The lumbar is the lower back. The bones (vertebrae) that form the spine in the back are cushioned with small, spongy disks that, if damaged, may bulge.
People can have a herniated disk in any part of the spine, but most herniated disks affect the lower back (lumbar spine). Herniated disks also occur in the neck (cervical spine) and, more rarely, in the upper back (thoracic spine).
When these disks are healthy, they act as shock absorbers to keep the spine flexible. When a disk is damaged, however, it may rupture. This is called a herniated disk, also referred to as a slipped or ruptured disk.