Quadratus lumborum muscle
Encyclopedia
The Quadratus lumborum is irregular and quadrilateral in shape, and broader below than above.
for about 5 cm., and is inserted into the lower border of the last rib
for about half its length, and by four small tendons into the apices of the transverse processes of the upper four lumbar vertebrae
.
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.
, the kidney
, the Psoas major and (if present) psoas minor, and the diaphragm; between the fascia and the muscle are the twelfth thoracic, ilioinguinal, and iliohypogastric nerves.
to the spine
and is therefore capable of extending the lower back when contracting bilaterally, the two QLs pick up the slack, as it were, when the lower fibers of the erector spinae
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 QLs, resulting in muscle fatigue
. A constantly contracted QL, like any other muscle, will experience decreased bloodflow, and, in time, adhesions in the muscle and fascia
may develop, the end point of which is muscle spasm.
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 QLs by shifting body weight forward, forcing the erector spinae, QLs, multifidi, 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
of the QL is indicative of such a condition.
While stretching and strengthening the QL are indicated for unilateral lower back pain, heat/ice applications as well as massage and other myofascial therapies should be considered as part of any comprehensive rehabilitation regimen.
Origin and insertion
It arises by aponeurotic fibers from the iliolumbar ligament and the adjacent portion of the iliac crestIliac crest
-External links: - "Superficial muscles of the gluteal region and posterior thigh." - "Anterior Abdominal Wall: Osteology and Surface Anatomy " - "The Back, Posterior View" * *...
for about 5 cm., and is inserted into the lower border of the last rib
Rib
In vertebrate anatomy, ribs are the long curved bones which form the rib cage. In most vertebrates, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the chest cavity. They serve to protect the lungs, heart, and other internal organs of the thorax...
for about half its length, and by four small tendons into the apices of the transverse processes of the upper four lumbar vertebrae
Lumbar vertebrae
The lumbar vertebrae are the largest segments of the movable part of the vertebral column, and are characterized by the absence of the foramen transversarium within the transverse process, and by the absence of facets on the sides of the body...
.
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.
Relations
Anterior to the Quadratus lumborum are the colonColon (anatomy)
The colon is the last part of the digestive system in most vertebrates; it extracts water and salt from solid wastes before they are eliminated from the body, and is the site in which flora-aided fermentation of unabsorbed material occurs. Unlike the small intestine, the colon does not play a...
, the kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
, the Psoas major and (if present) psoas minor, and the diaphragm; between the fascia and the muscle are the twelfth thoracic, ilioinguinal, and iliohypogastric nerves.
Variations
The number of attachments to the vertebræ and the extent of its attachment to the last rib vary.Actions
The quadratus lumborum can perform four actions:- Lateral flexion of vertebral column, with ipsilateral contractionMuscle contractionMuscle fiber generates tension through the action of actin and myosin cross-bridge cycling. While under tension, the muscle may lengthen, shorten, or remain the same...
- Extension of lumbar vertebral column, with bilateral contraction
- Fixes the 12th rib during forced expiration
- Levates ilium, with ipsilateral contractionMuscle contractionMuscle fiber generates tension through the action of actin and myosin cross-bridge cycling. While under tension, the muscle may lengthen, shorten, or remain the same...
Indications
The quadratus lumborum, or QL, is a common source of lower back pain. Because the QL connects the pelvisPelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
to the spine
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
and is therefore capable of extending the lower back when contracting bilaterally, the two QLs pick up the slack, as it were, when the lower fibers of the erector spinae
Erector spinae
The Erector spinæ is a muscle group of the back in humans and animals. It is also known as sacrospinalis in older texts. A more modern term is extensor spinae, though this is not in widespread use. The name of the muscle is pronounced e-rec-tor speen-aye, or e-rec-tor spinae-ee.It is really not...
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 QLs, resulting in muscle fatigue
Muscle fatigue
Muscle fatigue is the decline in ability of a muscle to generate force. It can be a result of vigorous exercise but abnormal fatigue may be caused by barriers to or interference with the different stages of muscle contraction...
. A constantly contracted QL, like any other muscle, will experience decreased bloodflow, and, in time, adhesions in the muscle and fascia
Fascia
A fascia is a layer of fibrous tissue that permeates the human body. A fascia is a connective tissue that surrounds muscles, groups of muscles, blood vessels, and nerves, binding those structures together in much the same manner as plastic wrap can be used to hold the contents of sandwiches...
may develop, the end point of which is muscle spasm.
This chain of events can be and often is accelerated by kyphosis
Kyphosis
Kyphosis , also called roundback or Kelso's hunchback, is a condition of over-curvature of the thoracic vertebrae...
which is invariably accompanied by rounded shoulders, both of which place greater stress on the QLs by shifting body weight forward, forcing the erector spinae, QLs, multifidi, 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
Palpation is used as part of a physical examination in which an object is felt to determine its size, shape, firmness, or location...
of the QL is indicative of such a condition.
While stretching and strengthening the QL are indicated for unilateral lower back pain, heat/ice applications as well as massage and other myofascial therapies should be considered as part of any comprehensive rehabilitation regimen.