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Understanding Anatomy:


The spine, much like any other part of the body’s skeleton, has joints – in the spine, these joints are called facets. Also known as zygapophyseal joints[1], facets run the length of the spine and are what we feel popping when one “cracks” their neck or back.
Facet joints help the spine to bend, twist, and extend in different directions. Although these joints enable movement, they also restrict excessive movement such as hyperextension and hyperflexion (i.e. whiplash).
Facet joints are located in the spinal column, on the posterior portion of the vertebral bodies. The facets themselves are the product of where 2 vertebrae come into contact. At each level of vertebral level, there are 2 points of contact between each vertebral body and as a result, each vertebral level has two sets of facet joints. The facet is named based up which vertebra make up the facet. For example, the left-sided contact between the 4th and 5th lumbar vertebrae is terms the Left L4/5 facet joint.
The upper vertebra forms the top portion of the facet known as the inferior articular process (IAP). The lower vertebra forms the bottom portion of the facet – this portion is known as the superior articular process (SAP). With the SAP facing upward into the IAP, they work together like a hinge.
Facets are synovial joints. Like other synovial joints in the body, they are surrounded by a capsule of connective tissue and produces synovial fluid to nourish and lubricate the joint. The surfaces of the joint are coated with cartilage as well as loose ligaments that help each joint to move (articulate) smoothly.
CMBBEach facet joint is innervated by two small nerves (dually innervated) – paired medial branches of the posterior ramus (dorsal primary rami) of the spinal nerves.[2],[3]   The facet receives a medial branch from the spinal nerve above the facet and the nerve below. For example, the medial branches of the C4 and C5 spinal nerves innervate the C4/5 facet. The medial branch nerves control sensation to the facet joint.  When there is degeneration or inflammation within a facet joint, pain activates the medial branch nerve.  These nerves do not control sensations or muscles in your arms or legs.

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Lumbar Medial Branch Blocks
Back pain can come from a variety of sources – herniated discs, fractures, and arthritic facet joints. Even as advanced as MRI imaging is, there is no definitive way to tell exactly what is causing the pain by looking at the pictures. Lumbar Medial Branch Blocks, on the other hand, can tell your doctor not only what the cause is, but where.

Radiofrequency Ablation RFARadiofrequency Ablation (RFA)
RFA is a procedure that can be used to treat several different kinds of chronic pain throughout the body, though it is most commonly used on the neck and back. In RFA, the doctor uses fluoroscopically guided needle to target the painful nerve, or pain generator. The nerve is then bombarded with radio waves, which effectively stuns it and ceases the pain. Using RFA, the physician can treat pain without a single incision; patients have reported the cessation of pain symptoms to last a year or more.

Superior Articular Process (SAP)· Face upward
· Form the bottom portion of the facet joint and is located on the lower vertebra (i.e. the SAP of the L4/5 facet is located on the L5 vertebral body
Inferior Articular Process (IAP)· Face downward
· Form the top portion of the facet and is located on the upper vertebra (i.e. IAP of the L4/5 facet is located on the L4 vertebra
Synovial Joint· Surrounded by a capsule
· The surfaces are lined with cartilage
· The joints are filled with synovial fluid to lubricate it
Medial Branch· Innervates the facet and provides sensation of pain when irritated
· A small branch of the posterior ramus (dorsal rami) of the spinal nerve
· Each facet dually innervated as it gets innervation of the medial branch above and below

Facets are oriented differently depending on which portion of the spine they are located – this is important to keep in mind when planning interventions to treat facet-related pain.

Treatment for pain, epidural, nerve block, sciatica, pudendal neuralgia, pain with sitting

Cervical Spine – facets in the neck (cervical region) are oriented horizontally

Thoracic Spine – facets in the mid back (thoracic region) are oriented more vertically, in a frontal (coronal) plane

Lumbar Spine – facet in the low back (lumbar region) are also oriented vertically, however in a sagittal plane

Treatment for pain, epidural, nerve block, sciatica, pudendal neuralgia, pain with sitting

Cervical Spine – facets in the neck (cervical region) are oriented horizontally
Thoracic Spine – facets in the mid back (thoracic region) are oriented more vertically, in a frontal (coronal) plane
Lumbar Spine – facet in the low back (lumbar region) are also oriented vertically, however in a sagittal plane

Like any other joint in the body, facets are susceptible to sprains and degradation over time. Painful or arthritic facets are termed spondylosis or facet arthopathy. Other such pathologies often seen in facets are hypertrophic osteophytic overgrowth, subchondral sclerosis, bone marrow edema, joint space narrowing/widening, joint effusions, and periarticular soft tissue edema.[4]
The joint space can narrow or, if instability and abnormal motion occur, widen. A small amount of synovial fluid exists in the joint space but effusions are commonly seen, particularly in widened facet joints. As mentioned above, facet joints can develop arthritis, like any other joint in the body such as knee, or hip. Any of these changes can result in pain that may require treatment.
Arthritic facets (spondylosis) and spinal instability are also thought to lead to facet cysts – protrusion of articular tissue.[5],[6]  Facet cysts are fluid-filled, rounded structures with a smooth border that originate from the facet joint itself. These cysts can be painful unto themselves by causing pain within the facet or by putting pressure on adjacent nerves.

Get Answers to Your Questions at the Ainsworth Institute
The key to finding the proper treatment for any type of pain is getting a proper diagnosis.  Not all types of pain respond to the same treatments and the window for improvement can be limited. The experts at Ainsworth Institute offer the most advanced pain management treatments available today, including advanced clinical trials that aren’t yet available to the general public. Call us today for an appointment so we can get you started on your road to recovery.


[1] Osborn A: Normal anatomy and congenital anomalies of the spine and spinal cord. Diagnostic neuroradiology. 1994 Mosby St Louis 783-819.
[2] Ashton IK, Ashton BA, Gibson SJ, et al. Morphological basis for back pain. The demonstration of nerve fibers and neuropeptides in the lumbar facet joint capsule but not in the ligamentum flavum. J Orthop Res. 1992; 10:72-78.
[3] Hogan QH, Abram SE. Diagnostic and prognostic neural blockade. Neural blockade in clinical anesthesia and management of pain. ed 3 1998 Lippincott-Raven Philadelphia 837-877.
[4] Resnick D. Degenerative diseases of the vertebral column. Radiology. 1985; 156:3-14.
[5] Fujiwara A, Tamai K, An HS, et al. The relationship between disc degeneration, facet joint osteoarthritis and stability of the degenerative lumbar spine. J Spinal Disord. 2000; 13:444-450.
[6] Fujiwara A, Lim T, An HS, et al. The effect of disc degeneration and facet joint osteoarthritis on the segmental flexibility of the lumbar spine. Spine. 2000; 25:3036-3044.