QUADRATUS
LUMBORUM
• Origin
Posterior iliac crest
Iliolumbar ligament
• Insertion
Inferior border of 12th rib
Transverse processes of L1–L4 vertebrae
• Agonist(s)
- Iliocostalis lumborum (in lateral flexion and spinal extension),
- Longissimus thoracis (in spinal extension),
- Psoas major (in pelvic stabilization and hip hiking).
• Antagonist(s)
- External obliques (contralateral side during lateral flexion),
- Internal obliques (contralateral side during lateral flexion),
- Rectus abdominis (during spinal flexion).
• Function
Laterally flexes the lumbar spine (unilateral contraction).
Extends the lumbar spine (bilateral contraction).
Fixes the 12th rib during forced inspiration.
Assists in pelvic elevation (“hip hiking”).
Stabilizes the lumbar spine during movement.
TRIGGER POINT(S)
• Location
Commonly located along the lateral edge of the lumbar vertebrae, deep to the erector spinae.
TrPs often found near the iliac crest and lower 12th rib region.
Can be difficult to palpate directly due to depth and overlying musculature.
• Pain Referral Pattern
Deep aching pain in the lower back, often on one side.
Pain may refer to the sacroiliac joint, iliac crest, and lower buttock.
Occasionally refers to the lateral hip and greater trochanter.
Can mimic symptoms of discogenic or sacroiliac dysfunction.
Pain Pattern
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Potential Causes
• Prolonged standing or walking on uneven surfaces.
• Lifting and twisting with improper technique.
• Sitting in unsupported positions, especially asymmetrically.
• Leg length discrepancies or pelvic imbalances.
• Repetitive lateral bending or overuse during sports and physical labor.
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Prevention Tips
• Strengthen core and pelvic stabilizers to reduce compensatory overuse.
• Practice symmetrical posture when sitting or standing.
• Avoid carrying heavy loads on one side of the body.
• Stretch the QL and adjacent lumbar muscles regularly.
• Address structural imbalances (e.g., leg length difference, pelvic tilt) through corrective exercises or manual therapy.
