The Sciatic nerve runs from your lower back, through the buttock area, down the back of your leg and to your foot. It is a very large nerve and is commonly affected by low back injuries. Often the pain in your leg is worse than your back. Other sensations are common such as pins and needles or numbness and weakness of the leg. The reason it becomes a problem is because it takes a nerve branch from many different levels of your spine, most of these levels are the ones commonly overstrained or injured.
There are two ways the sciatic nerve is affected.
Firstly, there may be direct pressure from a physical structure trapping the nerve. This is common in the case of a ‘slipped’ or damaged disc. In reality the disc does not slip, but rather a bulge appears on the outer surface. There are other causes of physical pressure such as degenerative changes in the small facet joints, spinal stenosis; a narrowing of the central spinal canal, spondylolisthesis; a slip forward of one vertebrae on the one below and piriformis syndrome; a muscle spasm in the buttock area.
The second way is due to inflammation causing a kind of chemical irritation around the nerve. This may be due to damage to a nearby ligament or muscle.
If you are experiencing leg pain with numbness in the saddle area and difficulty retaining urine or faeces you must go directly to Accident and Emergency.