Lower BackSource-checked

Erector spinae

Erector spinae (iliocostalis, longissimus, spinalis)

Pronunciation: ee-REK-tor SPY-nee

Simplified back view showing the lumbar vertebrae stacked above the sacrum in the midline, the long erector spinae columns running alongside the spine, and the deeper quadratus lumborum between the lowest rib and the pelvis. — Lower back region — lumbar spine, erector spinae, and quadratus lumborum (simplified). A beginner-level schematic of the lower back's bony spine and its two main muscle groups: the erector spinae and quadratus lumborum.
Illustration: Anatomy Learning Platform (original) · CC0-1.0 (public domain dedication)

For beginners

This is the long muscle group you can feel running up either side of your spine. It straightens your back and keeps it from collapsing forward when you bend or lift.

Show the advanced explanation

It is really three parallel columns (iliocostalis, longissimus, spinalis) that together extend and stabilize the spine; during a hip-hinge lift it often works isometrically (holding length) while the hips and knees do most of the moving.

Structure & function

Location: A group of three long muscle columns running up either side of the spine, from the pelvis toward the skull.
Origin: Sacrum, iliac crest, and spinous/transverse processes of the lower vertebrae.
Insertion: Ribs and transverse/spinous processes of vertebrae higher up the spine, and the skull (longissimus capitis).
Main action(s): Extends the vertebral column (straightens the back from a bend); acting on one side, laterally flexes the spine; controls the lowering phase of a forward bend.
Joint(s) crossed: Lumbar and thoracic intervertebral joints
Movement plane: sagittal (extension); frontal (unilateral lateral flexion)
Innervation: Dorsal rami of spinal nerves at each level
In daily movement: Standing upright, straightening up from bending over, and controlling how you lower into a bend.
In exercise: The prime mover in extension-based back exercises (back extensions, deadlifts, good mornings) and a key isometric stabilizer in almost every standing lift.
Commonly confused with: Often blamed as 'the' muscle doing all deadlift work — in a well-coached hip hinge, the glutes and hamstrings drive the movement while the erector spinae mainly stabilizes.
Common misconceptions: 'A strong lower back means a rounded back is safe under load' is false — the erector spinae stabilizes best in a neutral spine, not a flexed one.

Exercises that use this muscle

As a primary mover

As a secondary / stabilizer

Bird-Dog (secondary)

⚠ Safety note

Sharp pain, spasm, or pain radiating into a leg during back extension exercise is a stop signal, not something to push through.

Sources

“The erector spinae group extends and laterally flexes the vertebral column and is a key postural stabilizer.”

Anatomy and Physiology 2e — OpenStax, Rice University · Ch. 11.4 Axial Muscles of the Abdominal Wall, and Thorax and the Deep Back

Peer-reviewed textbook · License: CC BY-NC-SA 4.0 · Last checked 2026-07-19

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