Multifidus is a group of short, triangular muscles that along with the semispinalis and rotatores comprises the transversospinal group of deep back muscles. They are the thickest muscles in the transversospinal group, and are shorter than semispinalis, but longer than rotatores. Multifidus is found on either side of vertebral column, extending from the cervical all the way to the lumbar spine. The group is regionally divided into cervical multifidus, thoracic multifidus and lumbar multifidus.
Each multifidus muscle bridges over three to six vertebral levels, spanning between the transverse and spinous processes of certain cervical, thoracic and lumbar vertebrae. Although small, multifidus muscles aid several movements of vertebral column; when contracting bilaterally they extend the spine, while unilateral contraction aids lateral flexion of the spine to the same side and rotation of the spine to the opposite side.
Multifidus cervicis: Superior articular processes of vertebrae C4-C7
Multifidus thoracis: Transverse process of thoracic vertebra
Multifidus lumborum: Mammillary processes of lumbar vertebrae, posterior aspect of sacrum, posterior superior iliac spine (PSIS) of ilium and posterior sacroiliac ligament
|Lateral aspect and tips of the spinous processes of vertebrae 2-5 levels above origin
Bilateral contraction: Extension of spine
Unilateral contraction: Lateral flexion of spine (ipsilateral), rotation of spine (contralateral)
|Medial branches of posterior rami of spinal nerves
|Vertebral artery, deep cervical artery, occipital artery, posterior intercostal arteries, subcostal artery, lumbar ateries and lateral sacral arteries
This article will outline the anatomy and function of multifidus muscle.
Origin and insertion
Cervical multifidus muscles arise from the superior articular processes of C4 – C7. They extend superomedially to insert on the lateral aspect and the tips of the spinous processes of C2 – C5 vertebrae. Thoracic multifidus originate from the transverse processes of the thoracic vertebrae. The fibers also take a superomedial course to insert variably on the spinous processes of the vertebrae 2 – 5 levels above their origin.
Fibers of lumbar multifidus arise from the mammillary processes of lumbar vertebrae and the posterior surface of sacrum. In addition, some fibers also arise from the posterior superior iliac spine of ilium and the posterior sacroiliac ligament. They travel superiorly to insert on the lateral surface and apices of spinous processes 2 to 5 levels above their origin.
As part of the transversospinal muscle group, multifidus is located in the third or deep layer of deep muscles of the back. It lies deep to erector spinae, semispinalis cervicis and thoracis, while it is located superficial to rotatores muscles.
Running through the groove between the spinous and transverse processes of vertebrae, multifidus overlies the laminae of cervical and thoracic vertebrae and the posterior surface of sacrum.
Multifidus is innervated by the medial branches of posterior rami of spinal nerves in the corresponding cervical, thoracic and lumbar regions.
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Multifidus receives arterial blood supply from a number of arteries along the length of the vertebral column. These are as follows:
- Cervical region: vertebral, deep cervical and occipital arteries
- Thoracic region: dorsal branches of posterior intercostal and subcostal arteries
- Lumbar region: lumbar and lateral sacral arteries
Except for the occipital artery, which is a branch of the external carotid artery, the source of the arteries that supply cervical multifidus is subclavian artery. The arteries in the thoracic and lumbar regions are direct branches of the aorta.
For even more anatomy about the deep muscles of the back, including the multifidus, check out the videos, illustrations and quizzes included below:
Bilateral contraction of multifidus produces extension of the vertebral column at all levels. When the muscles contract unilaterally, they produce ipsilateral lateral flexion and contralateral rotation of the vertebral column. Adapting their length to stabilize the vertebrae, multifidus muscle function as extensible ligaments that stabilize the vertebral column.
Don't forget to quiz yourself on the multifidus and other deep muscles of the back to consolidate your knowledge!
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