Iliocostalis Lumborum (Musculus iliocostalis lumborum)
Educational content only — not medical advice.
Anatomy
The lateralmost column of the erector spinae in the lumbar region, forming part of the common sacrospinalis muscle mass. It arises from the posterior iliac crest and thoracolumbar fascia, ascending to insert by distinct tendons into the inferior borders of the lower six or seven ribs. Working bilaterally, it extends and stabilizes the lumbar spine; unilaterally, it assists in lateral flexion of the vertebral column.
Origin & insertion
From the posterior part of the iliac crest, the sacrum and the thoracolumbar fascia, into the inferior borders of the angles of the lower six or seven ribs.
Action
Extends the vertebral column and maintains erect posture; laterally flexes the spine to the ipsilateral side.
Innervation
Posterior rami of lower thoracic and lumbar spinal nerves (T12–L3).
Clinical notes
Spasm or strain of the iliocostalis lumborum is a primary contributor to mechanical lower back pain and lumbar postural guarding after heavy lifting.
Related structures
Educational references
FAQ
What is the role of the Iliocostalis Lumborum?
The lateralmost column of the erector spinae in the lumbar region, forming part of the common sacrospinalis muscle mass. It arises from the posterior iliac crest and thoracolumbar fascia, ascending to insert by distinct tendons into the inferior borders of the lower six or seven ribs. Working bilaterally, it extends and stabilizes the lumbar spine; unilaterally, it assists in lateral flexion of the vertebral column.
Why is the Iliocostalis Lumborum clinically important?
Spasm or strain of the iliocostalis lumborum is a primary contributor to mechanical lower back pain and lumbar postural guarding after heavy lifting.
Source & license
BodyParts3D, © The Database Center for Life Science licensed under CC Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/). license details