Facet joints are small joints located between the vertebrae in the back of your spine, and they can be a source of back pain. One way to determine whether they are the source of your pain is to perform a medial branch nerve block injection.

See Facet Joint Disorders and Back Pain

A medial branch block is typically used as part of a 2-step diagnostic and treatment approach. Watch: Medial Branch Block Video

Our video walk-through can help you visualize this relatively common procedure.

See Medial Branch Nerve Blocks

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Video highlights

In the image above, the facet joints, also called zygapophysial joints, are shown in purple. They are located behind the spine, and they add stability to your spine as it twists, flexes, and bends.

See Spinal Anatomy and Back Pain

Medial branch nerves (pictured in purple above) are located on each facet joint. Their function is to carry pain signals to your brain.

See Anatomy Of Nerve Pain

Conditions like spinal stenosis and osteoarthritis, along with an injury to your spine, may all lead to the inflammation of your facet joints. When this inflammation occurs, your medial branch nerves transmit pain signals to your brain.

See Osteoarthritis of the Spine

If your doctor thinks facet joint inflammation is the source of your pain, she or he may recommend a medial branch nerve block injection to help confirm the diagnosis.

See Medial Branch Injection Procedure

How the injection works

To begin, your doctor will have you lie down on a table. She or he will then use a local anesthetic to numb the skin and tissue around your facet joint.

See Facet Joint Injection Procedure

Using X-ray guidance called fluoroscopy (pictured above), your doctor will next steer a small needle over your medial branch nerves. Then, a small amount of contrast dye is injected to confirm the medicine covers your nerve.

Finally, your doctor will carefully inject a numbing medicine (called an anesthetic) onto each targeted nerve. Typically, two of your adjacent nerves will be targeted at the same time.

If you experience immediate and significant pain relief following the injection, it can be assumed that the source of your pain is the facet joint.

See Facet Joint Injection Pain Relief Results

Risks and complications

Like all invasive medical procedures, there are risks associated with a medial branch block. For example, you may experience any of the following:

  • Allergic reactions
  • Worsening of symptoms
  • Discomfort
  • Nerve damage

See Risks and Complications of Medial Branch Blocks

Thankfully, these types of complications are rare, and there are minimal risks associated with a medial branch nerve block.

Learn more:

Cervical, Thoracic, and Lumbosacral Medial Branch Nerves

Medial Branch Block Results