Lumbar Spine

The lumbar spine is the lower part of the vertebral column, located between the thoracic spine (mid-back) and the sacral spine (pelvis). It comprises 5 vertebrae, each designated L1 through L5 (from superior to inferior).

General Characteristics of Lumbar Vertebrae

Each lumbar vertebra shares common characteristics:

Vertebral Body: The bodies of the lumbar vertebrae are the largest among the spinal column. They are kidney-shaped when viewed from above. The bodies increase in size moving down the spine, as each vertebra must bear more weight.

Vertebral Foramen: This is the hole through which the spinal cord passes. It is larger in the lumbar region than in the thoracic region due to the need to accommodate the cauda equina, a bundle of spinal nerves and nerve roots.

Spinous Processes: These project posteriorly from the vertebrae and are short and broad. They serve as attachment points for muscles and ligaments.

Transverse Processes: These project laterally from the vertebrae and serve as attachment points for muscles and ligaments. Unlike the thoracic vertebrae, they do not articulate with the ribs.

Specific Characteristics of Lumbar Vertebrae

The 5 lumbar vertebrae all have unique characteristics, mainly dealing with their size and robustness to support body weight:

  • L1-L5: These vertebrae are significantly larger and stronger than the vertebrae in the thoracic and cervical regions. They are designed to bear the body’s weight and the stresses placed on the spine during lifting, carrying, and other activities.

The lumbar spine allows for significant flexibility and range of motion, including bending and twisting to a degree. However, this flexibility, combined with the weight-bearing role of the lumbar spine, also makes it a common area for injury. Intervertebral discs between each pair of lumbar vertebrae provide cushioning, support, and flexibility. These discs are thicker than those in other regions to absorb the increased pressure.