ANATOMY – ERECTOR SPINAE & TRANSVERSOSPINALIS MUSCLES

MUSCLES OF THE SPINE

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ERECTOR SPINAE GROUP
(1) Spinalis (2) Longissimus (3) Iliocostalis

TRANSVERSOSPINALIS GROUP
(1) Rotatores (2) Multifidus (3) Semispinalis

ERECTOR SPINAE GROUP

Radiopaedia.org – Intermediate layer of the intrinsic muscles of the back with the group divisions occurring by location.
  1. iliocostalis subgroup is the most lateral
  2. longissimus subgroup is between iliocostalis and spinalis
  3. spinalis subgroup is the most medial
INNERVATION
  • lateral branches of dorsal rami of cervical, thoracic and lumbar spinal nerves
  • at the lumbar levels, lateral branches of the dorsal rami innervate iliocostalis and intermediate branches innervate longissimus
FUNCTION
  • extensors of the back when the thoracic and lumbar components of the erector spinae act bilaterally
  • lateral flexion when the thoracic and lumbar components act unilaterally
  • control of the descent of the thorax towards gravity when the abdominal muscles contract until abdominal muscles are fully flexed – at that point flexion is limited by passive tension from the components of the back.
  • control of the descent of the thorax towards gravity during lateral flexion, aided by the abdominal obliques
  • functions of the cervical and capital erector spinae muscles are not clear

TRANSVERSOSPINALIS MUSCLE GROUP

Radiopaedia.org – Deep layer of the intrinsic back muscles between the transverse and spinous processes and are grouped by length of the fascicles, as well as region covered:
  1. Rotatores
  2. Multifidus
  3. Semispinalis
INNERVATION
  • Rotatores, Multifidus, Semispinalis Thoracis and Cervicis muscles: medial branches of dorsal rami of associated spinal nerves
  • Semispinalis Capitis muscle: descending branch of the greater occipital nerve (C2) and the C3 spinal nerve
FUNCTION
  • all of the Transversospinalis muscles are extensors of the back and neck
  • Rotatores muscles are identified as rotators in many texts, but this action has not been validated and the Rotatores are more likely stabilizers of the spinal column
  • the Multifidus and Semispinalis muscle group has also been identified as rotators by some texts and refuted in others

VIDEOS

  1. Abelson – DC – 18 Muscles of the Spine .
  2. Webster – Erector Spinae Group .
    (1) Iliocostalis (2) Longissimus (3) Spinalis
  3. Webster – Transversospinalis Muscle Group .
    (1) Rotatores (2) Multifidus (3) Semispinalis

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