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The Ultimate Back Pain Relief Tips Blog

What's Sciatica?

Posted by Dr. Jeff Winternheimer D.C. on Thu, Sep 06, 2012 @ 10:13 AM

sciatica diagram, sciatica picturesWhen I wrote the article, "What Causes Sciatica? The Five Most Common Causes," I made the assumption that people knew what sciatica was.  I received many emails that said “What's Sciatica?”  So the goal of this blog is to better explain what sciatica is. 

What is Sciatica?

It’s important to start by explaining that the name sciatica is the name of the symptom.  This is vital because people often think that the name also implies the cause. But this is not the case the causes can be multiple (see my two part blog on the 5 causes of sciatica The Five Most Common Causes for Sciatica)

The term sciatica comes from the sciatic nerve. When the sciatic nerve is pinched you have sciatica. The sciatic nerve is the nerve that supplies the lower extremities (legs). It is the largest nerve in the body; it’s about the thickness of your thumb. Because of its size when it’s pinched it can cause “severe pain!” 

  • The sciatic nerve is large because it is actually the combination of 5 different nerve roots.

A brief description of the spine is necessary to understand what the 5 nerve roots are and what they do. Understanding of the nerves starts at the top, the brain. The brain is the information processing center; it sits on the top of the spine and is protected by the skull.  The bottom of the brain is the brainstem; this is where the brain transitions into the spinal cord as it enters the spine. 

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The spine is made of 24 vertebrae and each vertebra is separated by a disc, between each vertebra a nerve roots exits off the spinal cord through the vertebrae. These nerves are the communication pathways of the body. The nerves in the neck go into the arms and nerves in the low back go into the legs.

  • The nerve roots that exit the lowest part of the spine form the sciatic nerve they are; L4, L5, S1, S, and S3.
  • The 5 nerve roots join together after they exit the spine and form the sciatic nerve.
  • When any of the 5 nerve roots are pinched the result is sciatica. 

Symptoms associated with sciatica!

Because the sciatic nerve is made of 5 different nerve roots, any one of the nerve roots can be pinched and cause sciatica. So you can see that sciatica is the what, not the why. The why comes from the symptoms associated with the 5 nerve roots? And each nerve root is associated with a different type of symptom. 

The sciatic nerve starts in the low back and travels down the entire leg into the feet and big toe. The most common symptom that results from sciatica is pain that radiates down the leg.

In the next post I will address what the symptoms of sciatica are!

Sciatica Resource Center

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