Quadratus lumborum
Musculus quadratus lumborum
MuscularDeep musclesAbdomenLeft and right
View left in 3D View right in 3D
- What it is
- Quadrilateral muscle of the posterior abdominal wall between the iliac crest and iliolumbar ligament below and the 12th rib and transverse processes of L1–L4 above, lateral to psoas and in front of erector spinae.
- Function
- Bends the trunk to its own side, extends the lumbar spine and anchors the 12th rib during deep inspiration.
- Size
- About 12 cm tall, 5–6 cm wide, 1–2 cm thick.
- Clinical note
- A common hidden source of low-back pain; the kidney lies directly in front of it.