The Multifidus: Small Muscle, Large Role in Lumbar Control

A Small, Deep, Easily Overlooked Muscle

The multifidus is a series of small, deep muscles running close to the spine itself, segment by segment, from the sacrum to the neck. Despite its modest size relative to larger, more superficial back muscles, it provides a disproportionately important contribution to fine, segment-by-segment control of the lumbar spine.

Why Segmental Control Matters

Because the multifidus attaches directly between adjacent vertebrae, it is uniquely positioned to resist small, segment-specific shear and rotational forces that larger, more superficial muscles are too far from the spine to control effectively — functioning less like a prime mover and more like a stabilising guy-wire for each individual spinal segment.

A Muscle That Changes Quickly After Injury

Research using real-time ultrasound and EMG found that even a single episode of acute low back pain is associated with rapid, measurable inhibition and subsequent atrophy of the multifidus at the painful segment — a change that, without specific retraining, can persist well beyond the resolution of the initial pain episode (Hodges & Richardson, 1996; Freeman et al., 2010). This is a major reason targeted multifidus retraining, rather than simply "core strengthening" in general, is specifically emphasised in evidence-based low back pain rehabilitation.