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Axillary artery

The axillary artery is the continuation of the subclavian artery, beginning at the lateral border of the first rib and extending to the inferior border of the teres major muscle, where it becomes the brachial artery. It passes through the axilla, a neurovascular space bounded by the pectoralis major, latissimus dorsi, scapula, and humerus.

The artery is conventionally divided into three parts by its relation to the pectoralis minor muscle:

  • First part (proximal): from lateral border of first rib to medial border of pectoralis minor

  • Second part (posterior): lies posterior to pectoralis minor

  • Third part (distal): from lateral border of pectoralis minor to inferior border of teres major

The axillary artery is closely related to the axillary vein and brachial plexus cords, making it a critical landmark in surgical and interventional procedures. It provides the major blood supply to the shoulder, thoracic wall, and upper limb.

Synonyms

  • Arteria axillaris

  • Shoulder artery

  • Continuation of subclavian artery

Function

  • Supplies oxygenated blood to the shoulder girdle, thoracic wall, scapular region, and entire upper limb

  • Forms anastomoses with subclavian and brachial branches, ensuring collateral circulation

  • Provides critical vascular supply for shoulder motion and upper limb activity

Branches

  1. First part:

    • Superior thoracic artery

  2. Second part:

    • Thoracoacromial artery (pectoral, clavicular, acromial, deltoid branches)

    • Lateral thoracic artery

  3. Third part:

    • Subscapular artery (thoracodorsal & circumflex scapular branches)

    • Anterior circumflex humeral artery

    • Posterior circumflex humeral artery

MRI Appearance

T1-weighted images:

  • Axillary artery lumen appears as a flow void (black) due to rapid blood flow

  • Surrounded by hyperintense fat in the axilla, providing contrast

  • Branches can be tracked relative to muscles and brachial plexus cords

T2-weighted images:

  • Lumen remains a signal void

  • Adjacent muscles and fat create contrast for identifying vascular course

  • Abnormalities such as aneurysm or thrombus may show altered signal

STIR (Short Tau Inversion Recovery):

  • Fat suppression enhances visualization of the artery against surrounding tissue

  • Perivascular inflammation, edema, or hematoma appear hyperintense

  • Useful for trauma or vascular inflammatory conditions

T1 Post-Contrast (Gadolinium-enhanced):

  • Axillary artery and its branches show bright, homogeneous enhancement

  • Excellent for MR angiography to assess stenosis, occlusion, aneurysm, or arteriovenous malformations

  • Provides detailed mapping for surgical or interventional planning

CT Appearance

Non-contrast CT:

  • Appears as a soft tissue density tubular structure in the axilla

  • May show vascular calcification in atherosclerotic disease

CT Angiography (CTA):

  • Clearly demonstrates the origin, branching pattern, and collateral circulation

  • Best for evaluating traumatic injury, aneurysm, stenosis, or thrombosis

  • Allows 3D reconstruction for preoperative or interventional planning

CT images

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MRI images

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