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Lateral thoracic artery

The lateral thoracic artery is a variable branch of the second part of the axillary artery, though it may also arise from the thoracoacromial artery, suprascapular artery, or subscapular artery. It descends along the lateral thoracic wall, running with the long thoracic nerve on the surface of the serratus anterior muscle. The artery primarily supplies the lateral chest wall, serratus anterior, pectoral muscles, and breast tissue, with branches contributing to the mammary gland and axillary lymph nodes. Its caliber and prominence are clinically important in breast surgery, reconstructive surgery, and angiographic procedures.

Synonyms

  • External mammary artery

  • Thoracic external artery

  • Lateral chest wall artery

Function

  • Supplies the lateral thoracic wall and serratus anterior muscle

  • Provides branches to the pectoralis muscles and mammary gland

  • Contributes to the vascular supply of axillary lymph nodes

  • Participates in collateral circulation of the thoracic wall

MRI Appearance

T1-weighted images:

  • Vessel lumen appears as a signal void (black) due to flowing blood

  • Surrounded by intermediate signal muscle and hyperintense fat, enhancing anatomical localization

  • Useful for evaluating adjacent breast and chest wall tissues

T2-weighted images:

  • Flowing blood produces a signal void within the artery

  • Surrounding fat is hyperintense, providing contrast for artery identification

  • Pathology such as aneurysm or thrombosis may alter expected signal

STIR (Short Tau Inversion Recovery):

  • Fat suppression improves visualization of the artery against the chest wall

  • Vessel lumen remains signal void, but surrounding inflammation, edema, or mass lesions appear hyperintense

T1 Post-Contrast (Gadolinium-enhanced):

  • Artery demonstrates intense homogeneous enhancement

  • Enhances visualization of small branches to breast, pectoral muscles, and serratus anterior

  • Useful in breast tumor angiography or pre-surgical mapping

CT Appearance

Non-contrast CT:

  • Artery is seen as a tubular soft tissue density structure along the lateral thoracic wall

  • Lumen is not well visualized without contrast, but calcifications (rare) appear hyperdense

Contrast-enhanced CT (CT Angiography):

  • Lateral thoracic artery is well-opacified, allowing detailed evaluation of origin, course, and branches

  • Provides high-resolution mapping for breast surgery, tumor evaluation, and reconstructive planning

  • Multiplanar reconstructions delineate the artery in relation to the axilla and thoracic wall structures

CT images

Lateral thoracic artery anatomy CT axial image -img-00000-00000

MRI images

Lateral thoracic artery anatomy MRI coronal image -img-00000-00000