Multifidus Muscle

Description

Running deep to the erector spinae, the multifidus forms paired, segmental bundles along the posterior vertebral column in an adult male, spanning from the sacrum and posterior superior iliac spine region to the cervical vertebrae. Fibers arise from the dorsal surface of the sacrum, mammillary processes in the lumbar spine, transverse processes in the thoracic region, and articular processes in the cervical region, then course superomedially to insert on adjacent spinous processes one to four levels above. Medially, the muscle hugs the spinous processes and interspinous ligaments; laterally, it is overlapped by the erector spinae mass. Portions of the posterior ribs and the pelvic ring anchor the scene inferiorly. Clinically, this view matters because the multifidus is the primary local stabilizer of each motion segment, controlling shear and rotation across the facet (zygapophysial) joints while the more superficial erector spinae drives gross extension. That distinction becomes obvious in lumbar instability, spondylolysis, and chronic low back pain, where MRI commonly shows multifidus fatty infiltration and atrophy, often persisting after discectomy or lumbar fusion and correlating with recurrent symptoms. Small and deep. It is also the key muscle targeted in motor-control rehab and is vulnerable during midline posterior approaches where detachment from the spinous processes can denervate segmental fibers via the medial branches of the dorsal rami. Use this plate for teaching spinal extensor layering in gross anatomy and kinesiology, for illustrating posterior surgical corridors and muscle-sparing techniques in orthopedic or neurosurgical texts, or for patient education around facet-mediated pain procedures and post-op rehabilitation planning. Anatomical accuracy verified by SciePro's Medical Advisory Board.