The Anatomy of the Intervertebral Foramen

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The intervertebral foramen, also called the neural foramen, is the opening between the vertebrae through which spinal nerve roots travel and exit to other parts of the body. The word "foramen" is the singular form, while "foramina" is the plural form.

If the foramina narrow, they can put pressure on the nerve roots near them, causing pain. This is called neuroforminal stenosis.

Anatomy

The vertebrae are the building blocks of the spinal column. Their purpose is to protect and support the spinal cord and also bear the majority of the weight put upon your spine.

Structure

The large, round portion of bone that makes up each vertebra is called the body. The body of each vertebra is attached to a bony ring. When the vertebrae are stacked one on top of the other, this ring creates a hollow tube through which the spinal cord passes.

The intervertebral foramen is the opening between every two vertebrae where the nerve roots exit the spine. The nerve roots travel through the foramen to reach the rest of your body. There are two neural foramina between each pair of vertebrae—one on each side.

Function

The intervertebral foramina are essentially "exit routes" where the nerve roots exit the spine and continue to branch out to all parts of the body.

Without the foramen, nerve signals could not travel to and from the brain to the rest of your body. Without nerve signals, your body would not be able to function.

Associated Conditions

One common problem that can affect the neuroforamina is spinal stenosis. Stenosis is a general medical term that refers to narrowing. It is usually, but not always, an age-related disorder related to arthritis.

Spinal stenosis can occur in two places: The spinal canal and the foramina. When spinal stenosis occurs in the spinal canal, it's called central canal stenosis.

With pain due to neuroforaminal spinal stenosis, arthritis-related bone growth (also known as bone spurs or osteophytes) that are present in one or more foramen sort of "bump into" the nerve root that passes through that space. As they do this, they may cause pain or other symptoms down one leg or arm. This type of pain is called radicular pain if you experience pain only, or radiculopathy if the pain is accompanied by other sensations as well.

The main symptom of neuroforaminal stenosis is neurogenic claudication—a kind of cramping that is related to your posture. Most of the time, people with spinal stenosis feel better when they flex (bend forward at) the trunk, and worse when they arch their backs. Other symptoms include weakness and/or difficulty walking more than short distances.

Treatment

Treatment for stenosis is usually aimed at relieving pain and preventing nerve symptoms from occurring or getting worse. Conservative treatments are often effective enough. These include nonsteroidal anti-inflammatory drugs (NSAIDs), physical therapy, regular exercise, and cortisone injections.

Complementary treatments such as acupuncture, massage, and chiropractic may also be helpful.

Surgery is not commonly done for most cases of spinal stenosis, but your doctor may suggest it if you experience one or more of the following:

  • Radiculopathy (pain, pins and needles, electrical sensations, and/or weakness going down one arm or leg)
  • Neurogenic claudication in your low back
  • Myelopathy in your neck and/or upper or mid back (myelopathy symptoms are spinal cord related and occur in central canal stenosis.) 
  • Incapacitating pain

There are different surgical techniques used to treat spinal stenosis. One such technique is called decompression laminectomy, which entails removing the buildup of bone in the spinal canal. A spinal fusion surgery is often also performed at the same time.

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