- a series of pairs of small muscles extending from the sacrum to the axis;
- origin: transverse processes of the vertebrae;
- insertion: bases of the spinous processes of the 1st vertebrae above;
- action: acting bilaterally, rotation of the spine to the opposite side; acting unilaterally, extension and hyperextension of the spine;
- nerve supply: posterior rami of the spinal nerves;
- synergists: Intertransversarii, Interspinales, Multifidus and Rotators Longus