Subclavia

Subclavia is the anatomical term used for structures located beneath the clavicle, most notably the subclavian artery and the subclavian vein, which form a key conduit between the thorax and the upper limb. The term is used in several languages and in medical literature to denote this vascular region and its major vessels, as well as the surrounding anatomy.

The subclavian artery originates on the right from the brachiocephalic trunk and on the left directly from the aortic arch. It courses laterally, passing over the first rib, and becomes the axillary artery at the lateral border of the first rib. It is traditionally described as having three parts, divided by the anterior scalene muscle. The proximal part gives rise to branches such as the vertebral artery, thyrocervical trunk, and internal thoracic artery. The second part lies behind the scalene and commonly gives the costocervical trunk. The third part extends to the outer border of the first rib and provides smaller branches to the thorax and shoulder region.

The subclavian vein is formed behind the sternoclavicular joint by the union of the external and internal jugular veins and runs medially to the subclavian artery, becoming the brachiocephalic vein behind the clavicle. The left subclavian vein contributes to the formation of the left venous angle with the left internal jugular, into which the thoracic duct drains; the right venous angle involves the right subclavian and right internal jugular veins. Clinical considerations include thoracic outlet syndrome, which can involve compression of the subclavian vessels or the brachial plexus.

Etymology derives from Latin subclavia, literally “below the clavicle.”