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The Spinal Motorway

The spine not only acts as a skeletal structure to keep us upright, but it is also the channel connecting your brain to the rest of the body. The neural structures, or in simple words the nerves connecting the brain to the rest of the body, has to pass through this superhighway. This superhighway is like a motorway and has multiple cars (nerves) traveling towards various destinations.  As they travel along the motorway, one by one these cars leave via the exit slip roads towards various cities or body parts.  

As in the motorway, it can be divided into the main “M” road, followed by a slip road or exit road followed by A and B road. The M part is in the center and harbors all the cars or nerves in the motorway, and one by one these cars leave the motorway through the exit road


The Motorway, or the superhighway, has been demonstrated in a sequential MRI scan of the lumbar spine. The M part of the motorway is outlined in blue and cars (Nerves) are marked in yellow. As we go along the motorway from image one to three, one by one the cars move to the outer lane towards the exit road. Once the slip road appears, these cars leave the motorway towards the A and B roads (Yellow arrow).

Imagine you are driving and the exit road leads to a tunnel; this tunnel is called the foramen or keyhole. It appears like a keyhole at your door and the traveling car or nerve sits in the middle of it. Once the car travels through the tunnel, it continues the journey through the A and B roads. The A followed by B roads travel further down to the hands and feet.

Image by Mārtiņš Zemlickis

The Tunnel or Foramen outlined in blue is a Keyhole shaped passage through which the cars (Nerve -Outlined in green) passes on its way to their destination. The tunnel can collapse or get distorted due to various causes and cause entrapment of the nerve. The tunnel outlined in red is an example of spondylolisthesis related collapse and foraminal stenosis.

Obstruction or delay in any of these parts of the motorway will cause problems further down the path. It is essential to go through these findings on the MRI scan during your consultation for a better understanding of your condition and treatment options. 

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