The L1 vertebra is the upper-most segment of the lumbar spine, which in most people is made up of five vertebrae in the lower back. The top of the lumbar spine joins with the bottom of the thoracic spine, a series of 12 vertebrae that runs from the upper back to the middle back. While the thoracic region serves primarily as structural support for the rib cage and the torso, the lumbar region supports most of the weight of the upper body and is flexible enough to allow for twisting, bending and flexing.
About the lumbar region
The load-bearing role and relative flexibility of the lumbar vertebrae leave them vulnerable to breakdowns associated with wear and tear as we age. The L1 is the first vertebra with lumbar characteristics – longer and wider pedicles, a square-shaped spinous process and larger neural passageways (foramina). In addition, the point where the L1 meets the T12 is known as the transpyloric plane, because the pylorus (exit) of the stomach is found at this level.
Various spinal nerves also originate at or near the L1 vertebra. In general, these nerves innervate the pelvic region and allow for hip flexion. The two primary nerves that originate at the L1 level are:
- The ilioinguinal nerve – performs sensory and motor function for the skin of the upper medial thigh (groin) and the scrotum or labia majora
- The iliohypogastric nerve – performs sensory and motor function for the abdominal muscles and the skin of the lower abdominal wall
The names of these nerves come from the Latin word ilium, which means groin. They intermingle with the subcostal nerve (T12), as well as the nerves that originate in the L2 to L4 levels. The nerve structure at the T12 to L4 level is called the lumbar plexus.
Treatment for L1 conditions
Compression of an L1 nerve, brought on by a herniated disc or other spinal condition, can produce localized discomfort or pain that radiates to the top of the leg or into the groin area. Most of the time, these symptoms can be managed conservatively using pain medication or physical therapy at the direction of your physician. However, if chronic pain begins to affect your quality of life, surgical decompression may become an option.
If this happens to you, consider the alternatives available at Laser Spine Institute. Rather than disruptive traditional open back surgery, Laser Spine Institute offers a variety of minimally invasive outpatient procedures to help you find relief from back pain. Contact Laser Spine Institute to learn more or for a review of your MRI or CT scan.