Trunk (thorax, abdomen, back)
Thoracolumbar Fascia, Anterior Layer
Fascia thoracolumbalis, lamina anterior
- Origin
- Covers the anterior surface of the quadratus lumborum muscle, arising from the transverse processes of the lumbar vertebrae
- Insertion
- Attaches caudally to the iliac crest and cranially to the inferior border of the 12th rib and the lateral arcuate ligament of the diaphragm; fuses laterally with the middle layer
- Function
- Envelops the anterior surface of the quadratus lumborum muscle and forms part of the lateral arcuate ligament, an attachment arch of the diaphragm
- Innervation
- No independent motor innervation (connective tissue structure, not contractile tissue)
- Movement & chain
- Connects lumbar vertebrae to the 12th rib forming a rigid fascial anchor for deep abdominal wall muscles.
- Palpation
- Deep anterior to quadratus lumborum; not accessible to manual examination.
- Clinical
- Forms the lateral arcuate ligament of the diaphragm; separates the perinephric space from posterior paraspinal musculature.
- Segmental innervation
- T12–L3 (posterior rami of spinal nerves)
- In clinical practice
- Ergonomic patient repositioning (log-roll technique in spinal trauma) and pressure offloading; maintain neutral spinal alignment in bedridden patients.
- Region in the model
- Trunk (thorax, abdomen, back)