The Posterior Longitudinal Ligament (PLL) is a fibrous connective tissue structure found in the human spinal column. It runs along the posterior (back) aspect of the vertebral bodies, extending from the craniovertebral junction down to the sacrum. It is part of the spinal ligamentous complex, along with the anterior longitudinal ligament, ligamentum flavum, and interspinous ligaments.
The primary function of the PLL is to provide stability and support to the spine, securing the alignment and positioning of the vertebrae. It helps prevent excessive movement, hyperextension, and posterior disc herniation by limiting backward bending (extension) of the spine. It plays a crucial role in maintaining the overall structural integrity of the spinal column.
The posterior longitudinal ligament is composed of dense collagenous fibers that are arranged in a longitudinal manner. It is softer and more elastic compared to the anterior longitudinal ligament, allowing for slight flexibility while maintaining its primary role of limiting extension.
In addition to its mechanical function, the PLL also acts as a protective barrier to prevent injury to the spinal cord and nerve roots from excessive posterior movements or compression. It serves as an important anatomical landmark for surgeons during spine surgeries and plays a significant role in determining the surgical approach and strategy.
In summary, the posterior longitudinal ligament is a strong fibrous structure located at the back of the vertebral bodies, serving to stabilize the spine, limit extension, and protect the spinal cord and nerve structures.
