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Rotatores lumborum muscles

The rotatores lumborum are small, deep paraspinal muscles of the transversospinalis group, located in the lumbar region of the spine. They are the most underdeveloped of the rotatores muscles compared to the thoracic region, but they remain important for local stabilization of the lumbar vertebrae.

Each rotatores muscle arises from the transverse process of one vertebra and inserts onto the lamina or spinous process of the vertebra above (short rotatores) or the second vertebra above (long rotatores). Their small size and deep location make them difficult to isolate, but they are crucial for fine adjustments in spinal posture and for proprioception.

Synonyms

  • Lumbar rotatores muscles

  • Rotatores of lumbar spine

  • Deep transversospinalis muscles

Origin, Course, and Insertion

  • Origin: Arises from the transverse process of lumbar vertebrae

  • Course: Fibers run obliquely upward and medially from the transverse process toward the vertebral arch above

  • Insertion:

    • Short rotatores: Insert into the lamina of the vertebra immediately above

    • Long rotatores: Insert into the spinous process of the vertebra two levels above

Relations

  • Anteriorly: Lumbar vertebral bodies, intervertebral discs, and psoas major muscle

  • Posteriorly: Multifidus and erector spinae muscles

  • Laterally: Quadratus lumborum muscle

  • Medially: Lumbar vertebral laminae and spinous processes

Function

  • Produce small rotary movements of the lumbar vertebrae (though minimal in magnitude)

  • Function mainly as postural stabilizers of the lumbar spine

  • Provide proprioceptive feedback due to high density of muscle spindles

  • Contribute to fine-tuned adjustments during gait and trunk movement

Clinical Significance

  • May be involved in chronic low back pain syndromes due to strain or dysfunction

  • Atrophy or fatty degeneration can occur in lumbar instability or chronic spine disease

  • Can be visualized in MRI for evaluation of muscle wasting, inflammation, or paraspinal masses

  • Important in surgical approaches to the lumbar spine (deep posterior compartment)

MRI Appearance

T1-weighted images:

  • Muscles show low-to-intermediate signal intensity

  • Fat infiltration (chronic degeneration) appears as areas of high signal intensity

T2-weighted images:

  • Normal muscle: low-to-intermediate signal

  • Edema, strain, or inflammation: bright hyperintensity within the muscle fibers

STIR (Short Tau Inversion Recovery):

  • Normal muscle: low signal

  • Pathology (edema, inflammation, strain): bright hyperintensity

T1 Fat-Sat Post-Contrast:

  • Normal muscle: mild, homogeneous enhancement

  • Pathological conditions: heterogeneous or focal enhancement in inflammation, infection, or tumor

3D T2 SPACE / CISS:

  • Muscle appears as intermediate signal relative to adjacent fat (bright) and vertebrae (dark)

  • Useful for defining the fine fascicles and distinguishing them from adjacent multifidus

CT Appearance

Non-Contrast CT:

  • Muscles appear as soft tissue density in the paraspinal region

  • Fatty degeneration: seen as low attenuation areas within the muscle belly

Post-Contrast CT:

  • Normal muscle: mild, homogeneous enhancement

  • Pathology: heterogeneous or irregular enhancement in infection, tumor, or inflammatory disease

MRI image

Rotatores lumborum muscles mri axial anatomy image-img-00000-00000

CT image

Rotatores lumborum muscles cti axial anatomy image-img-00000-00000