The largest nerve in your body is the sciatic nerve. The sciatic nerve is also your longest nerve, spanning from your lower back past the back of each leg and into your feet and toes.

The complex anatomy of the sciatic nerve means that symptoms of sciatica vary depending on where irritation occurs. Watch: Sciatic Nerve Anatomy Video

Our animated video on the sciatic nerve can help you better understand this important, and sometimes painful, part of your body.

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Video highlights

The sciatic nerve originates as a group of nerve fibers in the lower part of your spine.

These nerve fibers, commonly called nerve roots, leave your spinal canal through openings in your bones called foramen at each level, and on either side, of your lower spine.

Watch Spine Anatomy Overview Video

These nerve roots then join together to become your sciatic nerve. Your sciatic nerve is about as thick as a man's thumb at its largest point.

As pictured above, the sciatic nerve makes its way down your body through the pelvis. The opening it travels through in your pelvis is called the greater sciatic foramen.

Your sciatic nerve runs below your piriformis muscle, so you may experience sciatica symptoms if the muscle spasms.

See What Is Piriformis Syndrome?

Past the piriformis muscle, your sciatic nerve continues through your thigh and behind your knee before dividing into two nerves. These nerves are called the tibial and peroneal nerves, both of which provide nerve function to your lower legs and feet.

A number of lower back conditions can irritate your sciatic nerve, causing pain to radiate along the nerve into your leg or foot. These symptoms are called sciatica, or lumbar radiculopathy.

See Sciatica Causes

Common conditions that cause sciatica include degenerative disc disease and a lumbar herniated disc.

See What You Need to Know About Sciatica

The nature of your sciatica symptoms is determined in part by where your sciatic nerve is irritated in your lower spine.

See When Sciatica Pain Is a Medical Emergency

You may be surprised to learn that pain and/or numbness in your legs or feet originates from a problem in your spine. If you suspect your symptoms may be caused by an irritation to your sciatic nerve, be sure to contact a qualified physician to discuss treatment plans.

See Accurately Diagnosing Leg Pain

Learn more:

Causes of Leg Pain and Foot Pain

Types of Sciatic Nerve Pain