Axillary a.

The axillary artery is a large blood vessel that conveys oxygenated blood to the lateral aspect of the thorax, the axilla (armpit) and the upper limb.

Its origin is at the lateral margin of the first rib, medial to which it is called the subclavian a. After passing the inferior margin of teres major m. it becomes the brachial a.

The axillary artery is often referred to as having three parts based on its relationship with the pectoralis minor m. The pectoralis minor m. passes superficial to the artery.

• First part - the part of the axillary artery medial to pectoralis minor

• Second part - the part of the axillary artery that lies posterior to pectoralis minor

• Third part - the part of the axillary artery lateral to pectoralis minor

The axillary artery has several branches. The origin of these branches is highly variable (e.g. the posterior and anterior circumflex arteries often arise from a common trunk). An arterial branch is named for the structures it supplies, not its origin.

• The first part of the axillary artery has 1 branch:

• Superior thoracic artery (Supreme thoracic artery)

• The second part of the axillary artery has 2 branches:

• Thoraco-acromial artery

• Lateral thoracic artery - note that if the lateral thoracic artery is not a branch of the second part of the axillary artery, it 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

• The third part of the axillary artery has 3 branches:

• Subscapular artery

• Anterior humeral circumflex artery

• Posterior humeral circumflex artery

The branches can be remembered, in order, when traveling from the heart, with the mnemonic "Screw The Lawyers, Save A Patient". The axillary artery continues as the brachial artery past the inferior border of the teres major m. into the arm.