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Lateral intertransversarii lumborum muscle

The lateral intertransversarii lumborum are small paired muscles of the deep intrinsic back musculature. They extend between adjacent lumbar transverse processes and belong to the segmental stabilizing muscles of the vertebral column. Though small, they are clinically and functionally significant as they contribute to fine control of lumbar motion and stability. They are part of the intertransversarii group, which also includes medial fibers.

These muscles are important for postural support and segmental stability, and may become hypertrophic, atrophic, or edematous in degenerative spine disease, trauma, or chronic low back pain syndromes.

Synonyms

  • Lumbar lateral intertransversarii

  • Lateral intertransverse muscles of the lumbar spine

  • Lumbar intertransversales laterales

Origin, Course, and Insertion

  • Origin: Arises from the transverse process of one lumbar vertebra

  • Course: Short fibers pass almost vertically to adjacent transverse process

  • Insertion: Attaches onto the transverse process of the vertebra immediately below

Relations

  • Anteriorly: Lumbar sympathetic trunk, psoas major muscle

  • Posteriorly: Deep back muscles (erector spinae, multifidus)

  • Laterally: Quadratus lumborum muscle

  • Medially: Medial intertransversarii and vertebral bodies

Function

  • Provide segmental stabilization of the lumbar spine

  • Assist in lateral flexion of the trunk (ipsilateral contraction)

  • Contribute to proprioception and fine motor control of vertebral movement

  • Play a role in postural balance during standing and locomotion

Clinical Significance

  • Can be involved in lumbar instability and chronic low back pain

  • May undergo atrophy or fatty infiltration in degenerative spine disease

  • Hypertrophy or spasm can cause paraspinal stiffness

  • Serve as landmarks in MRI and CT evaluation of lumbar musculature

  • Important in assessing paraspinal muscle quality in surgical planning or rehabilitation

MRI Appearance

T1-weighted images:

  • Muscle shows low-to-intermediate signal intensity

  • Fatty infiltration appears bright

  • Surrounded by high-signal retroperitoneal fat, enhancing visibility

T2-weighted images:

  • Muscle shows intermediate signal intensity

  • Edema, inflammation, or strain appears bright

STIR (Short Tau Inversion Recovery):

  • Normal muscle: low-to-intermediate signal

  • Pathology (edema, myositis, injury): bright hyperintensity

T1 Fat-Sat Post-Contrast:

  • Normal muscle: mild homogeneous enhancement

  • Pathology: focal or diffuse enhancement in inflammation, infection, or tumor infiltration

3D T2 SPACE / CISS:

  • Muscle fibers show intermediate signal intensity compared to surrounding fat

  • Bright CSF in adjacent neural foramina highlights paraspinal muscle boundaries

  • Useful for delineating nerve vs. muscle in foraminal entrapments

CT Appearance

Non-Contrast CT:

  • Muscle appears as homogeneous soft tissue density lateral to lumbar transverse processes

  • Fat infiltration appears as low attenuation regions

  • Calcification or chronic fibrosis may rarely be seen

Post-Contrast CT:

  • Normal muscle enhances mildly and uniformly

  • Pathological muscle (abscess, tumor, inflammation) shows heterogeneous or rim enhancement

  • Perimuscular fat stranding may indicate inflammation or infection

MRI image

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

MRI image

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

MRI image

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

CT image

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