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Circumflex scapular artery

The circumflex scapular artery is a major branch of the subscapular artery, which itself arises from the third part of the axillary artery. It courses posteriorly through the triangular space (bounded by the teres minor, teres major, and long head of the triceps brachii) to reach the infraspinous fossa of the scapula. The artery supplies the posterior scapular muscles and anastomoses with branches of the suprascapular artery and dorsal scapular artery, forming part of the scapular arterial anastomosis that maintains blood flow to the shoulder and scapula, especially during arm movements or when proximal vessels are occluded.

Synonyms

  • Posterior scapular circumflex artery

  • Branch of the subscapular artery

  • Arteria circumflexa scapulae

Function

  • Provides arterial supply to the infraspinatus, teres major, teres minor, and parts of the subscapularis muscle

  • Contributes to the scapular arterial anastomosis, ensuring collateral circulation around the scapula and shoulder joint

  • Maintains blood flow during dynamic shoulder movements and in cases of proximal arterial obstruction

MRI Appearance

T1-weighted images:

  • Appears as a flow void (signal loss, black lumen) due to rapid blood flow

  • Vessel wall is not well seen without contrast

  • Surrounded by intermediate signal muscle and hyperintense fat planes

T2-weighted images:

  • Blood flow continues to appear as signal void

  • Surrounding edema or pathology in scapular muscles appears hyperintense, outlining the artery’s course indirectly

STIR (Short Tau Inversion Recovery):

  • Fat suppression improves visualization of adjacent muscle edema, inflammation, or trauma

  • Artery itself remains signal void, but pathology along its course can be highlighted

T1 Post-Contrast (Gadolinium-enhanced):

  • Lumen demonstrates bright, homogeneous enhancement

  • Clearly depicts the course through the triangular space and its contribution to the scapular anastomosis

  • Useful for detecting stenosis, aneurysm, vascular malformations, or collateral circulation

CT Appearance

Non-contrast CT:

  • The artery is not easily visualized without contrast, seen only as a small soft tissue density within fat planes near the triangular space

  • Calcified arterial wall (rare) appears hyperdense

CT Angiography (CTA):

  • Provides clear visualization of the origin from the subscapular artery, course through the triangular space, and distribution in the scapular region

  • Demonstrates its anastomoses with suprascapular and dorsal scapular arteries

  • Excellent for evaluating vascular trauma, scapular fractures with arterial involvement, or preoperative planning for flap surgeries

CT images

Circumflex scapular artery anatomy CT axial image -img-00000-00000

CT images

Circumflex scapular artery anatomy CT axial image -img-00000-00000_00001

MRI image

Circumflex scapular artery anatomy CT axial image -img-00000-00000_00002