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Anatomy of The Lumbar Back Muscles-Quadratus Lumborum

The quadratus lumborum consists of medial and lateral fibers that are enclosed by the anterior and middle layers of the thoracolumbar fascia. The medial fibers attach “from the ilium to the anterior surface of the transverse processes of the lumbar vertebrae and other fibers travel from the transverse processes to anchor onto the twelfth rib.

The lateral portion of the muscle, which belongs to the global system, spans the lumbar area, attaching on the lateral ilium to insert into the twelfth rib without attachment to any vertebrae”. Because of the attachments of the medial portion of the muscle to the vertebrae, it may be capable of providing some segmental stability. McGill et al.  provided evidence of increased muscle activity with increasing spinal compression during a symmetrical bucket-holding task.

Andersson et al. It found increased activity of the muscle during full forward flexion. The medial fibers of the quadratus lumborum are considered to be part of the local stabilizing system because of its segmental attachments and, therefore, are able to provide segmental stability.

The lateral fibers of the quadratus lumborum are considered to be part of the global stabilizing system, because there is no attachment to any vertebrae . McGill et al. It provided evidence of the quadratus lumborum being “more active than other muscles during isometric side support postures.”He has suggested the use of “horizontal side support” or side bridging as an exercise to incorporate for training. The quadratus lumborum provides lateral stabilization of the lumbopelvic region.

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