What movement does the posterior longitudinal ligament limit?

What movement does the posterior longitudinal ligament limit?

• A. Extension
• B. Rotation
• C. Lateral flexion
• D. Flexion

Answer: (D)

This question tests how spinal ligaments constrain movement. The posterior longitudinal ligament runs along the back of the vertebral bodies inside the spinal canal, just in front of the spinal cord. It tightens when the spine flexes (bends forward). As you bend forward, the vertebrae move closer together at the back, pulling the PLL taut and preventing further forward motion. That makes the PLL a restraint on flexion. In contrast, extension is mainly limited by the anterior longitudinal ligament, while rotation and lateral flexion are largely restrained by the facet joints and other ligaments.

This question tests how spinal ligaments constrain movement. The posterior longitudinal ligament runs along the back of the vertebral bodies inside the spinal canal, just in front of the spinal cord. It tightens when the spine flexes (bends forward). As you bend forward, the vertebrae move closer together at the back, pulling the PLL taut and preventing further forward motion. That makes the PLL a restraint on flexion.

In contrast, extension is mainly limited by the anterior longitudinal ligament, while rotation and lateral flexion are largely restrained by the facet joints and other ligaments.