Axillary artery: boundaries, three parts and branches

Where does the axillary artery run?

The artery from below the clavicle to the upper arm changes its name twice: subclavian, axillary, brachial. The middle segment, through the armpit, is the axillary artery.

In the view above it is yellow, with the subclavian artery before it and the brachial artery after it in red. It passes under the clavicle, deep into the armpit and past the inner side of the shoulder joint toward the arm. It is named from the outer border of the first rib to the lower border of teres major; the vessel itself is continuous and does not change at these points.

Three parts defined by pectoralis minor

Around the second part lie the three cords of the brachial plexus; their names, lateral, medial and posterior, describe their position relative to this part of the artery. The axillary vein lies medial to the artery.

One, two, three branches

The posterior circumflex humeral artery passes with the axillary nerve through the quadrangular space, bounded in part by teres minor, to reach the deltoid. Branching patterns vary a lot, with shared trunks common; the one-two-three rule is a memory aid for the typical pattern.

Name and terms

Axillary comes from the Latin axilla, armpit. Related terms: pectoralis minor, thoracoacromial artery, subscapular artery. The Latin is arteria axillaris.

See it in the app

Hidden behind the clavicle and chest muscles, where the axillary artery starts and ends is hard to see in drawings. In the 3D anatomy app teamLabBody you can keep only the bones and vessels, select the axillary artery and see its boundaries with the subclavian and brachial arteries, then add the muscles to see it pass behind pectoralis minor. Cross sections are available with the PREMIUM plan.

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