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Levatores costarum muscle

The levatores costarum muscles are a group of 12 small paired muscles of the deep back, located in the thoracic region. Each muscle originates from the tip of a thoracic transverse process (C7–T11) and descends inferolaterally to attach to the rib immediately below (brevis form) or, in some cases, the second rib below (longus form).

They are thin, triangular muscles covered by the erector spinae and serratus posterior superior. Functionally, they assist in elevating the ribs during inspiration and may play a minor role in lateral flexion and rotation of the thoracic spine. Though small, they are important in the biomechanics of thoracic cage movement and posture.

Synonyms

  • Musculi levatores costarum

  • Rib elevators

  • Posterior thoracic costal elevators

Function

  • Elevate the ribs, aiding inspiration

  • Contribute to thoracic spine stabilization

  • Assist in lateral flexion and rotation of the thoracic vertebrae

Nerve Supply

  • Dorsal rami of thoracic spinal nerves (C8–T11)

Arterial Supply

  • Posterior intercostal arteries (branches of thoracic aorta)

  • Deep cervical artery (upper muscles)

  • Lumbar arteries (for lowest segments)

Venous Drainage

  • Posterior intercostal veins → azygos system (right) and hemiazygos system (left)

  • Deep cervical vein (upper thoracic levels)

MRI Appearance

T1-weighted images:

  • Normal muscles appear as intermediate signal intensity with fascicular pattern

  • Fat infiltration (chronic denervation/atrophy) appears as high signal

T2-weighted images:

  • Normal muscles show intermediate-to-low signal

  • Acute strain, inflammation, or edema appears hyperintense

STIR:

  • Suppresses fat and highlights muscle edema, trauma, or inflammation as hyperintense regions

  • Useful for detecting subtle muscle pathology

T1 Post-Gadolinium (Gd-enhanced MRI):

  • Normal muscles enhance mildly and uniformly

  • Pathology (infection, myositis, neoplasm) enhances more prominently

MRI Non-Contrast 3D Imaging:

  • Depicts detailed spatial orientation of muscle origins on thoracic transverse processes and insertions on ribs

  • Useful for anatomical and surgical planning studies

CT Appearance

Non-contrast CT:

  • Muscles appear as small soft-tissue structures running obliquely between transverse processes and ribs

  • Limited visualization unless hypertrophied or atrophied

CT Post-Contrast:

  • Enhances surrounding vascular anatomy and helps distinguish muscles from adjacent vessels and fat

  • Useful in evaluating mass lesions, infections, or rib pathology involving muscle insertions

MRI image

Levatores costarum muscle muscle muscle anatomy MRI axial image -img-00000-00000

CT image

Levatores costarum muscle muscle muscle anatomy CT axial image -img-00000-00000