Pronunciation (mul-TI-fe-dus) Origin/Proximal Attachment Cervical: articular processes of lower cervical vertebrae Thoracic: transverse processes of all thoracic vertebrae Lumbar: mamillary processes of all lumbar vertebrae; tendinous origin of erector spinae; lower portion of back of sacrum; PSIS Insertion/Distal Attachment Onto spinous processes of higher vertebrae - spanning 2-4 vertebrae Action/Relevance Bilaterally: extends vertebral columnUnilaterally: lateral flexion & rotation to opposite side Innervation Segmental supply by dorsal rami of cervical, thoracic & lumbar spinal nerves | 
