The quadratus lumborum muscles originate from the wings of the ilium; their insertions are on the transverse processes of the upper four lumbar vertebrae plus the lower posterior border of the twelfth rib.

The quadratus lumborum muscle originates by aponeurotic fibers into the iliolumbar ligament and the internal lip of the iliac crest for about 5 centimetres (2.0 in).

It inserts from the lower border of the last rib for about half its length and by four small tendons from the apices of the transverse processes of the upper four lumbar vertebrae.

This chain of events can be and often is accelerated by kyphosis, which is invariably accompanied by rounded shoulders, both of which place greater stress on the quadratus lumborum by shifting body weight forward, forcing the erector spinae, quadratus lumborum, multifidi, and especially the levator scapulae to work harder in both seated and standing positions to maintain an erect torso and neck.

Chronic hypertonicity of quadratus lumborum tends to cause low back pain due to its ability to create compressive stress on lumbar segment.

While stretching and strengthening the quadratus lumborum are indicated for unilateral lower back pain, heat or ice applications as well as massage should be considered as part of any comprehensive rehabilitation regimen.

Careful assessment of muscular imbalances and movement impairments by a therapist is recommended in order to address the underlying issues mentioned.