Multifidus

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.