The quadratus lumborum muscle, informally called the ''QL'', is a paired muscle of the left and right
posterior abdominal wall. It is the deepest abdominal muscle, and commonly referred to as a back muscle. Each muscle of the pair is an irregular quadrilateral in shape, hence the name.
The quadratus lumborum muscles originate from the wings of the
ilium; their insertions are on the
transverse processes
Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...
of the upper four lumbar
vertebrae
Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...
plus the lower posterior border of the twelfth rib. Contraction of one of the pair of muscles causes lateral flexion of the
lumbar spine
The lumbar vertebrae are located between the thoracic vertebrae and pelvis. They form the lower part of the back in humans, and the tail end of the back in quadrupeds. In humans, there are five lumbar vertebrae. The term is used to describe t ...
, ''elevation'' of the pelvis, or both. Contraction of both causes ''extension'' of the lumbar spine.
A disorder of the quadratus lumborum muscles is pain due to
muscle fatigue
Muscle fatigue is when muscles that were initially generating a normal amount of force, then experience a declining ability to generate force. It can be a result of vigorous exercise, but abnormal fatigue may be caused by barriers to or interfer ...
from constant contraction due to prolonged sitting, such as at a computer or in a car.
[Core Topics in Pain, p. 131, Anita Holdcraft and Sian Jaggar, 2005.] Kyphosis
Kyphosis () is an abnormally excessive convex curvature of the Spinal column, spine as it occurs in the Thoracic spine, thoracic and sacrum, sacral regions. Abnormal inward concave ''lordotic'' curving of the Cervical spine, cervical and Lumba ...
and weak
gluteal muscles
The gluteal muscles, often called glutes, are a group of three muscles which make up the gluteal region commonly known as the buttocks: the gluteus maximus muscle, gluteus maximus, gluteus medius muscle, gluteus medius and gluteus minimus muscl ...
can also contribute to the likelihood of quadratus lumborum pain.
Structure
The quadratus lumborum muscle originates by
aponeurotic
An aponeurosis (; : aponeuroses) is a flattened tendon by which muscle attaches to bone or fascia. Aponeuroses exhibit an ordered arrangement of collagen fibres, thus attaining high tensile strength in a particular direction while being vulnerabl ...
fibers into the
iliolumbar ligament
The iliolumbar ligament is a strong ligament which attaches medially to the transverse process of the 5th lumbar vertebra, and laterally to back of the inner lip of the iliac crest (upper margin of ilium).
Anatomy
The ligament extends inferola ...
and the internal lip of the
iliac crest
The crest of the ilium (or iliac crest) is the superior border of the wing of ilium and the superolateral margin of the greater pelvis.
Structure
The iliac crest stretches posteriorly from the anterior superior iliac spine (ASIS) to the posterio ...
for about . It inserts from the lower border of the last
rib
In vertebrate anatomy, ribs () are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the thoracic cavity, enabling the lungs to expand and thus facilitate breathing by expanding the ...
for about half its length and by four small tendons from the apices of the
transverse processes
Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...
of the upper four
lumbar vertebrae
The lumbar vertebrae are located between the thoracic vertebrae and pelvis. They form the lower part of the back in humans, and the tail end of the back in quadrupeds. In humans, there are five lumbar vertebrae. The term is used to describe t ...
.
The number of attachments to the vertebræ, and the extent of its attachment to the last rib, may vary. Also, occasionally, a second portion of this muscle is found in front of the preceding. It arises from the upper borders of the transverse processes of the lower three or four
lumbar vertebræ, and is inserted into the lower margin of the last rib.
Relationships
File:Gray388.png, Cross-section of the posterior abdominal wall, showing on the right the relationship of the quadratus lumborum muscle to the psoas major
The psoas major ( or ; from ) is a long fusiform muscle located in the lateral lumbar region between the vertebral column and the brim of the lesser pelvis. It joins the iliacus muscle to form the iliopsoas. In other animals, this muscle is e ...
and sacrospinalis
The erector spinae ( ) or spinal erectors is a set of muscles that straighten and rotate the back. The spinal erectors work together with the glutes (gluteus maximus, gluteus medius and gluteus minimus) to maintain stable posture standing or si ...
muscles.
Gray1124.png, Posterior view showing on the left the relationship of the left kidney
In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...
to the left quadratus lumborum muscle.
Anterior to the quadratus lumborum are the
colon, the
kidney
In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...
, the psoas major muscle, (if present) the
psoas minor
The psoas minor muscle ( or ; from ) is a long, slender skeletal muscle. When present, it is located anterior to the psoas major muscle.Tank (2005), p 93Gray (2008), p 1372
Structure
The psoas minor muscle originates from the vertical fascicles ...
muscle, and the
diaphragm; between the fascia and the muscle are the twelfth thoracic,
ilioinguinal, and
iliohypogastric nerves. The quadratus lumborum muscle is a continuation of
transverse abdominal muscle
The transverse abdominal muscle (TVA), also known as the transverse abdominis, transversalis muscle and transversus abdominis muscle, is a muscle layer of the anterior and lateral (front and side) abdominal wall, deep to (layered below) the inter ...
.
Nerve supply
Anterior branches of the ventral rami of T12 to L4.
Functions
The quadratus lumborum can perform four actions:
# Lateral flexion of vertebral column, with
ipsilateral
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
contraction
# Extension of lumbar vertebral column, with bilateral contraction (based on line of force passing ~3.5 cm posterior L3 rotation axis
[McGill SM, Santaguida L, Stevens J: Measurement of the trunk musculature from T5 to L5 using MRI scans of 15 young males corrected for muscle fibre orientation, Clin Biomech (Bristol, Avon) 8:171-178, 1993.])
