[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Spine](https://durgical.com/en/anatomy/region/spine/) › Thoracolumbar fascia [Muscular system](https://durgical.com/en/anatomy/system/muscular-system/) · [Spine](https://durgical.com/en/anatomy/region/spine/) # Thoracolumbar fascia The thoracolumbar fascia is a large, diamond-shaped sheet of tough tissue over the lower back that links the back and abdominal muscles. [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=spine&select=thoracolumbar_fascia&side=r) Opens in the Durgical app, no sign-up needed. ## What it is A large, diamond-shaped sheet of tough connective tissue over the lower back, wrapping the deep back muscles in layers. ## What it does Links the back muscles, latissimus dorsi, gluteus maximus and the abdominal wall, so they work together to stiffen and protect the lower back. ## Key points - Its three lumbar layers fuse at the lateral edge of the erector spinae (the lateral raphe), where transversus abdominis and the internal oblique arise - The posterior layer's fibres cross the midline, linking latissimus dorsi on one side with gluteus maximus on the other (described as a posterior oblique sling) - Lumbar hernias pass through the superior (Grynfeltt) or inferior (Petit) lumbar triangles at its edges - It is richly innervated, and its stiffening or injury has been studied as a source of nonspecific low back pain ## Key facts **Where** Back of the trunk from the thoracic region to sacrum and iliac crest; three layers in the lumbar region **Attaches** Posterior layer: spinous processes; middle: lumbar transverse processes; anterior: over quadratus lumborum; latissimus dorsi, gluteus maximus, transversus abdominis, internal oblique **Function** Encloses erector spinae and quadratus lumborum; transmits tension between latissimus, gluteus maximus and abdominal wall to stiffen the lumbar [spine](https://durgical.com/en/anatomy/region/spine/) ## Relations **Deep** Erector spinae and [multifidus](https://durgical.com/en/anatomy/multifidus-muscles/) between the posterior and middle layers; [quadratus lumborum](https://durgical.com/en/anatomy/quadratus-lumborum-muscle/) between the middle and anterior layers; [psoas major](https://durgical.com/en/anatomy/psoas-major/) in front of the anterior layer **Superficial** The [latissimus dorsi](https://durgical.com/en/anatomy/latissimus-dorsi-muscle/) aponeurosis, which fuses with the posterior layer, [serratus posterior](https://durgical.com/en/anatomy/serratus-posterior-superior-muscle/) inferior, then fat and [skin](https://durgical.com/en/anatomy/skin/) **Lateral** Lateral raphe with the origins of [transversus abdominis](https://durgical.com/en/anatomy/transversus-abdominis-muscle/) and [internal oblique](https://durgical.com/en/anatomy/internal-abdominal-oblique-muscle/); the lumbar triangles at the margins **Below** Iliac crest, [sacrum](https://durgical.com/en/anatomy/sacrum/) and posterior [sacroiliac ligaments](https://durgical.com/en/anatomy/sacroiliac-ligaments/), continuous with the fascia of [gluteus maximus](https://durgical.com/en/anatomy/gluteus-maximus-muscle/) ## How to find it In the living back it is not felt as such, but the two rounded vertical ridges of the erector spinae it binds down frame the midline furrow of the loin. In dissection it is the shiny, diamond-shaped aponeurosis under the skin and fat of the lower back, from the lumbar and sacral spinous processes out to the iliac crest. ## On imaging Ultrasound shows the thickness of the layers and how they slide over each other; MRI shows them as dark lines around the muscles. Ultrasound is used to find the compartments for fascial plane blocks. ## Common problems - Strain or irritation can cause low back pain; it is opened and closed in posterior spine surgery. ## How it is diagnosed Exam; ultrasound or MRI if needed. ## Treatment - Physical therapy and exercise. ## Clinical notes - Inferior lumbar triangle (Petit): iliac crest below, latissimus dorsi behind, [external oblique](https://durgical.com/en/anatomy/external-abdominal-oblique-muscle/) in front, floor of internal oblique - Superior lumbar triangle (Grynfeltt): 12th rib above, internal oblique in front, erector spinae and quadratus lumborum behind, floor of the transversus aponeurosis; the more common site of lumbar hernia - Quadratus lumborum and erector spinae plane blocks spread local anaesthetic within its compartments for trunk and abdominal surgery - Closing its posterior layer at the end of open spine surgery helps restore the tension band of the back muscles ## Related conditions - [Mechanical low back pain](https://durgical.com/en/conditions/mechanical-low-back-pain/) - [Sacroiliac joint pain](https://durgical.com/en/conditions/sacroiliac-joint-pain/) ## Test yourself Think of the answer, then tap the question to see it. ## Which muscles arise from the lateral raphe of the thoracolumbar fascia? Transversus abdominis and the internal oblique, where the three lumbar layers fuse at the lateral edge of the erector spinae. ## Which muscles lie between the layers of the lumbar thoracolumbar fascia? Erector spinae and multifidus between the posterior and middle layers; quadratus lumborum between the middle and anterior layers. ## What are the boundaries of the inferior lumbar (Petit) triangle? Iliac crest below, latissimus dorsi behind, external oblique in front, with a floor of internal oblique. ## Which lumbar triangle is the more common site of lumbar hernia, and what bounds it? The superior (Grynfeltt) triangle: 12th rib above, internal oblique in front, erector spinae and quadratus lumborum behind, transversus aponeurosis floor. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/thoracolumbar-fascia/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** fascia thoracolumbalis TA2 2242 **Official Spanish (DeCS)** Fascia toracolumbar DeCS D005205 **English (TA2)** Thoracolumbar fascia **Also called** lumbodorsal fascia · fascia lumbodorsalis · fascia dorsalis · fascia dorsi ## Related - [Iliocostalis](https://durgical.com/en/anatomy/iliocostalis-muscles/) - [Quadratus lumborum](https://durgical.com/en/anatomy/quadratus-lumborum-muscle/) - [Latissimus dorsi](https://durgical.com/en/anatomy/latissimus-dorsi-muscle/) - [Transversus abdominis](https://durgical.com/en/anatomy/transversus-abdominis-muscle/) - [Hip bone](https://durgical.com/en/anatomy/hip-bone/) - [L5 vertebra](https://durgical.com/en/anatomy/lumbar-vertebra-spine-and-pelvis-l5/) Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=5309); [Anatomy, Back](https://www.ncbi.nlm.nih.gov/books/NBK539746/); [Anatomy, Fascia Layers](https://www.ncbi.nlm.nih.gov/books/NBK526038/); Anatomy of the Human Body (20th ed.): Surface Anatomy of the Back (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain. ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/thoracolumbar-fascia/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/thoracolumbar-fascia/