This chapter explores the relationship between biomechanical factors and pathophysiological events for selected spinal disorders. The annulus fibrosus consists of fibers organized in up to 90 concentric bands. The fibers within each band have the same direction; the fibers in adjacent bands run in opposite directions. The fiber direction is angled about 30° relative to the end plate. The end plates are made up of hyaline cartilage and separate the disk from the vertebral body. The vertebral bodies are the principal weight-bearing structures of the spine. They consist of a shell of cortical bone and a core of cancellous bone with a honeycomb structure. The normal annulus is constructed of concentric layers of collagen fibers. The collagen fibers of each distinct layer are parallel, but the fibers of succeeding layers are tilted at angles of about 70° to each other. Disk degeneration has been studied epidemiologically using radiographs, autopsy material, diskograms, and magnetic resonance imaging techniques.