Sciatica: Definition, Causes & Symptoms

Instructor: Adrianne Baron

Adrianne has taught high school and college biology and has a master's degree in cancer biology.

We depend on our nerves to tell our brains about our surroundings, but pain can occur when our nerves are not happy. We are going to learn about sciatica and what causes it as well as its symptoms.


You are enjoying playing your favorite sport and all of a sudden you feel this pain shooting down your leg. You attempt to shake it off and continue playing, but it is really getting intense and beginning to get the best of you. Timeout is finally called, and you get a break. Your teammates notice something is wrong based on your face and the fact that you are limping.

You tell them that you have pain going from your butt down your left leg. Your teammate, Tom, tells you that you have sciatica, which is pain and irritation of the sciatic nerve.

The sciatic nerve runs from the lower spine to the butt down to the feet
Diagram showing the sciatic nerve

The sciatic nerve is the last nerve from your lower spine that detects sensations from your butt, down your leg to your foot. You have one on each side of your body. You are finished playing for the day.

Causes of Sciatica

You go to your doctor, Dr. Harris, who confirms exactly what Tom told you. It is indeed sciatica. Your next natural question, is how did I get sciatica? Dr. Harris says that something is causing your sciatic nerve to be irritated.

The most common causes of the irritation are some type of abnormality on one of your vertebrae, which are the bones that make up your backbone, or abnormality of one of your discs that sits between the vertebrae. The discs can herniate, or bulge out, from the backbone and touch the sciatic nerve which causes the nerve to become inflamed and irritated.

Herniated discs press on the sciatic nerve causing sciatica
Diagram showing a herniated disc

Dr. Harris tells you that he would have to do some imaging to determine which one is causing the sciatica. He also tells you that it may be more important to know what changes occurred that caused sciatica to develop. Sciatica can easily happen after any kind of compression injury that compresses your backbone.

There are also some risk factors that Dr. Harris goes over that you could have that may have led to you developing sciatica. These include gaining weight to the point of becoming obese, getting older in age, having diabetes and sitting for extended periods of time. You play sports which decreases the likelihood that it developed from being obese, but you have suffered some injuries over the years as an avid athlete that could have contributed to sciatica. The other possibility that is still being researched is your job since you do a lot of heavy lifting, bending, and twisting repeatedly day after day.

Symptoms of Sciatica

You are taking in what Dr. Harris tells you, but you now want to know what to expect as far as symptoms go. He lets you know that the main symptom is the one that brought you in today, pain! The pain can vary tremendously from one moment to another. There are times when you will feel more of a dull ache and other times when you will feel a very sharp pain shooting from the end in your butt to the ends down in your foot.

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