Muscle
Quadratus lumborum
Posterior abdominal wall
High-yield
Lateral flexor of the trunk; anchors rib 12 for the diaphragm. Supplied by T12-L4 ventral rami.
Overview
A quadrangular muscle of the posterior abdominal wall that laterally flexes the trunk and fixes the 12th rib during respiration.
Reference facts
- Origin
- Iliac crest and iliolumbar ligament
- Insertion
- 12th rib and transverse processes of L1-L4
- Action
- Laterally flexes the vertebral column; fixes the 12th rib in inspiration; extends the lumbar spine bilaterally
- Innervation
- Anterior rami of T12-L4 (subcostal and upper lumbar nerves)
- Blood supply
- Lumbar / subcostal arteries
Frequently asked questions
What does the quadratus lumborum do?
The quadratus lumborum laterally flexes the vertebral column; fixes the 12th rib in inspiration; extends the lumbar spine bilaterally.
What nerve innervates the quadratus lumborum?
The quadratus lumborum is innervated by the anterior rami of T12-L4 (subcostal and upper lumbar nerves).
Where does the quadratus lumborum attach?
The quadratus lumborum originates from the iliac crest and iliolumbar ligament and inserts on the 12th rib and transverse processes of L1-L4.
What is the blood supply of the quadratus lumborum?
The quadratus lumborum is supplied by the lumbar / subcostal arteries.