What is a key reason the PLL is considered a highly pain-sensitive structure in the spine?

What is a key reason the PLL is considered a highly pain-sensitive structure in the spine?

• A. Proprioceptive density
• B. Dense myelin in fibers
• C. Significant nociceptive innervation
• D. Rich vascular supply only

Answer: (C)

Pain sensitivity in the PLL mainly comes from its abundant nociceptive innervation. The posterior longitudinal ligament is supplied by free nerve endings via the sinuvertebral nerve, which detect harmful mechanical and chemical stimuli. When the PLL is stretched, torn, or inflamed, these nociceptors fire and transmit pain signals to the spinal cord. Proprioceptive input or rapid conduction by heavily myelinated fibers don’t explain why this ligament hurts so readily; nociceptive fibers—often unmyelinated C fibers or lightly myelinated A-delta fibers—are the key. Rich vascular supply can accompany inflammation, but without the direct nociceptive innervation, pain would be much less.

Pain sensitivity in the PLL mainly comes from its abundant nociceptive innervation. The posterior longitudinal ligament is supplied by free nerve endings via the sinuvertebral nerve, which detect harmful mechanical and chemical stimuli. When the PLL is stretched, torn, or inflamed, these nociceptors fire and transmit pain signals to the spinal cord. Proprioceptive input or rapid conduction by heavily myelinated fibers don’t explain why this ligament hurts so readily; nociceptive fibers—often unmyelinated C fibers or lightly myelinated A-delta fibers—are the key. Rich vascular supply can accompany inflammation, but without the direct nociceptive innervation, pain would be much less.