Name Iliocostalis thoracisPronunciation il-e-o-kos-TA-lus tho-RA-sus Origin/Proximal Attachment Upper border of ribs 6-12(medial to lumborum’s insertion) Insertion/Distal Attachment Lower border of angles of ribs1-6 (sometimes transverse process of C7) Action/Relevance Extends, laterally flexes & assists in rotation of thoracic vertebrae Innervation C8 & T1-6 nerves | 
