Lumbar innervation and action

Question 1

Multifidus

Answer 1

Innervation: Medial branch of the posterior rami of spinal
nerves
Action: Stabilizes vertebrae in local movements of the
vertebral column
Bilaterally extends the vertebral column
Unilaterally produces contralateral rotation

Question 2

Erector spinae
Longissimus
Thoracic pars lumborum
Iliocostalis lumborum

Answer 2

Innervation: segmental
Action: Primary extensors of vertebral column
Acting bilaterally, they straighten the back–
returning it from an flexed position.