Back Muscles: Origins, Insertions, Actions

Posted on Mar 4, 2025 in Physiotherapy

Trapezius

  • Origin:
    • Superior: Occipital protuberance, C2-C7, nuchal line.
    • Medial: T1-T4.
    • Inferior: T5-T12.
  • Insertion:
    • Superior: Lateral 1/3 of clavicle.
    • Medial: Acromion process.
    • Inferior: Spine of scapula.
  • Action:
    • Superior: Raises shoulders.
    • Medial: Adduction of scapula.
    • Inferior: Stabilization and depression of scapula.
  • Innervation: Accessory nerve and cervical nerves.

Latissimus Dorsi

  • Origin: Iliac crest, sacral crest, spinous processes of L5-T6, and ribs 10-12.
  • Insertion: Inferior angle of scapula and bicipital groove of humerus.
  • Action: Medial rotation, retropulsion, and adduction of humerus.
  • Innervation: Thoracodorsal nerve.

Rhomboids (Minor and Major)

  • Origin:
    • Rhomboid Minor: Nuchal ligament and spinous processes of C7-T1.
    • Rhomboid Major: Spinous processes of T2-T5.
  • Insertion:
    • Rhomboid Minor: Root (medial end) of the spine of the scapula.
    • Rhomboid Major: Medial border of scapula (from inferior angle to the root of the spine of the scapula).
  • Action: Medial rotation, adduction, and elevation of scapula.
  • Innervation: Dorsal scapular nerve.

Levator Scapulae

  • Origin: Transverse processes of C1-C4.
  • Insertion: Medial border of scapula (from superior angle to the root of the spine of the scapula).
  • Action: Medial rotation and elevation of scapula.
  • Innervation: Dorsal scapular nerve.

Serratus Posterior Superior

  • Origin: Nuchal ligament, spinous processes of C7-T3.
  • Insertion: Superior borders of ribs 2-5.
  • Action: Elevates ribs.
  • Innervation: Intercostal nerves.

Serratus Posterior Inferior

  • Origin: Spinous processes of T11-L2.
  • Insertion: Inferior borders of ribs 8-12.
  • Action: Depresses ribs.
  • Innervation: Intercostal nerves.

Splenius Capitis

  • Origin: Spinous processes of C7-T3, nuchal ligament.
  • Insertion: Lateral superior nuchal line of occipital bone, mastoid process of temporal bone.
  • Action: Extends head and neck.
  • Innervation: Posterior rami.

Splenius Cervicis

  • Origin: Spinous processes of T3-T6.
  • Insertion: Transverse processes of C1-C3.
  • Action: Extension of the neck, lateral flexion, and rotation of the neck.
  • Innervation: Posterior rami.

Iliocostalis (3 Fascicles)

  • Origin:
    • Iliocostalis Cervicis: Angle of ribs 3-6.
    • Iliocostalis Thoracis: Angle of ribs 7-12.
    • Iliocostalis Lumborum: Lateral crest of sacrum.
  • Insertion:
    • Iliocostalis Cervicis: Transverse processes of C4-C6.
    • Iliocostalis Thoracis: Angles of ribs 1-6, transverse process of C7.
    • Iliocostalis Lumborum: Angle of ribs 5-12, transverse processes of L1-L4.
  • Action: Extension and lateral flexion of the spine.
  • Innervation: Posterior rami.

Longissimus

  • Origin:
    • Longissimus Capitis: Transverse processes of C4-T5.
    • Longissimus Cervicis: Transverse processes of T1-T5.
    • Longissimus Thoracis: Posterior surface of sacrum and posterior iliac crest.
  • Insertion:
    • Longissimus Capitis: Mastoid process of temporal bone.
    • Longissimus Cervicis: Transverse processes of C2-C6.
    • Longissimus Thoracis: Transverse processes of L1-L5 and T1-T12.
  • Action: Extension and lateral flexion of the spine.
  • Innervation: Posterior rami.

Spinalis (Capitis, Cervicis, and Thoracis)

  • Origin:
    • Spinalis Capitis: Spinous processes of C7-T1.
    • Spinalis Cervicis: Spinous process of C7-T1; nuchal ligament.
    • Spinalis Thoracis: Spinous process of T11-L2.
  • Insertion:
    • Spinalis Capitis: Occipital bone.
    • Spinalis Cervicis: Spinous process of C2-C4.
    • Spinalis Thoracis: Spinous process of T2-T8.
  • Action: Extension of spine and head, lateral flexion of spine and head.
  • Innervation: Posterior rami.

Semispinalis

  • Origin: Articular processes of C4-C7, transverse processes of T1-T6.
  • Insertion: Between superior and inferior nuchal lines of occipital bone.
  • Action: Extension and lateral flexion of the head.
  • Innervation: Spinal nerves.

Multifidus

  • Origin: Sacrum and transverse processes of L5-T12 and their ligaments.
  • Insertion: Spinous processes of L5-Atlas.
  • Action: Extension, lateral flexion, and rotation of the spine.
  • Innervation: Posterior rami.

Rotatores

  • Origin: Transverse processes of thoracic vertebrae.
  • Insertion: Laminae/spinous process of vertebra.
  • Action: Extension and rotation of the thoracic spine.
  • Innervation: Posterior rami.

Intertransversarii

  • Origin: Transverse processes of L1-L4.
  • Insertion: Transverse process of succeeding vertebra.
  • Action: Stabilize the spine and assist with lateral flexion.
  • Innervation: Anterior rami of spinal nerves.

Interspinales

  • Origin:
    • Longissimus Capitis: Spinous process of C3-T1.
    • Longissimus Cervicis: Spinous process of T2-T12.
    • Longissimus Thoracis: Spinous process of L2-L5.
  • Insertion:
    • Longissimus Capitis: Spinous process of C2-C7.
    • Longissimus Cervicis: Spinous process of T1-T11.
    • Longissimus Thoracis: Spinous processes of L1-L4.
  • Action: Extension of cervical and lumbar spine.
  • Innervation: Posterior rami.