Sciatic Nerve

The sciatic nerve is the longest, largest nerve in your body. Your sciatic nerve roots start in your lower back and run down the back of each leg. Sciatica is the pain or discomfort if your sciatic nerve gets compressed or pinched. People who are pregnant, have a sedentary lifestyle or have diabetes have a higher risk of sciatica.


What is the sciatic nerve?

Your sciatic nerve is a long, important nerve that starts just outside of your spine and then travels through your pelvis, into your butt and then to the back of each thigh in each leg. It's a mixed nerve, which means it has both motor (movement) and sensory (sensation) fibers. The sciatic nerve is the largest nerve in your body and is the major nerve to your leg. It allows you to walk, run and even stand.


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What is sciatica?

People regularly state or are told they have sciatica. In fact, people sometimes use the term to describe symptoms that aren't included in the actual diagnosis. In addition, many feel that if they have sciatica, there are implications about the cause and the treatment. What is important to know about sciatica is:

  • It's a common problem, almost all of us will suffer the symptoms at some point in our adult life.
  • Sciatica is defined as something that causes significant irritation of the sciatic nerve (see below) resulting in shooting nerve pain in one or both legs.
  • Sciatica is rarely caused by a serious condition such as a tumor, infection, or blood clot.
  • Many times, sciatica will resolve on its own or with medical interventions.


What is the purpose of the sciatic nerve?

Your sciatic nerve provides two types of functions:

  • Motor function: Helps the muscles in your leg and feet move.
  • Sensory function: Helps you feel sensations in your legs.

Although your sciatic nerve passes through your gluteal muscles (butt), it doesn’t provide any nerve branches to these muscles.



Where is the sciatic nerve located?

The sciatic nerve starts just outside the base of your spine (lumbar spine and sacral region). It runs through the top of your gluteus muscles (butt) and down the back of your thighs (hamstrings) and lower legs (calves).

How big is your sciatic nerve?

Where your sciatic nerve starts in your lower back is only about 1 centimeter (1/2 inch) wide. As the nerve extends down your legs, it widens slightly. At its thickest point, your sciatic nerve is about 2 centimeters (less than 1 inch) in diameter, or about the size of a penny.


What are the sciatic nerve roots?

Five different nerve roots make up your sciatic nerve:

  • Two nerve roots start in your lower back (lumbar spine).
  • Three nerve roots start at the bottom of your spine (sacrum).

These sciatic nerve roots join just outside the base of your spine to form the sciatic nerve. All the roots on the left side combine to form your left sciatic nerve while the same is true of the right side roots which combine to form the right sciatic nerve.

What are the sciatic nerve branches?

At your knees, your sciatic nerve splits into two main branches:

  • The common peroneal nerve runs from the outer part of your knee to the outer part of your foot (and it also splits into two main branches just below the knee).
  • The tibial nerve runs down the back of your calf, extending to your heel and the sole of your foot.

Your sciatic nerve also contains smaller branches at your:

  • Hip.
  • Inner thigh.
  • Lower legs.
  • Feet.

Conditions and Disorders

What conditions and disorders affect the sciatic nerve?

People often use the term sciatica to explain any pain that affects your sciatic nerve. Sciatica occurs when your sciatic nerve becomes pinched, irritated or inflamed.

Causes of sciatica can include:

  • Bone spurs (osteophytes): Hard bumps that form and grow on a bone.
  • Degenerative disk disease: When the jelly-like cushioning between your vertebrae (spinal bones) wears down.
  • Herniated disks: When one of your spinal disks bulges through its protective outer ring.
  • Piriformis syndrome: When your piriformis muscle (a gluteal muscle) compresses your sciatic nerve.
  • Lumbar spinal stenosis: A narrowing of your spinal canal in your lower back.
  • Spondylolisthesis: When one of your vertebrae slips out of place and onto the vertebra beneath it.

What are the symptoms of sciatic nerve conditions?

Sciatic nerve pain may come and go or it may be chronic (long-lasting). Sciatica can also cause:

  • Burning sensations.
  • Muscle weakness.
  • Numbness.
  • Sharp or shooting pain.
  • Tingling or “pins and needles” sensations.

Often, sciatic nerve pain worsens if you stay in one position for long periods. It may also flare up when you move forcefully and suddenly, such as when you sneeze.

What tests might I have to check the health of my sciatic nerve?

Your provider usually performs a physical exam to check the health of your sciatic nerve. Your provider may ask you to:

  • Lift each leg one at a time.
  • Squat.
  • Walk on your heels.

You may also have imaging tests to evaluate your sciatic nerve, including:

  • CT scan, using special computers and X-rays to create images of internal structures from multiple angles.
  • Electromyogram, measuring electrical impulses and muscle response.
  • MRI, creating detailed images of soft tissue with magnets and radio waves.
  • X-ray, using low-dose radiation to take pictures.


How can I keep my sciatic nerve healthy?

To reduce sciatic nerve pain and keep your sciatic nerve healthy, you can:

  • Apply heat and cold to your lower back.
  • Stretch and warm-up before exercise.
  • Take breaks to get up and stretch throughout the day, especially if you have a desk job.
  • Use topical pain relievers (gels, creams or lotions) like capsaicin (Capsagel®, Zostrix®), menthol or methyl salicylate (Bengay®) or trolamine salicylate (Aspercreme®, Myoflex®).
  • Wear a back or hip brace to stabilize your spine.

How do I know if I’m at risk for sciatic nerve problems?

Some factors can increase your risk of sciatic nerve conditions, including:

  • Age, with risk increasing between ages 30 to 50.
  • Diabetes, since it increases your risk of nerve damage and neuropathy.
  • Jobs that require heavy lifting and twisting your spine.
  • Pregnancy.
  • Running, which increases your risk for piriformis syndrome.
  • Sedentary lifestyle.
  • Smoking or using tobacco products.

A note from Cleveland Clinic

Your sciatic nerve is the largest nerve in your body, running down the back of each of your legs. Any condition that compresses or pinches your sciatic nerve may lead to sciatica. To prevent sciatica, stretch frequently, especially if you have a sedentary lifestyle. While sciatica is painful and can even be debilitating, it usually clears up with self-care

Medically Reviewed

Last reviewed on 06/15/2021.

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