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origin: superior borders of the angles of lower 6 ribs medial to the tendons of insertion of the  Iliocostalis Lumborum;
insertion: into the angles of the upper 6 or 7 ribs and into the transverse process of the 7th cervical vertebrae;
action: acting bilaterally, extension and hyperextension of the spine; acting unilaterally, laterally flexes the spine;
nerve supply: posterior rami of the spinal nerves;
synergists: Iliocostalis Lumborum, Longissimus Thoracis, Spinalis Thoracis, Semispinalis Thoracis