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  • Dr. Stefano Bozzo

What is Sciatica?

Sciatic Nerve Anatomy

Sciatica is so common you have likely heard of it or maybe even had it before. While sciatica does involve leg pain (but not always back pain), it is often used to describe various back and leg symptoms. Sciatica is a symptom, like saying I have a cough, which does not tell the whole story. Like a cough, there are several reasons why a person can have sciatica, and knowing the cause is essential to determine the best approach to therapy.

The sciatic nerve is the largest in the body. Five spinal nerve roots come together to form two nerves (the Tibial and Peroneal nerves), which are wrapped in a sheath to form the sciatic nerve. It travels out of the pelvis and down the leg, providing muscle innervation and skin sensation to various areas.

Sciatic Innervations

Sciatica is pain radiating from the buttock down the back of the leg along the sciatic nerve. Sciatica can be caused by a disturbance (usually compression) anywhere along the sciatic nerve. Symptoms of sciatica will be different depending on the cause and location of the disturbance. Sciatica can come on suddenly or slowly. It often has achy and sharp components, radiating from the middle of the lower buttock, down the back, side, or front of the thigh. It may extend below the knee to the foot. Low back pain may or may not be present, and the intensity of low back pain varies. It is most common in those in their 40s and 50s and is usually unilateral (one-sided), although it may present bilaterally (on both sides) in some cases.


There are many causes of sciatica, but lumbar disk herniation and degenerative spine conditions are the most common.

Spinal discs are soft structures between each spine bone (vertebra). Lumbar discs refer to those discs in the low back. Discs are made of an inner part (the nucleus) held in by layers of ligaments called the annulus fibrosis. A lumbar disc herniation occurs when the outer layers of the annulus fibrosis tear allowing the inner nucleus to squeeze out. When this happens, it can compress a nerve root, resulting in pain or numbness in parts of the leg or foot.

In cases of degenerative spine diseases such as osteoarthritis, a condition known as foraminal stenosis may cause nerve root compression. In this case, the space through which the nerve root exits the spine becomes narrowed. Stenosis can happen in various areas of the spine; depending on the location, symptoms can be unilateral or bilateral.

While both lumbar disc herniation and spinal stenosis may cause sciatica, it can be challenging to determine which. Even more importantly, strategies that help reduce the pain from lumbar disc herniation can worsen spinal stenosis pain. So it is essential to have a thorough assessment to determine the cause and best treatment options.

Piriformis and Sciatic Relationship

Another cause of sciatica called piriformis syndrome may account for up to 6% of cases. The piriformis is a small muscle in the buttock region. In piriformis syndrome, the piriformis muscle compresses the sciatic nerve. The sciatic nerve usually runs under the piriformis. However, part of it may run through the piriformis in 12.2% of people and over the piriformis in 0.5%. The sciatic nerve can become compressed or entrapped as it passes through the piriformis or by scar tissue from a trauma to the buttock region. Piriformis syndrome commonly starts as gradually worsening buttock pain, aggravated by sitting. The radiating leg pain classic of sciatica is uncommon, but numbness and tingling in the lower leg and foot may develop.


Standard initial treatment is to reduce pain. In general, an excellent first step in treating acute sciatica cases is to find positions that relieve leg pain. These positions will be different depending on the patient, but in my experience, the Z-lye is a good relief position worth trying in most cases.

If piriformis syndrome is suspected, stretching the piriformis is a good starting point. Therapy is effective in most cases consisting of stretching the muscles and strengthening the pelvis and hip regions.

Most cases of sciatica resolve without the need for treatment. If symptoms worsen, negatively impact your daily life, or are severe, seek help from a licensed health care professional who can assess and diagnose your sciatica, such as a chiropractor, family physician, nurse practitioner, or physiotherapist.

If you think you or someone you know has sciatica, and are wondering if chiropractic care can help you. Please email me, I am happy to answer your questions.


This article is for information purposes only. If you are experiencing pain, consult a health care professional, such as a chiropractor to assess your needs and identify a course of action that is right for your specific condition.


  1. Ropper AH, Zafonte RD. Sciatica. N Engl J Med. 2015 Mar 26;372(13):1240-8. doi: 10.1056/NEJMra1410151. PMID: 25806916.

  2. Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2009). Clinically Oriented Anatomy (6th ed.). Lippincott Williams and Wilkins.

  3. Johnson,R. (2019). Approach to hip and groin pain in the athlete and active adult. In Jonathan Grayzel (Ed.), UpToDate. Retrieved February 25, 2021, from

  4. O’Brien, M. (2000). Aids to the Examination of the Peripheral Nervous System (4th ed.). Saunders.



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