Multifidus Lumborum
Back · Trunk
The lumbar multifidus is the deep, well-developed lumbar portion of the multifidus, a member of the transversospinales that lies just superficial to the rotatores. It arises from the posterior surface of the sacrum, the posterior superior iliac spine, and the mammillary processes of the lumbar vertebrae, and each fascicle runs upward and medially to attach to a spinous process two to four segments above its origin. Because its short, obliquely oriented fibres bridge only a few segments, its principal role is to stabilise the vertebrae segment by segment, while also helping to extend the spine and rotate it toward the opposite side. It is supplied by the posterior (dorsal) rami of the lumbar spinal nerves. The lumbar multifidus is especially thick and is a key focus of core stability and low-back rehabilitation.
Origin, Insertion, Action & Nerve
Origin
Posterior sacrum, posterior superior iliac spine, and mammillary processes of the lumbar vertebrae
Insertion
Spinous processes of vertebrae two to four segments superior to the origin
Action
Stabilizes the vertebrae; extends and rotates the lumbar spine to the opposite side
Nerve
Posterior (dorsal) rami of lumbar spinal nerves
Attachments explained
The Multifidus Lumborum is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Posterior sacrum, posterior superior iliac spine, and mammillary processes of the lumbar vertebrae
Insertion
Spinous processes of vertebrae two to four segments superior to the origin
Action & function
When the Multifidus Lumborum contracts, it produces the following movements: Stabilizes the vertebrae; extends and rotates the lumbar spine to the opposite side.
As part of the Back group of the Trunk, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Multifidus Lumborum receives its nerve supply from the Posterior (dorsal) rami of lumbar spinal nerves.
Because a muscle can only contract when its nerve is intact, injury to the Posterior can weaken or paralyse the Multifidus Lumborum, impairing the movements it normally produces (stabilizes the vertebrae). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Multifidus Lumborum (the OIANS method)
Picture lumbar multifidus as a stack of short, obliquely oriented straps, each spanning only two to four segments from a lower origin up to a spinous process. Because the fibres are short and close to the joints they cross, their dominant job is fine segmental stabilisation of the lumbar spine rather than gross movement, with extension and opposite-side rotation as secondary actions.
Give this muscle clinical weight: it is unusually thick in the lumbar region and central to core stability, and its wasting is strongly associated with chronic low-back pain, which is why it features so heavily in rehabilitation. Place it in the transversospinales layer between semispinalis (more superficial, longer) and rotatores (deeper, shortest) to keep the relative fibre lengths straight in your mind.
Frequently asked questions
Where is the Multifidus Lumborum located?
The Multifidus Lumborum is a muscle of the Back group, located in the Trunk.
What is the origin of the Multifidus Lumborum?
Posterior sacrum, posterior superior iliac spine, and mammillary processes of the lumbar vertebrae
What is the insertion of the Multifidus Lumborum?
Spinous processes of vertebrae two to four segments superior to the origin
What movements does the Multifidus Lumborum produce?
Stabilizes the vertebrae; extends and rotates the lumbar spine to the opposite side
What nerve supplies the Multifidus Lumborum?
Posterior (dorsal) rami of lumbar spinal nerves
Is the Multifidus Lumborum free to study in OIANS?
The Multifidus Lumborum is always free to browse. Its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory. Quiz and Flashcard practice for the Trunk is part of the one-time Lifetime upgrade, though; only the Upper Limb decks are free to test yourself on.
Related muscles
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