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Sciatic nerve


The sciatic nerve is the longest nerve in the human body and the one with the largest caliber. It grows from several nerve branches along the spine, including roots at the last two lumbar vertebrae (L4 and L5) and the first three sacral nerves. It travels down along the buttocks, the posterior of the leg and divides at the back of the knee. It ensures the sensitivity and mobility of the rear part of the thigh. The sciatic nerve is involved in sciatica, causing pain that may extend throughout this route, namely in the buttocks, thigh, leg, feet, and toes. Sciatica is used to define pain experienced during an injury or irritation of the nerve. The term Lumbosciatica is also used when the origin comes from an irritation of the nerve at birth, near the vertebrae. This may be due to a rheumatic disease, infection, nerve compression by a tumor or more often a herniated disc between two vertebrae.


In common Lumbosciatica, the patient feels pain affecting one side of his body, radiating from the lower back to the buttocks and down the back of the leg to the foot. Sensations of electric shock or burning can be felt. Depending on the nerve root damage, the path of the pain may vary slightly.
  • In the case of the infringement of the L5 root, the pain starts in the buttocks, passes through the posterior part of the thigh, descends on the side through the knee and sometimes ends in the big toe.
  • In case of the infringement of the S1 root, the pain runs through the buttocks and down the back of the thigh, knee and leg, continuing to the heel and along the outer edge of the foot to the pinkie toe.


The examination of the patient is necessary to at first characterize the location of pain, the mode of occurrence, the triggering circumstances, and the positions that improve or aggravate discomfort. A clinical examination is also performed to seek the initial location of the pain in the back, then the precise route. A test called the Lasègue test induces pain in the leg of the patient in a supine position. The diagnosis can then be confirmed by an X-ray of the spine, a CT scan or an MRI that sometimes identifies a cause.


The treatment of the pain begins with analgesics or non-steroidal anti-inflammatory drugs. Total rest is not recommended in the case of neuralgia of the sciatic nerve, and rather the doctor recommends slight movements with physiotherapy. In some cases, local injections of corticosteroids improve symptoms. Similarly, some causes are accessible to surgical treatment, namely those involving the decompression of the nerve root. A laminectomy can also be done.


Prevention of sciatica can include:
  • reducing heavy lifting;
  • building muscle in the lumbar region and in the back in general;
  • using a mattress that is comfortable and firm;
  • adopting a correct position while sitting in a chair for a long time;
  • always keeping one's back perfectly straight when sitting (at work, in the car, at a table, in front of the TV, etc..).

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