
Quadratus Lumborum Muscle
Origin: Inferior border of the 12th rib
Insertion: Transverse processes of L1 to L4, the iliolumbar ligament, and the posterior third of the iliac crest
Actions: Lateral flexion of the lumbar spine
Innervation: Ventral primary rami of T12 to L3
Blood Supply: Branches from the lumbar artery
Primary Actions of the Quadratus Lumborum
1. Lateral rotation of the lumbar spine when acting unilaterally
Agonists:
- Iliocostalis lumborum
- Longissimus thoracis
- Psoas major
- External oblique
- Internal oblique
Antagonists: Same muscles on contralateral side
- Iliocostalis lumborum
- Longissimus thoracis
- Psoas major
- External oblique
- Internal oblique
The intertransversarii assist with lateral flexion of the lumbar spine
Advertisement
Advertisement
Secondary Actions of the Quadratus Lumborum
1. Elevation of the pelvis when acting unilaterally
Agonists:
- Rectus abdominis
- Internal oblique
- External oblique
Antagonists: None
Muscle Pain Information: The quadratus lumborum muscle contributes to pain in the low back, buttock, hip, and groin.