Bulging Disc Diffuse extension of the disc contour beyond the margins of the disc space involving greater than 50% of the disc circumference. Disc Herniation Displacement of disc tissue through disrupted annular fibers resulting in a localized contour abnormality of the disc that may or may not result in mass effect on adjacent structures. Protrusion Type of disc herniation in which the inner annular fibers are disrupted but outer annular fibers remain intact. Results in focal contour abnormality of disc without allowing disc material to migrate. Extrusion Type of disc herniation in which outer annular fibers are also disrupted allowing internal disc material to extend beyond disc contour and possibly migrate.