Sciatica Biology: the Sciatic Nerve

  I wouldn't dream of baffling everyone with all the Latin names for all the parts of your body that are involved in (or may be involved in) sciatica — I am just as baffled myself! Instead I will just skim over some of the more technical parts, just enough so that you will understand a little more of what your physician is talking about when you go for a diagnosis.

If you really want to know more, then there are plenty of good books available.

So! Let's look at the simple side of Sciatica Biology.

Sciatic Nerve Formation

The Sciatic Nerve (also sometimes called the ischiatic nerve) is the longest nerve in your body. There are two of them, starting in your lower back, then each one runs through one of your buttocks and down into your thigh and then down the remainder of each leg.

The sciatic nerve is actually a bundle of nerves that emerge from various places in your spine:

The part of your sciatic nerve that emerges from between your lumbar segments L4 and L5 is called the L4 nerve root. The part that emerges from between your lumbar L5 and sacral S1 is called the L5 nerve root. The parts of your sciatic nerve that emerge from various places in your sacrum are called the S1, S2, and S3 nerves.

"Lumbar" refers to your lower back -- where it normally curves inwards. The "Sacrum" is the large fused bone just below that, at the top of the cleft between your buttocks.

Biology of Sciatica

The precise nature of your sciatica pain and its condition depends on the precise nature of the irritation of your sciatic nerve, and its precise location. Some of the different ways that sciatica can present itself are:

Sciatica Radiculopathy

But what causes the problems for L4, L5, and S1? Have a look at a more detailed description of the causes of sciatica, but note for now that it can be problems with one of your discs (or possibly a tumour). The discs in your spine are like shock absorbers that also allow your back to bend and swivel.

As you grow older, the discs can become weak or damaged, and a disc can bulge out or even split, and put pressure on your sciatic nerve.

The clinical diagnosis of sciatica may be referred to by your doctor as a radiculopathy; that simply means that a protrusion from one of the discs in your spine is putting pressure on the nerve root (properly called the radicular nerve) – the start of your sciatic nerve – in the lower part of your back.

The information on this page could be useful if you talk to a healthcare professional during a diagnosis session.