Sciatic nerve pain is caused by the compression of the sciatic nerve. The sciatic nerve is a long nerve in the body that goes from the low back and down through the legs.
This nerve may become compressed due to damage or injury in the spine or injury to the muscles and structures surrounding it in the buttocks. For instance, the piriformis muscle is a tiny muscle in the buttocks. However, it may become tight due to injury or prolonged sitting. This causes the muscle to spasm and press down on the sciatic nerve. Consequently, a person may feel pain in their buttocks that radiates down their legs. This is often referred to as piriformis syndrome.
In other cases, it may be a structural problem in the spine causing pain. A disc in between the vertebrae of the spine may become ruptured or herniated. This causes it to press on the nerves in the spinal cord, such as the sciatic nerve. Again, it may lead to pain in the low back, buttocks, and legs.
Spinal stenosis is another common condition leading to sciatic pain. This is a condition where the spinal canal narrows. Similar to a disc issue, it may compress the sciatic nerve.
Other factors at play also include excess weight, age, and temporary situations, such as pregnancy. Sciatica is common in women in the later stages of pregnancy. Sciatic pain may result from the fetus pressing on the sciatic nerve.
In more rare cases, a tumor, inflammation, infection, or cancer may be causing the pain.