Left subclavian artery (anatomy)

The left subclavian artery is the third main branch of the arch of the aorta. It originates posterior and slightly lateral to the left common carotid artery at the level of the intervertebral disc between T3 and T4. It passes superiorly so that it is deep to the left sternoclavicular joint. Then, it passes laterally. It terminates as the left axillary artery at the outer border of the first rib.

As with the right subclavian artery, it can be divided into three parts according to its relationship to the scalenus anterior muscle:

• first part: from arch of aorta to medial border of scalenus anterior
• second part: deep to scalenus anterior
• third part: lateral border of scalenus anterior to the lateral border of first rib