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Medial intertransversarii lumborum

The medial intertransversarii lumborum are small paired muscles located in the lumbar spine. They belong to the deep intrinsic muscles of the back and lie between adjacent vertebrae. Unlike their lateral counterparts, the medial intertransversarii run between the mammillary process of one vertebra and the accessory process of the vertebra below, contributing to fine motor control and stabilization of the lumbar spine.

Though small, they are important in maintaining segmental alignment of the vertebrae and assisting proprioception of the spine.

Synonyms

  • Lumbar medial intertransversarii

  • Medial lumbar intertransversarii muscles

  • Short medial stabilizers of the lumbar spine

Origin, Course, and Insertion

  • Origin: Mammillary process of a lumbar vertebra

  • Course: Runs vertically downward between adjacent vertebrae

  • Insertion: Accessory process of the vertebra immediately below

Relations

  • Anteriorly: Lumbar vertebral bodies and intervertebral discs

  • Posteriorly: Multifidus and erector spinae muscles

  • Medially: Spinous processes and interspinous ligaments

  • Laterally: Lateral intertransversarii lumborum (between transverse processes)

Function

  • Stabilizes adjacent lumbar vertebrae during movement

  • Assists in fine-tuning posture and segmental motion

  • Provides proprioceptive feedback for spinal control

  • Contributes minimally to lateral flexion when acting bilaterally with other muscles

Clinical Significance

  • May be involved in lumbar instability and microtrauma

  • Atrophy or fatty replacement can be seen in chronic low back pain

  • Important in biomechanical studies of spine stabilization

  • Visible in high-resolution MRI and may be confused with small nerve or vessel structures if not recognized

MRI Appearance

T1-weighted images:

  • Muscle shows low-to-intermediate signal intensity

  • Surrounded by bright fat between vertebral structures

T2-weighted images:

  • Muscle demonstrates intermediate signal intensity

  • Pathological changes (strain, edema) appear as brighter signal

STIR (Short Tau Inversion Recovery):

  • Normal muscle shows low-to-intermediate signal

  • Inflammation or edema appears bright hyperintense

T1 Fat-Sat Post-Contrast:

  • Normal muscle enhances mildly and uniformly

  • Pathologic muscle (inflammation, infection, neoplasm) enhances heterogeneously

3D T2 SPACE / CISS:

  • Muscle shows intermediate signal compared to surrounding fat and CSF

  • Excellent sequence for identifying its anatomical separation from adjacent nerves and vessels

CT Appearance

Non-Contrast CT:

  • Appears as a small soft tissue density between adjacent vertebrae

  • Surrounded by fat planes and bone landmarks (mammillary and accessory processes)

Post-Contrast CT:

  • Muscle shows mild homogeneous enhancement

  • Pathology may cause asymmetric thickening, mass-like enhancement, or obliteration of surrounding fat planes

MRI image

Medial intertransversarii lumborum muscle MRI axial anatomy image-img-00000-00000

MRI image

Medial intertransversarii lumborum muscle MRI axial anatomy image-img-00000-00000_00001

MRI image

Medial intertransversarii lumborum muscle MRI SAGITTAL anatomy image-img-00000-00000

MRI image

Medial intertransversarii lumborum muscle MRI SAGITTAL anatomy image-img-00000-00000_00001

CT image

Medial intertransversarii lumborum muscle CT axial anatomy image-img-00000-00000