A herniated nucleus pulposus, commonly called a slipped disc, occurs when the soft gel-like center of an intervertebral disc pushes out of its normal position. It most often affects the lower (lumbar) spine, where body weight is greatest. Common symptoms include pain radiating into the buttocks and legs. Diagnosis involves physical examination, neurological tests, and imaging like MRI, which can clearly show the herniated disc material compressing spinal nerves.