Sciatica & Sciatic Nerve
SCIATICA AND THE SCIATIC NERVE
Sciatica commonly refers to pain that radiates along the sciatic nerve and is typically felt in the buttocks, down the back of the leg and possibly to the foot. Sciatica is one of the most common forms of pain caused by compression of the spinal nerves, and the leg pain often feels much worse than the back pain.
Sciatica is actually a symptom and not a diagnosis. The term literally means that a patient has pain down the leg from compression on the sciatic nerve. The diagnosis is what is causing the compression (such as a disc herniation).
The sciatic nerve is the largest single nerve in the human body; it runs from each side of the lower spine through deep in the buttock and back of the thigh, and all the way down to foot, connecting the spinal cord with the leg and foot muscles.
Sciatica pain can result when the nerve roots in the lower spine are irritated or compressed. Most often, sciatica pain is caused when the L5 or S1 nerve root in the lower spine is irritated by a herniated disc. When this happens, pain radiates into the buttocks and back of the thigh and calf, and occasionally may extend down to the foot. Numbness, tingling, and/or a burning or prickling sensation are also common symptoms.
Degenerative disc disease may also irritate the nerve root and cause sciatica, while conditions that mimic sciatica include piriformis syndrome and sacroiliac joint dysfunction. Sciatica may also be felt if the nerve is actually mechanically compressed, such as from spondylolisthesis, spinal stenosis, or arthritis in the spine.
SCIATIC NERVE ANATOMY
The sciatic nerve is the largest and longest single nerve in the human body, about as big around as a thumb at its largest point. The nerve originates in the lower spine as nerve roots exit the spinal cord (through the bones in the spine), and extends all the way down the back of the leg to the toes.
The sciatic nerve is actually a combination of nerves. It is formed on the right and left hand side of the lower spine by the combination of the fourth and fifth lumbar nerves and the first three nerves in the sacral spine. Each nerve exits the spine between two vertebral segments and is named for the segment above it.
- The nerve that exits between lumbar segment 4 and lumbar segment 5 (L4 and L5) is called the L4 nerve root, and the nerve that exits between the L5 and Sacral segment 1 is called the L5.
- The nerves that emerge from the sacral foramen are called the S1, S2 and S3 nerves.
The five nerves group together on the front surface of the piriformis muscle (in the buttocks) and become one large nerve - the sciatic nerve. This nerve travels then down the back of each leg, branching out to innervate specific regions of the leg and foot.
In the lower thigh/above the back of the knee, the sciatic nerve divides into two nerves, the tibial and peroneal nerves, which innervate different parts of the lower leg:
- The peroneal nerves travel laterally (sideways) along the outer aspect of the knee to the upper foot.
- The tibial nerves continue to travel downward towards the feet and innervate the heel and sole of the foot.
The sciatic nerve supplies sensation and strength to the leg as well as the reflexes of the leg. It connects the spinal cord with the outside of the thigh, the hamstring muscles in the back of the thighs, and muscles in the lower leg and feet. As such, when the sciatic nerve is impaired it can lead to muscle weakness in the leg and/or, numbness or tingling.
SCIATICA EXERCISES
Sciatica is a commonly used term for pain originating from the back that is felt along one of several nerve distributions in the buttock, hip, thigh, leg, ankle or foot. Sciatica involves compression or irritation of one or more nerves exiting the lower spine that make up the sciatic nerve. The sciatic nerve branches off as it travels down the lower extremity, and thus pain can be experienced along this route.
Dr. Jeffrey Tucker is a spine specialist who treats the back pain and leg pain associated with sciatica. He recommends exercise as part of a treatment program. The specific exercises recommended will depend on the cause of the sciatica.
THE MAJOR CAUSES OF SCIATICA INCLUDE:
- Sciatica from a herniated disc
- Sciatica from spinal stenosis
- Sciatica from degenerative disc disease
- Sciatica from isthmic spondylolisthesis
SCIATICA FROM A HERNIATED DISC
Herniated discs commonly involve disk material protruding backwards and irritating or compressing a nerve root. Exercises to treat this condition are prescribed according to which positions will cause the symptoms to move up the lower extremity and into the low back.
- For many patients, this is accomplished by getting into a backwards bending position. The low back is gently placed into extension by lying on the stomach (prone position) and propping the upper body up on the elbows, keeping hips on the floor. This should be started slowly, since some patients can not tolerate this position initially.
- This position is typically held from five to 30 seconds per repetition, for 10 repetitions.
After practicing this exercise, Dr. Tucker may recommend a more advanced form of the extension:
- From the prone position, press up on the hands while the pelvis remains in contact with the floor.
- This position is typically held for 1-2 breaths, repeated 10 times.
A similar exercise can be done standing by arching backward slowly with hands on hips if the patient is unable to lie flat. However, the prone position is usually preferred.
These "extension" exercises are done regularly, about every two hours. More importantly, Dr. Tucker may recommend that the person with this condition should avoid getting into a forward flexed (bent over) position. This tends to counteract the effects of the extension exercises.
As the pain works out of the lower extremity, the exercises typically are advanced to strengthen the low back and abdominal muscles to prevent recurrences of the condition.
- To strengthen the low back muscles: In the prone position (lying on your stomach) and hands clasped behind the lower back, raise the head and chest slightly against gravity while looking at the floor (stay low).
- To strengthen the abdominal muscles: For the upper abdominals, lay on the back with one knee bent and one leg straight, fold arms across the chest, tilt the pelvis to flatten the back, and curl-up lifting the head and shoulders from the floor. Do not attempt to lift too high, and bring the head and chest towards the ceiling. For patients with neck pain, place the hands behind the head.
Strenght conditioning as taught by Dr. Tucker may also be encouraged for general body fitness. Walking may or may not be the proper form of exercise for the person with a low back problem. Dr. Tucker will check your gait and help you improve walking problems that may be contributing to your back and leg pain.
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