The spinal disc or intervertebral disc is a type of articular disc between the elements of the spine (vertebral bodies). It consists of an outward fibrocartilaginous annulus and a softer nucleus pulposus. Above and under that is a protecting layer of hyaline cartilage. The nucleus of the disc can cause a hernia by breaking through the fibrous ring or pushing it forwards, or to the side, which is called a prolpapse. Depending on its direction and location, the prolapse can cause symptoms like pain, loss of reflexes, and pareses. The reason for this is the pressure that the nucleus is putting on the nerve fibers of the spinal marrow. A complete breakthrough of the nucleus through the fibrous ring is called a protrusion.