What is Sciatica?

December 3, 2019

Author: Dr David Brown DC - Clinic Director & Chiropractor , ProBack Clinics Surbiton

• Do you have pins and needles, pain or a weakness in the back and leg?    •    Is it painful to stand from a seated position, or to simply go for a walk?   •    Or maybe these areas feel weak, like they might spasm or give at any moment?

If you answered yes to any of these, then you could have a condition called Sciatica!


One study published in the British Journal of Anaesthesia found that between 13% and 40% of our population will experience sciatica at some point in their lives. Yes, it’s that common. We’ve seen patients flushed with tears as this condition angrily flares and incapacitates. A slow pain-filled walk, a back tentatively held, and a face etched with agony can result.

What is the sciatic nerve?

The sciatic nerve is the longest nerve in the body. Several nerve roots exit from the lower spine and combine to form this single nerve. The combination increases its size and effect like small tributaries that merge to form a great flowing river. Instead of water, though, this nerve enables the flow of information.

We have a sciatic nerve on each side of our body. It powers the muscles at the back of the thigh, and the nerves that come from it innervate the calf and other lower leg muscles. This is how we can push off, flex and extend our feet and toes, and turn our foot outwards. This nerve allows us to walk, sprint, dance; it’s needed for our legs to function. The sciatic nerve also supplies sensation to the foot and much of the lower leg; it enables these areas to feel. This explains why, when the sciatic nerve is inflamed or compressed, the leg can feel ready to give way and burning, tingling, or numb.


Why does sciatica develop?

Because the sciatic nerve is long and meandering it can become compressed, irritated, inflamed at a number of places along its journey. Let’s take a look at two common pressure points…

Disc damage Vs herniation

The spinal column is made from individual vertebrae with a sponge-like disc between each, all strapped together beautifully with ligaments, muscles and fascia so they don’t fall down like a house of biological cards. An in-depth review of Sciatica presented to the British Medical Journal approximated that 90% of sciatica originates from the intervertebral disc.

Each disc consists of two parts; the annulus fibrosis and the nucleus pulpous. The nucleus, as its name suggests, sits at the centre. Its perfect placement and consistency allow motion around its central point. It lets the spine move. The many layers of the annulus then circle the nucleus like the rings of an onion, providing strength and incompressibility.

At the back of the vertebral bodies and discs lies the spinal canal, where the spinal cord runs. Sometimes, due to injury or degradation, a disc can bulge or rupture causing its contents to spill out into the spinal canal. This can compress one of the nerve roots that contributes to the sciatic nerve and trigger sciatica.

Additionally, an even more extraordinarily, it is notable that discs don’t need to be bulging to cause sciatica; chemicals released by an arthritically damaged disc can leak out of the disc causing an inflammation of the adjacent nerves.

Nerve compression – in the Pelvis

Once the nerve roots come together to form the sciatic nerve, this incredible nerve has some distance to travel. From the spine, it wanders through the pelvis, then into, under or over the piriformis muscle in the buttock and down into the leg. This muscle is an important second point of potential compression.

Because the sciatic nerve usually transits through or under the piriformis muscle, when this fibrous bundle is gripped by spasm or tightness it squashes, irritates, and inflames this nerve. Often when we gently push into the buttock over this area a patient will announce, ‘That’s the spot!’ If the piriformis muscle is the symptomatic cause it is appropriately named piriformis syndrome.

Uncovering the cause of sciatica matters because it allows for the fastest, most effective treatment. And speed is a necessity. The longer sciatica remains untreated, the less responsive it becomes. This can be problematic because many health professionals fail to recognise piriformis syndrome, or chemical irritation leading to needless suffering.


At ProBack we are highly trained to diagnose sciatica and hone in on its cause!

ProBack is unique in the U.K. as it adds to its chiropractic foundations our trio of advanced technology: Spinal Decompression Therapy allows us to directly traction disc injuries, K-Laser Therapy increases the rate of anti-inflammatory healing & Shockwave assisted mobilisation helps unravel the functional issues that first create our pain patterns which is super important for long term recovery.


Ready to see how we can help?

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Picture: The sciatic nerve, Credit: Sciatic nerve2.jpg from Wikimedia Commons by K. D. Schroeder, CC-BY-SA 4.0
Last modified : October 20, 2020