A discogram is a diagnostic procedure used to precisely locate which spinal discs are injured and causing back pain. The discs in your spine are a soft cushion that sits between each vertebra, the bones that make up the spinal column. The disc is a cartilage-like material made up of an outer portion called the annulus which surrounds an inner portion called the nucleus. The nucleus pulposus is a soft jelly like substance that acts like a shock absorber.