Immunohistochemical demonstration of nociceptors in the capsule and synovial folds of human zygapophyseal joints.

Substance P, a physiologically potent neuropeptide, is considered to participate in nociceptive transmission of nerve impulses. Substance P immunofluorescent nerves are demonstrated in the inferior joint recess capsule and its synovial folds in human lumbosacral zygapophyseal joints. This may have clinical significance in spinal pain.