The lumbar supraspinous ligament connects the lumbar spinous process tips, forming the outermost posterior passive restraint. It is often absent or vestigial below L4, replaced by the posterior thoracolumbar fascia. The supraspinous ligament is cut or displaced during posterior lumbar interbody fusion — its preservation in minimal access techniques reduces the instability produced by decompression.
| Origin | L1 spinous process tip (continuous from the thoracic supraspinous ligament) |
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| Insertion | L5 spinous process tip (often absent or replaced by the thoracolumbar fascia below L4) |
| Actions | Resists lumbar flexion at the spinous process tips; the outermost posterior stabilising element |
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Posterior lumbar midline pain reproduced by firm pressure on the spinous process tips suggests supraspinous or interspinous ligament pathology rather than muscular back pain. Injection into the interspinous-supraspinous ligament complex under fluoroscopy can provide both diagnostic and therapeutic benefit.
Posterior midline lumbar pain from supraspinous ligament injury or Baastrup syndrome reproduced by spinous process palpation managed with injection.
