How Your Spine Works

The "Tunnel" Inside Your Vertebrae — The Spinal Canal

What Is the Spinal Canal?

Each vertebra has a hole in its center.

When the vertebrae are stacked together, these holes line up to form a continuous tunnel running down the length of your spine.

This tunnel is called the spinal canal.

Cross-sectional view of a lumbar vertebra showing the intervertebral disc, spinal canal, facet joints, and ligamentum flavum

Think of it this way: The spinal canal is like a garden hose about 2–3 centimeters (roughly 1 inch) in diameter. Your precious nerves travel inside this hose.