Left subclavian artery

Arteria subclavia sinistra

CardiovascularBlood vesselsThoraxLeft side

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What it is

Arises directly from the aortic arch and arches laterally over the dome of the pleura and the first rib, passing behind the anterior scalene muscle; at the outer border of the first rib it becomes the axillary artery.

Function

Supplies the arm and, through the vertebral, internal thoracic and thyrocervical branches, the brain, chest wall and neck.

Size

~9 mm diameter; ~6–9 cm long.

Clinical note

Narrowing near its origin can make the vertebral artery flow backwards when the arm is exercised ("subclavian steal").