What Is It?
The disks in your spine, called intervertebral disks, are thin, oblong structures that serve as cushions between the bones of your back (vertebrae). Each disk is made of a soft gel core surrounded by a tough, fibrous outer shell. This structure allows the disk to be firm enough to maintain the space between the vertebrae, but soft enough to compress when the spine flexes during bending, leaning and turning sideways.
In some people, mostly middle-aged adults, a disk's tough outer shell develops an area of weakness or a small tear. When this happens, part of the disk's soft inner core can bulge out of its normal position (herniate), producing a condition called a herniated disk.