Important Safety Information (Physician)Lumbar Spine
The lumbar spine consists of the five vertebrae in the abdominal area.
The five lumbar vertebrae are referred to as L1, L2, L3, L4 and L5. The lumbar spine is most frequently involved in back pain because it bears the most body weight and is subject to the largest forces and stresses along the spine.
Lumbar Vertebrae
These vertebrae support the majority of the weight imposed on the spine. The body of each vertebra is attached to a bony ring that consists of several parts. Bony projections on either side of the vertebral body called the pedicles support the arch that protects the spinal canal. The laminae are the parts of the vertebrae that complete the bony arch that surrounds and covers the spinal canal. There is a transverse process on either side of the arch where some of the muscles of the spinal column attach to the vertebrae. The spinous process is the bony portion of the vertebral body that creates the "bumps" down the center of your back.
Intervertebral Discs
Between each vertebra in the lumbar spine are intervertebral discs that act as cushions or shock absorbers and also permit some movement between the vertebral bodies. The discs are flat structures about a quarter to three quarters of an inch thick with contours matching the lumbar vertebrae. Discs have outer rings of tissue called the annulus fibrosis that encircle a soft, white, jelly-like center called the nucleus pulposus. Flat, circular plates of cartilage, called endplates, connect each disc to the vertebrae above and below it. Intervertebral discs compress when weight is put on them and spring back when the weight is removed.
Intervertebral discs make up about one-third of the length of the spine and constitute the largest organ in the body without its own blood supply. The discs receive their blood supply and nutrients through the endplates. The discs expand while at rest allowing them to soak up nutrient rich fluid. When this process is inhibited through repetitive movement, injury or poor posture, the discs become thinner and more prone to injury. This may be a cause of the gradual degeneration of the structure and function of the disc over time, and may also become a source of pain.
The entire spinal column is joined together by ligaments that allow the spine to bend and twist, carrying the weight of the human body with just the right balance of strength and flexibility. In addition to the intervertebral discs, joints between each of the vertebral bodies, called facet joints, allow the individual bones of the spine to move and rotate with respect to each other.
Spinal Muscles
Many muscle groups that move the trunk and the limbs attach to the spinal column. The muscles that closely surround the bones of the spine are important for maintaining posture and helping the spine to carry the loads created during normal activity.
Nervous System
All of the elements of the spinal column serve the purpose of protecting the spinal cord. The spinal cord provides communication to and from the brain, mobility and sensation throughout the body through the complex interaction of bones, ligaments, muscles and nerves.
The spinal cord ends at approximately the L1 level, where it separates into the many different nerve roots. The collection of nerves extending from these nerve roots is called the cauda equina, which means "horse's tail," and describes the continuation of the nerves into the lower body and legs.