The multifidus is a deep muscle of the back. It is located underneath the semispinalis muscle and most developed in the lumbar area.
- Attachments: Has a broad origin – arises from the sacrum, posterior iliac spine, common tendinous origin of the erector spinae, lumbar vertebrae, transverse processes of T1-T3 and articular processes of C4-C7. The fibres ascend 2-4 vertebral segments, attaching to the vertebral spinous processes.
- Actions: Stabilises the vertebral column.
- Innervation: Posterior rami of the spinal nerves
- Blood Supply: Supplied by multiple arteries localised to region along the vertebral column – vertebral, deep cervical, and occipital arteries in the cervical region; dorsal branches of posterior intercostal and subcostal arteries in the thoracic region.