Each vertebral disc is composed of a tough outer layer of cartilage and a more elastic central area. As we age, these discs degenerate and become thinner and weaker. Extra pressure from a fall or from heavy lifting can cause cracks in the outer layers of the discs, allowing the central mass to squeeze out. This kind of rupture can put pressure on the spinal cord or the nerves that branch from it. Herniated discs in the lumbar or sacral regions can put pressure on the sciatic nerve causing pain and discomfort.