LUMBAR SQUARE: ORIGIN, INSERTION, FUNCTIONS, DISORDERS - ANATOMY AND PHYSIOLOGY - 2025

The quadratus lumbar is a muscle in the trunk of the body. Its name comes from the Latin musculus quadratus lumborum or also costalis lumborum. It is located specifically in the posteroinferior and lateral portion of the lumbar band.

It is a paired muscle, that is, there is one on each side of the spinal column, at the level of the lumbar vertebrae L1 to L4. The quadrilateral lumbar muscle owes its name to the quadrilateral shape it presents and the area where it is located. Its structure is flattened and is made up of the interweaving of its fibers, which are oriented in three directions.

Graphic representation of the location of the quadratus lumbar muscle. Source: Wikipedia.com

Two types of fibers are oriented transversely and one type of fiber does so obliquely or collaterally. The fibers are called costotransverse, iliotransverse, and iliocostals. Each has an insertion site that supports the muscle. The fibers run from the bottom up, with an inclination towards the interior or center of the body.

These muscles are strategically located to allow certain movements, among them: inclination of the trunk towards one side of the body (ipsilateral), contributes to the extension of the spine, also provides stability in the frontal and sagittal planes.

Finally, it participates in the expiratory movement during respiration (descent of the twelfth rib) and elevates the hemipelvis on the side where the contraction occurs.

characteristics

It is a deep located muscle. It is located in front of the spinal muscle mass. It has a quadrilateral and flat shape. The human body has two lumbar square muscles, one on each side of the spine at the level of the lumbar vertebrae (L1-L4). Its origin and insertion is fulfilled symmetrically on both sides of the body.

These muscles do not have great power, but they do have great resistance and precision during movement or sustained effort. They can act jointly or unilaterally, depending on the movement.

According to its origin and insertion, the quadratus lumbar muscle is related to the pelvis, the spinal column and the twelfth rib.

It has muscle fibers also called fascicles arranged in three directions, these are called: costotransverse, iliotransverse and iliocostals.

The costotransverse or lumbocostal are a set of fibers that come out of the transverse processes of the lumbar vertebrae (from L4 to L1). They all converge on the lower and inner part of rib number 12, on the corresponding side (right or left).

The iliotransverse or iliolumbar are another group of fibers that come out from the external lip of the iliac crest, to distribute and join the transverse processes of the lumbar vertebrae, in the same previous order (from L4 to L1).

Whereas, the iliocostals are fibers that come from the pelvis (outer lip of the iliac spine) to the lower inner portion of the twelfth rib.

Origin

Each quadratus lumbar muscle originates from the medial third of the outer lip of the iliac crest (pelvis) and some of its fibers originate from the ileolumbar ligament (ligament that connects the spine to the pelvis).

Insertion

The muscle ends its journey by strongly joining the twelfth rib, but during the journey it has points of insertion at the level of the apices of the lumbar vertebrae (from L4 to L1).

Innervation

Several nerve fibers reach these muscles, which are the T12 spinal nerve or also called thoracic nerve 12, and branches of the L1-L4 spinal nerves (corresponding to the lumbar plexus).

Irrigation

The quadratus lumbar muscle is supplied by the lumbar arteries and also by the ascending branch of the iliolumbar artery.

Function of the quadratus lumbar muscle

It has several functions. With the pelvis fixed and a single muscle acting, it serves to tilt the trunk of the body in an ipsilateral position (flexion towards the same side of the muscle that is in action). While the muscle on the opposite side is stretched.

On the other hand, the strategic location of these muscles on each side of the spine contributes to its extension. In this case, both muscles contract at the same time, allowing the trunk to be in an upright position.

It also participates in the movement of expiration, therefore it is considered an accessory muscle for this function, because when the air is exhaled during breathing, the twelfth rib to which the muscle is inserted, lowers its position.

It also maintains the stability of the spine, both in the frontal plane and when rotating to the sagittal plane. This action is carried out together with other muscles of the abdomen.

Finally, it allows the individual to stand on one leg, without the pelvis falling the other way. In addition, together with the psoas muscle, it is capable of raising the hemipelvis on the side where the contraction occurs.

Syndromes

When one or both muscles are affected, they can cause moderate to severe pain in the lower back.

It can be affected by many causes, among them we can mention: subjecting the muscles to excessive tension, this can happen when adopting bad postures when sitting. This action weakens other back muscles, therefore the quadratus lumbar is recharged.

