Origin: the spinous process of the 1st and 2nd lumbar vertebrae, the thoracic vertebrae 10, 11, 12;
insertion: the spinous process of the thoracic vertebrae 3-8 and sometimes 9;
action: acting unilaterally, lateral flexion of the spine; acting bilaterally, extension and hyperextension of the spine;
nerve supply: posterior rami of the spinal nerves;
synergists: Semispinalis Thoracis, Longissimus Thoracis, iliocostalis thoracis, Iliocostalis Lumborum , longissimus thoracis,
Quadratus Lumborum