The sciatic nerve is the longest nerve in the human body, and it runs from the lower back down the back of each leg all the way down to the feet. The nerve branches off in several areas, and if the nerve becomes compressed at any point along its length, it can cause pain at the site of compression or anywhere else along the length of the sciatic nerve. The nerve runs through the hips and buttocks as well, and these are common locations where compression of the sciatic nerve is likely to occur. Herniated discs in the spine can also cause sciatic pain.
Nerves carry electrical impulses to different parts of the body, and when those nerves get compressed for any reason, the impulses may be altered or blocked entirely. A pinched nerve can cause pain, numbness, or even a loss of limb control. Since the sciatic nerve services much of the lower body, any of the area from the lower back down can be affected by a pinched sciatic nerve. When the nerve becomes compressed, the resulting condition is called sciatica. The nerve originates in the spine, making it a spinal nerve as opposed to a cranial nerve that originates in the head. Since its positioning starts in the spine, the sciatic nerve is prone to compression due to a herniated disc.
A herniated disc occurs when a spinal disc that sits between two vertebrae ruptures, causing pressure on the sciatic nerve. A sufferer of a herniated disc may feel pain down the length of the leg, in the hips, buttocks, or lower back as a result of the compression on the nerve. A herniated disc injury usually heals on its own, but sometimes surgery will be necessary to fix the problem. If neurological issues arise from the damage done to the nerve, a doctor may consider surgery as well, though this is considered a last resort. The neurological issues caused by the nerve damage must be severe and/or chronic. Surgery will often be considered if the compression is due to other causes as well, not just a herniated disc.
The nerve may run through clusters of muscles or other tissue, and it can become compressed in these areas as well. People who sit for long periods of time often complain of sciatica, and athletes may experience sciatica as a result of muscle tightness. A lack of regular exercise will create weaker muscles that are more likely to tire quickly; when a muscle tires, it tends to tighten, which can put pressure on the sciatic nerve.