Discs act as shock absorbers between vertebrae. When healthy, discs are sponge-like and keep the spine flexible. However, when discs age or are injured, the outer shell can tear and break open, forcing the gel inside the disc out. Although they can occur in any part of the spine, most herniated discs occur in the lumbar (lower back) or cervical (neck area) spine. When they press on nerves, herniated discs can cause pain, numbness, and weakness in the area of the body affected by the nerve.