides as well as the top and bottom of the vertebrae. They connect one vertebra to another and stabilize your spine while still keeping it somewhat flexible. These joints slide smoothly because they're coated with a lubricant.

Spinal canal. It's a channel through which the spinal cord passes in your spine. Various degenerative changes can make it too narrow for comfort.

Spinal cord. It's actually a long bundle of nerves stretching from the brainstem at the bottom of your skull to your second lumbar vertebra, which is located in your lower back. Where the cord ends, another set of nerves called the cauda equine heads down the spinal canal. The nerves inside your spinal cord carry impulses between your brain and the rest of your body. There are 31 pairs of spinal nerves in your back and neck.

How stenosis develops

Doctors recognize two types of stenosis. Primary spinal stenosis is already present at birth. Most people have the other kind, acquired spinal stenosis, which sets in during the aging process.

The primary

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