The brachial plexus and subclavian artery pass between the anterior and middle scalenes. This variant may predispose the phrenic nerve to injury during subclavian vascular cannulation. The brachial plexus and the subclavian artery pass anterior to it. The left and right external jugular veins drain into the subclavian veins. The coarctation typically occurs after the left subclavian artery. Fainting may result from subclavian steal syndrome or carotid sinus hypersensitivity. Upper extremity DVT most commonly affects the subclavian, axillary, and jugular veins. The vertebral arteries arise from the subclavian arteries. TOS can be related to cerebrovascular arterial insufficiency when affecting the subclavian artery. The brachiocephalic vein is formed by the confluence of the subclavian and internal jugular veins. The thoracic duct empties the chylomicrons into the bloodstream via the left subclavian vein. In SSS a reduced quantity of blood flows through the proximal subclavian artery. Typically, the vertebral arteries originate from the subclavian arteries. The vertebral arteries emerge as branches of the left and right subclavian arteries. Rarely, the celiac axis, internal mammary, subclavian, or renal artery may be involved.