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Erector spina, thorocal lateral part


Referred pain pattern


Iliocostalis thoracis -
pain pattern - posterior view
Iliocostalis Thoracis pain pattern - front
Iliocostalis Lumborum pain pattern
Longissimus thoracis - pain pattern

Muscles involved

  • Longissimus (medial of the two)
  • Iliocostalis (lateral of the two)

Muscle type

  • Postural
    • Shortens when overactivated


  • Restricted spinal range of motion
  • Difficulty rising from seated position or in climbing stairs
  • Deep steady ache in spine
  • Hypertrophy of one or both sides of the lower back
  • Scoliosis


Short version


Detailed version, medial aspect


Detailed version, lateral aspect

Important functions

  • An important postural muscle (during dysfunction it easily responds by becoming hypertonic)
  • Depresses the lower ribs and is active at the end of inhalation and during maximum exhalation

Notes of clinical importance

  • It has been shown that after injury occurs to the lower back, in some cases the multifidus have lost significant levels of their endurance potential, as well as high level of atrophy which often is accompanied by lower back pain. The atrophy will often remain after the episodic pain period is over, so efforts to regain normal muscle balance is important (1)
  • Patients with both unilateral as well as bilateral radiculopathy show severe and extensive atrophy of the lumbar multifidus muscles which is shown by MRI (2)

Additional information

  • During tests it has been shown that when a subject stand on a wide platform that is abruptly moved backward, the posterior muscles - paraspinal, hamstrings, and gastrocnemius are recruited to bring the body back to the erect position by rotating at the ankles
  • This demonstrates the body's coping mechanism with correcting imbalance by using synergistic muscles



  • Deep


  • Pelvis


  • Spine
  • Ribcage
  • Head

Main function

  • Trunk:
    • Extension
    • Lateral flexion
    • Ipsilateral rotation
  • Pelvis:
    • Anterior tilt

Secondary function

  • Pelvis:
    • Elevation
    • Contralateral rotation

Nerve innervation

  • Spinal nerves
    • Dorsal cervical rami
    • Dorsal thoracic rami
    • Dorsal lumbar rami

Arterial supply

  • Dorsal branches of the posterior intercostals
  • Lumbar arteries
  • Thoracodorsal artery


  1. Hides J, Stoke S, Saide M. Evidence of lumbar multifidus wasting ipsilateral to symptoms in paients with acute/subacute low back pain. Spine 1993; 19: 165-172. PubMed
  2. Min JH, Choi HS, Ihl Rhee W, Lee JI. Association between radiculopathy and lumbar mutlfidius athrophy in magnetic resonance imaging. Journal of Back and Musculoskeletal Rehabilitation 2013; 26: 175-81. doi:10.3233/BMR-130365 DOI