Pronunciation (lon-GIS-I-mus tho-RA-sus) Origin/Proximal Attachment Transverse processes of lumbar vertebrae; intermediate continuation of erector spinae Insertion/Distal Attachment Transverse processes of all thoracic vertebrae; lower 9 or10 ribs between tubercles & angles; transverse processes of upper lumbar vertebrae Action/Relevance Extends & laterally flexes vertebral column; can depress ribs Innervation Thoracic & lumbar nerves | 
