Axillary artery

After passing the lower margin of teres major it becomes the brachial artery.

Structure

The axillary artery is often referred to as having three parts, with these divisions based on its location relative to the pectoralis minor muscle, which is superficial to the artery.

• First part – the part of the artery superior to the pectoralis minor
• Second part – the part of the artery posterior to the pectoralis minor
• Third part – the part of the artery inferior to the pectoralis minor.

Relations

The axillary artery is accompanied by the axillary vein, which lies medial to the artery, along its length.

In the axilla, the axillary artery is surrounded by the brachial plexus. The second part of the axillary artery is the reference for the locational descriptions of the cords in the brachial plexus. For example, the posterior cord of the brachial plexus is so named because it lies posterior to the second part of the artery.

Branches

The axillary artery has several smaller branches. The branches can be remembered, in order, when traveling from the heart, with the mnemonics "Seek The Lord, Serve All People", "Summertime: The Lakers Schedule Another Parade", "Some Traumas Leave Scars And Pain", or "She Tastes Like Sweet Apple Pie." The origin of these branches is highly variable (e.g. the posterior and anterior circumflex arteries often have a common trunk). An arterial branch is named for its course, not its origin.

• First part (1 branch)
  • Superior thoracic artery (Supreme thoracic artery)
• Second part (2 branches)
  • Thoraco-acromial artery
  • Lateral thoracic artery. If the lateral thoracic artery is not branching from the axillary artery, will most likely branch from the following (in order of likelihood): (1) thoracoacromial, (2) third part of axillary artery, (3) suprascapular artery, (4) subscapular artery
• Third part (3 branches)
  • Subscapular artery
  • Anterior humeral circumflex artery
  • Posterior humeral circumflex artery

Continues as the brachial artery past the inferior border of the teres major.