# Fixes the 12th rib during forced expiration. The quadratus lumborum assists the diaphragm in inhalation
# Elevates the
Ilium (bone)
The ilium () (: ilia) is the uppermost and largest region of the coxal bone, and appears in most vertebrates including mammals and birds, but not bony fish. All reptiles have an ilium except snakes, with the exception of some snake species ...
, with
ipsilateral
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
contraction ("hip hiking")
Additional functions:
* Vertical stabilization of pelvis, lumbar spine, and lumbosacral junction. Prevents collapse of the vertebral column in the frontal plane (i.e. scoliosis)
* Reserve mover actions: anterior pelvic tilt.
* Contralateral lateral pelvic rotation.
Clinical significance
The quadratus lumborum muscles can be the source of back pain when overused, or in association with scoliosis or weak gluteal muscles.
Mechanism
The quadratus lumborum is a common source of unilateral or bilateral lower back pain, including localized pain and tenderness over the wing of the ilium.
[''Clinical Orthopaedic Examination'', Ronald McRae, 2004 (5th ed.).] Because quadratus lumborum connects the
pelvis
The pelvis (: pelves or pelvises) is the lower part of an Anatomy, anatomical Trunk (anatomy), trunk, between the human abdomen, abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also c ...
to the
spine
Spine or spinal may refer to:
Science Biology
* Spinal column, also known as the backbone
* Dendritic spine, a small membranous protrusion from a neuron's dendrite
* Thorns, spines, and prickles, needle-like structures in plants
* Spine (zoology), ...
and is therefore capable of extending the lower back when contracting bilaterally, the two quadratus lumborum muscles pick up the slack, as it were, when the lower fibers of the
erector spinae
The erector spinae ( ) or spinal erectors is a set of muscles that straighten and rotate the back. The spinal erectors work together with the glutes (gluteus maximus, gluteus medius and gluteus minimus) to maintain stable posture standing or si ...
are weak or inhibited (as they often are in the case of habitual seated computer use and/or the use of a lower back support in a chair). Given their comparable mechanical disadvantage, constant contraction while seated can overuse the quadratus lumborum, resulting in
muscle fatigue
Muscle fatigue is when muscles that were initially generating a normal amount of force, then experience a declining ability to generate force. It can be a result of vigorous exercise, but abnormal fatigue may be caused by barriers to or interfer ...
.
[Core Topics in Pain, p. 131, Anita Holdcraft and Sian Jaggar, 2005.] A constantly contracted quadratus lumborum, like any other muscle, will experience decreased blood flow, and, in time, adhesions in the muscle and
fascia
A fascia (; : fasciae or fascias; adjective fascial; ) is a generic term for macroscopic membranous bodily structures. Fasciae are classified as superficial, visceral or deep, and further designated according to their anatomical location.
...
may develop, the end point of which is
muscle spasm
A spasm is a sudden involuntary contraction of a muscle, a group of muscles, or a hollow organ, such as the bladder.
A spasmodic muscle contraction may be caused by many medical conditions, including dystonia. Most commonly, it is a musc ...
.
Association with kyphosis
This chain of events can be and often is accelerated by
kyphosis
Kyphosis () is an abnormally excessive convex curvature of the Spinal column, spine as it occurs in the Thoracic spine, thoracic and sacrum, sacral regions. Abnormal inward concave ''lordotic'' curving of the Cervical spine, cervical and Lumba ...
, 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
The multifidus (multifidus spinae; : ''multifidi'') muscle consists of a number of fleshy and tendinous fasciculi, which fill up the groove on either side of the spinous processes of the vertebrae, from the sacrum to the axis. While very thin, t ...
, and especially the
levator scapulae to work harder in both seated and standing positions to maintain an erect torso and neck. The experience of "productive pain" or pleasure by a patient upon
palpation
Palpation is the process of using one's hands to check the body, especially while perceiving/diagnosing a disease or illness. Usually performed by a health care practitioner, it is the process of feeling an object in or on the body to determine ...
of the quadratus lumborum is indicative of such a condition.
Association with weak gluteal muscles
Hip abduction is performed primarily by the hip abductors (gluteus medius and minimus). When the gluteus medius/minimus are weak or inhibited, the tensor fasciae latae or quadratus lumborum will compensate by becoming the prime mover. The most impaired movement pattern of hip abduction is when the quadratus lumborum initiates the movement, which results in hip hiking during swing phase of gait. Hip hiking places excessive side-bending compressive stresses on the lumbar segments. Thus, a tight quadratus lumborum may be another hidden cause of low back pain (Janda 1987).
When the hip adductors are tight or hypertonic, their antagonist (gluteus medius) may experience reciprocal inhibition. The gluteus medius will become weak and inhibited. This in turn may cause hypertonicity of ipsilateral quadratus lumborum. Chronic hypertonicity of quadratus lumborum tends to cause low back pain due to its ability to create compressive stress on lumbar segment.
Treatment
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.
Current studies show that application of heat or ice, massage, and estim will not leave long-term benefits. Careful assessment of muscular imbalances and movement impairments by a therapist is recommended in order to address the underlying issues mentioned.
[''Assessment and Treatment of Muscle Imbalances'', p. 100, Phil Page, 2010.]
References
External links
* - "Posterior Abdominal Wall, Dissection, Anterior View"
{{Authority control
Muscles of the torso