The multifidus is the most important lumbar spinal stabiliser, providing segmental control through its short multi-segment architecture. Unlike the erector spinae (gross movers), the multifidus provides fine intersegmental stiffness. It is preferentially atrophied in chronic LBP (visible as fat infiltration on MRI at the painful level) and is the primary target of lumbar stabilisation exercise and specific multifidus rehabilitation.
| Origin | Sacrum, iliac crest, lumbar mamillary processes, thoracic transverse processes, and cervical articular processes — spans two to four vertebral levels at each segment |
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| Insertion | Spinous process of a vertebra two to four levels superior to its origin |
| Nerve Supply | Medial branches of dorsal rami at each level (segmental supply) |
| Blood Supply | Dorsal branches of lumbar and intercostal arteries |
| Actions | Segmental spinal extension and rotation control; The primary intersegmental stabiliser — provides stiffness to each motion segment independent of gross movement; Prevents excessive shear and rotation between adjacent vertebrae |
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Multifidus atrophy at the level of disc herniation or spondylolisthesis is visible on T1 MRI as increased fat signal replacing muscle fibres. The atrophy is level-specific and ipsilateral in disc herniation — it does not recover spontaneously with pain resolution, requiring specific exercise. Transversus abdominis and multifidus co-activation (the 'abdominal hollowing' pattern) is the foundation of lumbar stabilisation programmes.
The multifidus is palpable 2-3 cm lateral to the lumbar spinous processes as the deep muscular column, becoming firm during lumbar extension from the prone position.
Level-specific multifidus fat infiltration from nerve root compression or disuse requiring specific motor control exercise to restore segmental stability.
