Vertebrae Degeneration, Stages of Prolapsed Disc; Natural cast model illustrates degenerative changes to the vertebrae and intervertebral discs of the lumbar spine in five progressively serious degrees. From healthy disc and vertebrae all the way to very severe degeneration and bony constriction of the left intervertebral foramen with pressure on the spinal nerve root L5. 9" length mounted on base. Now included with all 3B Scientific Anatomy models is the 3B Smart Anatomy app. This app allows users to register their 3B item to extend the warranty from 3 to 5 years plus free 1 year access to the 3B Smart Anatomy app which includes 23 Anatomy lectures, 117 interactive models and 39 quizzes.