Origin
Sacrum, and transverse processes of vertebrae.
Insertion
Spinous processes 2-4 vertebrae superior to origin.
Joint crossed
Intervertebral joints of vertebral column.
Joint action
Extension of vertebral column (bilaterally)
Assists in rotation of vertebral column (unilaterally)
Assists in lateral flexion of spine (unilaterally)
Important to lumbar spine stability because it is a ‘local’ muscle, controlling the fine positioning of adjacent vertebrae.
