Severe impairment to lower limbs but normal function in pelvis (m.quadratus lumborum).
Between the anterior and middle layer lies the quadratus lumborum muscle.
Laterally, it blends with the anterior layer at the lateral border of quadratus lumborum.
It emerges from the lateral border of the psoas major just inferior to the iliohypogastric, and passes obliquely across the quadratus lumborum and iliacus.
It forms an arch over the quadratus lumborum muscle.
The lumbar vessels travel through the erector spinae muscles or between the erector spinae muscle and quadratus lumborum muscle.
The main muscles involved include the transversus abdominis, the internal and external obliques, the quadratus lumborum and the diaphragm.
In the lateral tract, the iliocostalis lumborum and longissimus thoracis originates on the back of the sacrum and the posterior part of the iliac crest.
