Erector spinae muscles
Three columns of muscle running the length of the back — the group that holds you upright.
- Type
- Muscle
- Region
- Spine
- Standard name
- musculus erector spinae
- Origin
- A broad common tendon from the sacrum, iliac crest and lumbar spinous processes
- Insertion
- Ribs, transverse and spinous processes of vertebrae, and the skull, in overlapping columns
- Actions
- spine extensiontrunk sidebendingspinal stabilisation
- Verify
- TA2 2254 TA98 A04.3.02.002
What it is
Not one muscle but a group of three parallel columns running either side of the spine from the pelvis to the skull, arising from a broad common tendon over the sacrum and lower back.
From the outside inward:
- Iliocostalis — the outermost, attaching to the ribs
- Longissimus — the middle and longest, reaching as far as the skull
- Spinalis — the innermost and smallest, attaching to spinous processes
Each column is further divided by region, so a full anatomical listing runs to nine named parts. That level of subdivision is descriptive; the columns behave as a group.
The visible ridges either side of the spine in a lean back are these muscles under the thoracolumbar fascia.
What it does
Extends the spine — straightens it, and pulls it backwards past straight. Acting on one side, side-bends the trunk.
Its more important job is what it does while you are not moving: it controls the trunk bending forward. Lean forward and these muscles pay the movement out under tension rather than letting you fall. Everything you do bent over — gardening, lifting, washing up — is this group working continuously against gravity.
They also stiffen the spine segment by segment during loaded movement.
What loads it
Hinging at the hips under load, carrying, holding a braced trunk position, and any bent-over work.
The Repertoire contains no hinge yet, which is the most conspicuous gap in the collection.
What is commonly got wrong about it
"Lower back" as one muscle. It is three columns, nine named parts, sitting over the deeper multifidus and rotatores.
That a rounded back under load is always dangerous. This is one of the most confidently repeated claims in fitness and it is much less settled than it sounds. Spinal flexion under load is a normal movement; the relationship between lifting technique and back injury is genuinely contested, and the evidence that a neutral spine prevents injury is weaker than the emphasis placed on it. What is well supported is that unaccustomed load causes problems and gradual exposure does not.
That back pain means damage. Disc degeneration is present on imaging in 37% of pain-free 20-year-olds and 96% of pain-free 80-year-olds; bulges in 30% and 84%.1 Back pain is common, usually not explained by a single structure, and specifically outside what this site addresses.
That the erectors are a "core" muscle to be isolated. They work with everything else.
Sources
- Brinjikji W, Luetmer PH, Comstock B, et al. Systematic literature review of imaging features of spinal degeneration in asymptomatic populations. American Journal of Neuroradiology 2015; 36(4):811–816. doi:10.3174/ajnr.A4173 PMID 25430861 33 studies, 3,110 people with no symptoms. Disc degeneration present in 37% of 20-year-olds rising to 96% of 80-year-olds; disc bulge 30% to 84%; protrusion 29% to 43%. The authors conclude many such findings are likely part of normal ageing and unassociated with pain.
Every source here was checked against PubMed rather than recalled. Where this site says something is disputed or unsupported and no source appears, that is deliberate: it means the claim is being conceded rather than cited.