The subclavian arteries provide blood supply to both upper extremities and give rise to major arterial branches, including the vertebral arteries, the internal thoracic arteries, and the costocervical and thyrocervical trunks. The internal thoracic artery is also called the left internal mammary artery (LIMA). This branch of a subclavian artery is significant in its frequent use for coronary artery bypass graft (CABG) surgery. It is often used for bypass of the left anterior descending artery of the heart, and thus, if subclavian stenosis is present in such patients, coronary insufficiency can result. It is important to know that the LIMA has an anterior take off from the subclavian artery when attempting to cannulate this vessel for selective angiography.
The left subclavian artery branches directly from the aortic arch, whereas the right subclavian artery arises from the brachiocephalic trunk, also known as the innominate artery (Figure 32-1). The subclavian artery courses posteriorly to the clavicle and travels between the anterior and middle scalene muscles of the lateral neck.1
Anatomy of the subclavian artery.
The right subclavian artery may arise directly from the aorta. A so-called “bovine” aortic arch is present in about 7% of individuals where the left carotid artery arises from the innominate artery (Figure 32-2) or shares a common trunk with the innominate artery. This term is a misnomer because this variant has no relation to the aortic arch branching pattern found in cattle. In cattle, a single great vessel originates from the aortic arch. This large brachiocephalic trunk gives rise to both subclavian arteries and a bicarotid trunk. The bicarotid trunk then bifurcates into the left common carotid artery and right common carotid artery. The vertebral artery may arise not from the subclavian artery but from the aorta itself in <1% of patients (Figure 32-3).
Vertebral artery arising from the aortic arch.
The term arteria lusoria refers to an aberrant right subclavian artery. The first description of this variation was provided in 1735 by Hunauld.2 When an aberrant right subclavian artery variant is present, the brachiocephalic trunk is absent and 4 large arteries arise from the arch of the aorta: the right common carotid artery, the left common carotid artery, the left subclavian artery, and the final artery with the most distal left-sided origin, the right subclavian artery (Figure 32-4).
(A) Aortography demonstrates abnormal origin of right (RT) subclavian artery arising from the descending aorta. (B) Magnetic resonance angiogram (MRA) illustrates both the RT common ...