Iliocostalis Lumborum
Back
The lumbar part of the lateral erector spinae column — a common contributor to lower back fatigue after prolonged standing or heavy lifting.
Function
Extends and laterally flexes lumbar spine
Origin
Iliac crest, sacrum, thoracolumbar fascia
Insertion
Angles of lower ribs and transverse processes of upper lumbar vertebrae
Innervation
Posterior rami of spinal nerves