The lumbar spine consists of 5 lumbar bones (vertebrae) stacked on top of the sacrum. The body of the vertebra is cylindrical mass of solid bone that is the weight bearing portion of the vertebra. Extending back from each side of the body are pillars of bone called pedicles. Two plates of bone called laminae arch between the pedicles, thus enclosing the spinal canal, which contains the nerves that travel to the legs. At the junction between the lamina and pedicle, behind the nerves, are smooth projections called facets, the joints of the spine. Between the vertebrae are discs, or cushions, which act as shock absorbers, and allow for motion and flexibility. Ligaments and muscle are attached to the vertebrae at various points to provide strength and stability and to control motion. The lumbar spine serves three primary functions: 1) to provide support for the body; 2) to protect the nerves that go to the legs, bowels, and bladder; 3) to allow motion of the torso in relation to the pelvis.
The lumbar disc has an outer tough ring that encloses a softer, spongy center. As part of normal aging, the disc undergoes a gradual wear and tear process referred to as Adegeneration, characterized by the gradual loss of water, decrease in height, stiffening of the disc, and bulging of the ring of the disc. This is a normal process that occurs in all adults, and is usually unassociated with any pain. Most adults older than 50, and many in their 40’s have some degree of disc degeneration, which appears on an MRI scan as a darker appearance of the disc. Often the only symptom is a gradual loss of range of motion, often not even noticed because it occurs so slowly when you’re 80 years old, your back is not as flexible as when you were 20, but it is not necessarily painful.
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