The quadratic lumborum or QL, is one of the tightest an weakest muscles at the lumbopelvic junction
Per the research.
The origin and insertion and function has already been defined.
However, there are a few key other important points to learn about the muscle.
It is one of four “stabilizers” at the lumbopelvic junction.
Accompanied by the transverse abdominis(TVA), external obliques, and
Multifidi, all four muscles play a static and dynamic role in stabilizing.
Per the research by Paul hodges, PT,
He discovered through his RCT’S (randomized controlled trials),
That people with LBP, they were unable to properly contract their TvA
And their firing pattern for the multifidi, was improper.
Meaning when you ask a client who is prone to lift their alternate legs,
They will typically fire their gluteus, the hamstrings then multifidi.
The proper recruitment is multidisciplinary first, the flute max, then hamstrings.
Palate just laterally to the spinous process and ask the client providing your tactile cues to contract multifidi then lift their leg and you should see glute max fire next then hamstrings
I hope this helps and it should provide more in depth understanding
Then what has been previously outlined