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