- origin and insertion: pairs of small muscles joining the spinous process of adjacent vertebrae, one on each side of the interspinalis ligament; continuous in the cervical region extending from the axis to the 2nd thoracic vertebrae and in the lumbar region from the first lumbar vertebrae to the sacrum;
- action: extension and hyperextension of the spine;
- nerve supply: posterior rami of the spinal nerve;
- synergists: multifidi, rotators, Intertransversarii groups
