08/09/2026
Sciatica describes a pattern of symptoms, not the underlying cause. As clinicians, our responsibility is to identify why the sciatic nerve is irritated—not just label the pain.
The sciatic nerve is the largest and longest nerve in the human body. It originates from the L4, L5, S1, S2, and S3 nerve roots, travels through the pelvis, passes beneath (or occasionally through) the piriformis muscle, runs down the back of the thigh, and eventually divides into the tibial and common fibular nerves.
Because of its long course, irritation can occur at multiple points.
Common causes of sciatica include:
✅ Lumbar disc herniation compressing a nerve root.
✅ Lumbar spinal stenosis, particularly in older adults.
✅ Piriformis syndrome, where the muscle irritates the sciatic nerve.
✅ Degenerative changes affecting the lumbar spine.
✅ Trauma or less common conditions such as tumors or infections.
This is why two patients with "sciatica" may have completely different underlying problems—and require different treatment approaches.