Anatomy

Origin

Sacral region: along sacral foramina up to posterior superior iliac spine Lumbar region: mammillary processes (posterior border of superior articular process) of vertebrae Thoracic region: transverse processes Cervical region: articular processes of lower four vertebrae (C4–C7)

Insertion

Spinous process two to four vertebrae superior to origin

Nerve

Dorsal primary division of spinal nerves

Actions

Extend and rotate vertebral column