The multifidus is the most important deep stabilising muscle of the spine, spanning 2 to 4 vertebral levels from origin to insertion and providing precise intersegmental stiffness across the entire vertebral column from the sacrum to the cervical spine. Unlike the global mobiliser muscles, it responds primarily to anticipatory neurological activation before limb movements occur, pre-stiffening individual segments to protect them from the forces generated by the moving limb.
| Origin | Sacrum, posterior iliac spine, transverse processes of all lumbar, thoracic, and lower cervical vertebrae |
|---|---|
| Insertion | Spinous processes of vertebrae 2 to 4 levels above the origin |
| Nerve Supply | Posterior rami of spinal nerves at each level |
| Blood Supply | Posterior spinal arteries |
| Actions | Extension of the vertebral column; Rotates the spine contralaterally; Stabilises individual vertebral segments during movement |
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Its short, oblique fibre architecture is optimised for generating extension torque and rotational control at individual vertebral segments rather than producing bulk movement, making it the ideal deep stabiliser that provides fine-grained control where the global movers cannot.
Multifidus atrophy is one of the most consistent MRI findings in patients with chronic low back pain and occurs rapidly after acute disc herniation, often before pain onset, suggesting it may precede rather than follow the pain episode. The lumbar multifidus is the primary target of specific stabilisation exercise programmes for low back pain, and ultrasound-guided assessment of its cross-sectional area is used clinically to monitor its rehabilitation. Recovery of multifidus function does not occur spontaneously after acute low back pain resolves without targeted exercise.
The lumbar multifidus is palpable with deep bilateral finger pressure applied 2 to 3 centimetres lateral to the lumbar spinous processes, feeling for the muscle to contract during active lumbar extension or specific stabilisation contractions.
Rapid loss of multifidus cross-sectional area following acute low back injury or disc herniation, detectable on MRI and associated with chronic low back pain and recurrence risk if not specifically rehabilitated with targeted exercise.
