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Anatomy of The Lumbar Back Muscles-Multifidus

The multifidus is the most medial and largest of the paraspinal muscles. It has an origin and insertion of vertebra to vertebra attachments within the lumbar spine and between the lumbar and sacral vertebrae .

The multifidus is composed of repeating fascicles, which originate from the laminae and spinous processes of the lumbar vertebrae and insert in a caudal direction. The shortest (deepest) fascicles (laminar fibers) of the multifidus arise from the vertebral laminae and insert on the mamillary process of the vertebrae two levels caudal. The L5 fibers insert on an area of the sacrum just above the first dorsal sacral foramen . “The other fascicles arise from the spinous process and are longer than the laminar fibers.

Each lumbar vertebra gives rise to one group of fascicles which overlap those of the other levels. The fascicles from a given spinous process insert onto mamillary processes of the lumbar and sacral vertebrae three, four, or five levels inferiorly. The longest fascicles, from L1, L2, and L3, have some attachment to the posterior superior iliac spine”.

The fascicles in each group diverge caudally to assume separate attachments to mamillary processes, the iliac crest, and the sacrum. Some of the deeper fibers of these fascicles attach to the capsules of the zygapophyseal joints next to the mamillary process. “The attachment of the muscles of the thoracolumbar fascia represents a raphe separating the multifidus from the gluteus maximus muscle”.

Moseley et al. It reported that the deep and superficial fibers of multifidus are “differentially active from single and repetitive movements of the arm.” They concluded that the “superficial multifidus contributes to the control of spine orientation, and that the deep multifidus has a role in controlling intersegmental motion”. Biomechanical research by Wilke et al. It found that multifidus acts to increase lumbar segmental stability by increasing the stiffness in the motion segment. Multifidus works in co-contraction with the transversus abdominus to control the neutral zone.

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