Sciatica is a term often used to describe any type of lower back pain.
In fact there are many causes of lower back pain, of which sciatica is just one. Sciatica refers to pain in the lower back, buttock or leg that is caused by irritation to the sciatic nerve.The sciatic nerve is made from bundles of nerve fibres that exit the spinal cord in the lower part of the spine. These combine to form a thick rope-like nerve which then travels deeply through the pelvis and buttock, down the back of the thigh before splitting into several smaller nerves which spread out below the knee and into the foot.
Nerves have two main jobs in the body. Firstly they allow us to feel things. When there is sensory stimulation to a part of our skin, it is the nerves that sense this and send a signal to our brains that cause us to perceive the sensation. Secondly nerves produce power in our muscles by carrying signals from our brains which tell our muscles to contract or relax. Therefore if a nerve is injured or the signal is not being transmitted properly, the result can be reduced sensation (numbness, tingling) or reduced power (weakness). So in cases of sciatica, this can mean that as well as having pain radiating into your hip or leg, you might also feel numbness or weakness in the leg.
So how does the sciatic nerve become irritated? The nerve has a specific pathway that it follows down the limb, and along this pathway there are areas where certain structures can close in, causing the nerve to be trapped or pinched. It can happen from a single specific incident such as bending or lifting, or it can happen gradually over time, for example due to poor posture. Structures that commonly cause nerve irritation are the discs in the lower back that can bulge out and press on the nerve, the bony joints of the lower spine between which the nerves pass, as well as some of the muscles in the lower back and hip that can tighten and squeeze the nerve as it courses through.
Your physiotherapist will perform a thorough assessment of these structures and your movement patterns to identify the cause of the sciatica and will implement a treatment plan. This should relieve the nerve irritation and pain. Your physiotherapist will also educate you on how to manage your back to prevent future flare ups.