Axillary artery

Last revised by Yoshi Yu on 2 Apr 2023

The axillary artery represents the continuation of the subclavian artery and is a major artery of the upper limb.

The axillary artery is the continuation of the subclavian artery as it passes behind the midpoint of the clavicle on the outer edge of the first rib. This is also the point where the artery enters the axilla.

It descends in the axilla posterior to the axillary vein, passing posterior to the pectoralis minor and anterior to the teres major muscle. At the inferior border of teres major, it continues as the brachial artery.

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

  • first (suprapectoral) part: from its origin at the lateral edge of the first rib to superior border of pectoralis minor

  • second (retropectoral) part: posterior to pectoralis minor

  • third (infrapectoral) part: from the inferior border of pectoralis minor to inferior border of teres major

A useful mnemonic to remember its branches can be found here.

The cords of the brachial plexus are closely related to the axillary artery 1:

  • at the first part of the axillary artery, the lateral and posterior cords lie superolateral, whereas the medial cord lies posteriorly; a loop connecting the medial and lateral pectoral nerves also lies anterior to the axillary artery

  • at the second part of the axillary artery, the posterior, lateral and medial cords embrace the artery as per their names

  • at the third part of the axillary, the cords then branch into their respective peripheral nerves

Branches from the axillary artery are highly variable. In one study, variations of the subscapular artery and posterior circumflex humeral artery were noted in ~65% of the cases, and could be grouped into five main categories:

  • high origin of the subscapular artery from the second part of the axillary artery

  • common trunk for subscapular artery and posterior circumflex humeral artery from the second part of the axillary artery

  • common trunk for subscapular artery and posterior circumflex humeral artery from the third part of the axillary artery

  • common trunk for subscapular artery and posterior circumflex humeral artery with the thoracodorsal artery originating directly from the axillary artery

  • common trunk for subscapular artery, posterior circumflex humeral artery and deep brachial artery

  • anomalous high division into radial and ulnar arteries

  • absence of lateral thoracic artery (replaced by lateral perforating branches of the intercostal arteries)

  • alar thoracic artery: supplies the fat, skin and lymph nodes of the axilla 3

The thoracoacromial artery, though, appeared to originate from the first or second part of the axillary artery in all cases 2.

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