| External Tissues |
| • Skin |
| • Subcutaneous tissue |
| • Fat |
| Joints |
| • Capsules of facet and sacroiliac joints |
| Ligaments |
| • Longitudinal spinal |
| • Posterior interspinous |
| • Sacroiliac |
| • Ligamentum flavum (minimal pain fiber innervation) |
| Periosteum |
| • Vertebral bodies and arches |
| Dura mater |
| Epidural fibro-adipose tissue |
| Annulus fibrosus |
| Arterioles |
| • Of spinal and sacroiliac joints |
| • Of vertebral cancellous bone |
| Veins |
| • Epidural |
| • Paravertebral |
| Paravertebral muscles |
| • Pain fibers in perivascular connective tissues |
