Multifidus

  • The multifidus (Latin: musculus multifidus spinae) muscle group consists of short and triangular muscles that, along with the semispinalis and rotatores, comprise the transversospinalis group of the deep back muscles. They are shorter than the semispinalis and longer than the rotatores, and the thickest of the three. 

    The multifidus muscles are found on each side of the vertebral column, extending from the cervical part to the lumbar portion of the spine. The multifidus muscles are divided into three portions based on the regions that they occupy. These parts are named the cervical multifidusthoracic multifidus, and lumbar multifidus.

    Each multifidus muscle extends between transverse and spinous processes of vertebrae, bridging over three to six vertebral levels. The contractions of the multifidus have a role in several movements of the spine, including extension, lateral flexion, and rotation of the cervical, thoracic, and lumbar portions of the spine.

     

    Cervical multifidus

    Origin

    The cervical multifidus muscles originate from the superior articular processes of the fourth to seventh cervical vertebrae (C4 - C7).

    Insertion

    The fibers of the cervical multifidus extend superomedially and insert into the spinous processes of the second to fifth cervical vertebrae (C2 - C5).

    Action

    When contracted bilaterally, the cervical multifidus aids in extending the cervical spine, while unilateral contraction aids in lateral flexion (ipsilateral) and rotation of the cervical spine (contralateral).

    Innervation

    The multifidus muscles are innervated by the medial branches of the posterior rami of the spinal nerves.

    Blood supply

    The multifidus muscles that are located in the cervical region receive arterial blood supply mainly via the vertebral and deep cervical arteries, which arise from the subclavian artery, and the occipital arteries - a branch of the external carotid.

     

    Thoracic multifidus

    Origin

    The thoracic multifidus muscles arise from the transverse processes of the thoracic vertebrae.

    Insertion

    The muscle fibers of the thoracic multifidus extend superomedially and insert variably into the spinous processes of the vertebrae 2 to 5 levels above their origin.

    Action

    When contracted bilaterally, the thoracic multifidus aids in the extension of the thoracic spine, while unilateral contraction participates in lateral flexion (ipsilateral) and rotation of the thoracic spine (contralateral).

    Innervation

    The multifidus muscles are innervated by the medial branches of the posterior rami of the spinal nerves.

    Blood supply

    The thoracic multifidus muscles are mainly supplied by the dorsal branches of the posterior intercostal and subcostal arteries, which themselves are direct branches of the descending thoracic aorta.

     

    Lumbar multifidus

    Origin

    The lumbar multifidus muscles originate from the transverse processes of the lumbar vertebrae and the posterior surface of the sacrum. Additionally, some fibers also arise from the posterior superior iliac spine of the ilium and the posterior sacroiliac ligament. 

    Insertion

    The fibers of the lumbar multifidus extend superiorly and insert into the spinous processes of the vertebrae that are 2 to 5 levels above the origin sites.

    Action

    When contracted bilaterally, the thoracic multifidus aids in the extension of the thoracic spine, while unilateral contraction participates in lateral flexion (ipsilateral) and rotation of the thoracic spine (contralateral).

    Innervation

    The multifidus muscles are innervated by the medial branches of the posterior rami of the spinal nerves.

    Blood supply

    The lumbar multifidus muscles are mainly supplied by the lumbar and lateral sacral arteries - direct branches of the abdominal aorta.