It can also be affected when there are inequalities in the size of the legs or deformities of the spine. In this case, the quadratus lumbar tries to compensate for this failure to stabilize the trunk, overloading itself.

- Low back pain

This muscle is often over-tense (muscle contracture), causing a painful clinical picture, called low back pain. It has been proven that a large part of low back pain is due to involvement of the quadratus lumbar.

When the muscle is over-tensioned, it can even make breathing difficult, due to the stiffness produced in the thoracic region.

Characteristics of the affectation

This affectation hinders the movement of the trunk due to the pain that it produces. Allows sitting and walking but with difficulty.

The pain usually radiates to the sacroiliac joints, testicles, and the path of the sciatic nerve.

The greater trochanter is hypersensitive.

It is difficult for the patient to get up from the chair or to sit up when lying on his back (supine position) or to turn while lying down or to stand up without support. However, it is possible to walk on all fours (on all fours).

A certain burning sensation may appear in the legs, radiating to the feet with a certain tingling in the calves.

The pain is accentuated by coughing or sneezing or standing for a long time.

- Shortening of the muscle

This results in the generation of certain anomalies, such as: uneven hips, that is, one side of the hip is higher than the other (asymmetric or tilted pelvis), lumbar hyperlordosis (increased lumbar curvature), lumbar scoliosis (deviation of the spine).

Specialists can perform a muscle length test to assess whether or not there is shortening of either of the two muscles.

To do this, take the patient by the ankle and the shoulder and try to rotate the trunk towards the opposite side very slowly, as far as the patient resists. The position is held for 6 sec. The action is repeated on the opposite side.

If the patient cannot perform this action it is said to be a positive test for muscle shortening. If, on the other hand, the trunk flexes without problem on both sides, it can return to the starting position and no imbalance is observed in the pelvis and ribs, the shortening test is negative.

- Pelvic girdle myofascial pain syndrome (MDS)

It is defined as a painful non-inflammatory musculoskeletal involvement. Mainly the iliopsoas muscle, the quadratus lumbar muscle and the pyramidal muscle are affected. Palpable trigger points usually appear in the affected area.

Trigger points

They are muscle knots that represent a hyper-irritation pain zone.

Trigger points cause pain when pressed, but they can also radiate pain to other nearby anatomical areas, creating satellite trigger points, especially in the gluteal minor area. This picture is sometimes confused with sciatica (compression of the sciatic nerve).

Exercises for muscle relaxation and strengthening

To improve the affectations of the quadratus lumbar, a series of exercises can be performed that are quite simple.

Those who practice yoga recommend certain positions, such as: ardha chandrâsana, the mermaid, utthita trikonâsana, parivrtta janu sirsâsana, parivrtta trikonâsana, jathara parivartanâsana, apanâsana, face up and side bent, parshvatan kumbhakâsana, purvotâsana. See the following figure:

Image taken from the following source: Costa A. Cuadrado Lumbar. Basic study of anatomy applied to yoga. Synthesis Yoga. Teacher training school. Available at: cuerpomenteyespiritu.es

Most help stretch, relax and flex each quadratus lumbar muscle, while the latter two help strengthen them.

References

1. Costa A. Lumbar Square. Basic study of anatomy applied to yoga. Synthesis Yoga. Teacher training school. Available at: cuerpomenteyespiritu.es
2. Rodríguez A, Zuil J, López J. Specific treatment of the quadratus lumbar muscle in low back pain: study of 14 cases. Physiotherapy 2003; 25 (4): 233-43. Available at: elsevier.es.
3. Orellana M. Application of the Pilates method in people who present muscular imbalances in the lumbar area in subacute or chronic stage. Dissertation to qualify for a Bachelor of Physical Therapy degree. Quito 2014.Available at: puce.edu.ec
4. «Square lumbar muscle» Wikipedia, The Free Encyclopedia. 6 Mar 2019, 16:28 UTC. 2 Sep 2019, 10:29 org.
5. Gil E, Martínez G, Aldaya C, Rodríguez Myofascial pain syndrome of the pelvic girdle. Rev. Soc. Esp. Pain, 2007; 14 (5): 358-368. Available at: scielo.isciii.es
6. Velázquez I, Muñoz M, Velázquez L, García P, Zénner A, Ruiz J. Comparison of results obtained in the treatment of myofascial pain of the pelvic girdle with botulinum toxin alone and associated with lidocaine. Soc. Esp. Pain 2014; 21 (5): 242-253. Available at: scielo.isciii.es