Sciatica is an irritation of the sciatic nerve, the longest and biggest nerve in the body – extending from the lower back all the way down to your toes.
There are three main causes of sciatica:
1. Because the sciatic nerve originates in the low back, one cause is impingement or pressure on one of the nerves forming (or contributing to) the sciatic nerve. Such nerve impingement can be from a malpositioned bone in your lower back or from a bulging disc.
2. A second location where the sciatic nerve can be irritated is in the pelvis at the sacroiliac joint. If you have ever fallen on your hip or pelvis; if you have ever broken a leg bone or had a major foot, ankle, knee or hip joint injury or surgery; if you have a muscle imbalance from performing a particular sport or activity – you may have a rotated pelvis which stresses a sacroiliac joint, and from there the sciatic nerve that runs right in front of it.
3. The third location where pressure can be put on the sciatic nerve is in the buttocks. There are many muscles located there and the sciatic nerve passes underneath these muscles- at least they are supposed to. In some unlucky people the sciatic nerve passes through a muscle called the piriformis muscle. So, if it contracts, it can actually pinch or ‘scissor’ the sciatic nerve. Simple actions such as pressing on the gas pedal while driving, can cause this muscle to contract thereby pressing on the sciatic nerve.