Overview
Your backbone, or spine, is made up of 26 bones called vertebrae. In between them are soft disks filled with a jelly-like substance. These disks cushion the vertebrae and keep them in place. A herniated disk is a disk that slips out of place or ruptures. If it presses on a nerve, it can cause back pain or sciatica.
Symptoms
Back pain that spreads to the buttocks and legs (if herniated disc is in the lower back)
Neck pain that spreads to the shoulders and upper arms (if the herniated disc is in the upper back)
Tingling or numbness
Muscle spasms or weakness
Causes
Aging
Trauma
Genetic predisposition
Diagnosis
X-ray
MRI or CT scan
EMG
Treatment
Activity modification
Anti-inflammatory drugs
Injections
Physical therapy
Surgery
Source: http://www.aans.org/Patient%20Information/Conditions%20and%20Treatments/Herniated%20Disc.aspx