All are true about Thoracolumbar fascia except -
Thoracolumbar fascia
-        Lumbar part extends between the 12th rib and iliac crest.
-        It has 3 layers

Anterior layer 

Attachment - Anterior surface of the transverse process of lumbar vertebrae
Position - anterior to quadratus lumborum

Middle layer

Attachment - the Transverse process of lumbar vertebrae
Position - Posterior to quadratus lumborum but anterior to erector spinae.

Posterior layer

Attachment - the Spinous process of lumbar vertebrae
Position - Posterior surface of erector spinae.
-        At the lateral margin of erector spinae, posterior and middle layers unite. Further, anterior layer joins at the later margin of quadratus lumborum. Together they form the aponeurotic origin of transversus abdominis. It also acts as the origin for internal oblique muscle.
Attached to spinous process of lumbar vertebra
Attached to transverse process of lumbar vertebra
The fascia lies posterior to posterior abdominal wall muscles.
Gives attachment to Transversus abdominis and internal oblique muscles