Subklavia

Subklavia, or subclavian, refers to the region beneath the clavicle. In human anatomy, the term mainly denotes the subclavian artery and the subclavian vein, two major vessels that supply and drain the upper limb.

The subclavian artery originates on the right from the brachiocephalic trunk and on the left directly from the aortic arch. It courses laterally, behind the scalenus anterior muscle and over the first rib, and becomes the axillary artery at the lateral border of the first rib. It is commonly described as having three parts relative to the anterior scalene muscle. Branches typically include the vertebral artery, internal thoracic (mammary) artery, and thyrocervical trunk from the first part; the costocervical trunk from the second part; and occasional dorsal scapular branches. The artery supplies structures of the upper limb, as well as parts of the neck and thorax, and contributes to the brain's blood supply via the vertebral artery.

The subclavian vein travels superiorly and medially, anterior to the scalenus anterior muscle, and passes behind the clavicle. It becomes the axillary vein at the lateral border of the first rib and drains into the brachiocephalic vein when it joins with the internal jugular vein. Tributaries include several veins such as the external jugular, internal thoracic veins, and vertebral veins. The venous system of the subclavian region drains the upper limb, portions of the thorax, and the neck.

Clinical relevance includes central venous access via the subclavian vein and the risks of pneumothorax or vessel injury; thoracic outlet syndrome due to compression of the subclavian vessels or brachial plexus; and subclavian steal syndrome, where proximal subclavian stenosis causes retrograde flow in the vertebral artery. Variations exist in origin, branching, and symmetry between sides.