The lumbar spine (lower back) is a remarkably complex structure. The L4-L5 are the two lowest vertebrae in the lumbar spine, and together with the attached disc, joints, nerves and soft tissues, it provides a variety of functions, including supporting the upper body and allowing motion in multiple directions.
However, with its heavy load and range of flexibility, the L4-L5 segment is also prone to developing pain from injury and/or from degenerative changes, such as:
- The L4 vertebra can slip forward over the L5 vertebra, impinging the nerve root and causing lower back and/or leg pain (sciatica)
- The L4-L5 disc, in between the L4 and L5 vertebrae, can herniate or degenerate, leading to possible leg pain (sciatica) and/or lower back pain
- The two joints called facet joints (or zygapophyseal joints), which connect to the L4 and L5 vertebrae in the back of the spine, can allow abnormal amount of motion and/or develop osteoarthritis
- The back of the L4-L5 segment has a nerve that passes through it, from inside the spinal canal down through the back of each leg (as part of the sciatic nerve). This nerve is called the L4 nerve root. If any in inflammatory proteins from inside the disc herniate and come in contact with this nerve, or if anything presses against it, pain can travel down the nerve (called a radiculopathy, or sciatica).
Causes of L4-L5 Pain
Common lower back problems that cause pain in segment L4-L5 include:
- L4-L5 disc herniation: The most common place for a disc to herniate is at L4-L5 or L5-S1 because of the amount of weight these segments carry and due to their range of motion. When the disc herniates, the inner portion leaks out and touches the nearby nerve root, causing pain to radiate in the lower back and/or down the leg.
Updated: 10/29/2013
Continue reading the original article from Spine Health here.