Low Back Pain

Vertebral Column

At the core of the low back is the lumbar vertebral column, consisting of five vertebrae, labeled L1 to L5. These vertebrae are the largest and strongest in the spine, designed to bear the brunt of the body's weight and endure substantial stress. Each vertebra consists of a vertebral body, which supports weight, and a vertebral arch, which protects the spinal cord.

Intervertebral Discs

Between each pair of lumbar vertebrae are intervertebral discs, acting as shock absorbers. These discs have a tough, fibrous outer layer called the annulus fibrosus, and a gel-like center known as the nucleus pulposus. The discs allow for flexibility and movement while cushioning the vertebrae.

Joints

The low back contains several types of joints that are crucial for its function and movement:

• Facet Joints (Zygapophyseal Joints): These synovial joints are located at the back of the spine, where each vertebra articulates with the one above and below it. Facet joints facilitate the sliding and gliding motions of the vertebrae, contributing to the spine's flexibility and movement.
• Intervertebral Joints: Formed by the intervertebral discs and the adjacent vertebral bodies, these cartilaginous joints allow for slight movements between vertebrae and act as shock absorbers.
• Sacroiliac Joints: Located where the sacrum (the triangular bone at the base of the spine) meets the iliac bones of the pelvis, these joints transfer weight and forces between the upper body and the lower extremities. They are crucial for stability and play a significant role in movements involving the hips and pelvis.

Ligaments and Muscles

A complex network of ligaments and muscles supports the lumbar spine. Key ligaments include the anterior and posterior longitudinal ligaments, which run along the front and back of the vertebral bodies, respectively, and the ligamentum flavum, which connects the laminae of adjacent vertebrae. The muscles, such as the multifidus and erector spinae, provide dynamic stability and movement, allowing for bending, twisting, and lifting.

Neural Structures

The spinal cord ends at the L1-L2 level, continuing as the cauda equina, a bundle of nerve roots that innervates the lower extremities and pelvic organs. These nerve roots exit through foramina (openings) between the vertebrae, and any compression or irritation of these nerves can lead to symptoms like pain, numbness, or weakness in the lower body.