Quadratus Lumborum – Anatomy Breakdown
Treadwell, DPT | Muscle by Muscle Series
Watch the Episode
Watch on YouTube: Quadratus Lumborum – Anatomy Breakdown
In this episode, Dr. Austin Treadwell, DPT breaks down the Quadratus Lumborum — a deep stabilizer that doesn’t get the hype it deserves. This muscle quietly controls spinal motion, pelvic symmetry, and load transfer between your upper and lower body.
Overview
The Quadratus Lumborum (QL) sits deep in your lower back, connecting the pelvis to the spine and ribs. It’s a key player in core stability, postural control, and side bending — but it’s also one of the most common sources of one-sided low-back tightness and discomfort.
You’ll find it working in nearly everything — from carrying a heavy bag on one side, to stabilizing during loaded squats and deadlifts. It’s the unsung hero of your trunk’s support system.
Origin & Insertion
Origin: Posterior iliac crest and iliolumbar ligament
Insertion: Inferior border of the 12th rib and transverse processes of L1–L4
𖤓The QL forms part of the posterior abdominal wall, positioned just lateral to the lumbar vertebrae and deep to the erector spinae and latissimus dorsi.
Function
Unilateral: Lateral flexion (side bending) of the trunk; assists in hip hiking
Bilateral: Lumbar extension and stabilization during upright posture
Accessory respiration: Fixes the 12th rib during forced inhalation and exhalation
Biomechanically, the QL acts like a guy-wire for your spine — countering side-to-side shear forces and maintaining balance between the trunk and pelvis
Innervation & Blood Supply
Innervation: Ventral rami of T12–L4
Blood Supply: Lumbar arteries and the iliolumbar artery
Clinical & Training Insights
Tight or overactive QL can lead to uneven pelvic tilt, rib elevation, or referred low-back pain.
Weak or inhibited QL may contribute to instability during single-leg stance or uneven loading patterns in squats and deadlifts.
Activation drills like side planks, suitcase carries, and controlled lateral flexion can restore balance and endurance.
Manual therapy, dry needling, and breathing retraining can relieve chronic QL tension while improving trunk control.
Research Spotlight: Imaging studies have shown increased asymmetry in QL thickness among individuals with chronic low-back pain — suggesting both overuse and compensation patterns rather than simple tightness (Akuthota et al., 2024).
Clinical Relevance
The QL is often mistaken for “low-back tightness,” but it’s really a deep stabilizer reacting to imbalance elsewhere — hip immobility, weak glutes, or poor breathing mechanics. Understanding its role can shift your approach from “stretch it” to “stabilize it.”
Take the Next Step
You’ve got the anatomy down — now put it into motion.
If you’re a clinician, let’s talk application.
If you’re an athlete or lifter, let’s talk performance.
And if you’re working through low-back tightness or asymmetry — this is where anatomy meets action.
𖤓 Watch more breakdowns on YouTube: Treadwell, DPT – Muscle by Muscle Series
𖤓 Book a Virtual Consultation: TreadwellDPT.com/appointments
𖤓 Download free PT tools & anatomy resources: TreadwellDPT.com/resources
Much more in store; even more to come.
Stay tuned, stay locked. Treadwell, DPT. 🚀
