The aortic arch is a curved segment of the body’s largest artery, the aorta, situated within the chest cavity. This vessel is an upward continuation of the ascending aorta, curving over the top of the heart before descending. Its primary function is to distribute oxygen-rich blood that has just left the heart’s left ventricle. The arch ensures this blood reaches the upper parts of the body.
Naming the Three Primary Branches
Three large arteries emerge sequentially from the top of the aortic arch. These vessels deliver the entire blood supply to the head, neck, and both upper limbs. The first branch is the Brachiocephalic Trunk, positioned furthest to the right. The Left Common Carotid Artery emerges as the second branch. The third major branch is the Left Subclavian Artery, which is the last to arise before the aorta begins its downward course.
The Brachiocephalic Trunk and Its Role
The Brachiocephalic Trunk, sometimes referred to as the innominate artery, is the only main branch that immediately splits into two major terminal vessels. This single short artery typically measures about four to five centimeters in length. It courses upward and to the right, acting as a common stem for two major arterial pathways on the right side of the body.
Division of the Trunk
The trunk terminates by splitting behind the right sternoclavicular joint. This division forms the Right Common Carotid Artery and the Right Subclavian Artery. The Right Common Carotid Artery supplies the right side of the head and neck, including the brain and face. The Right Subclavian Artery arches laterally to supply the entire right upper limb.
The Direct Branches: Left Carotid and Left Subclavian
The two remaining vessels arise directly from the aortic arch, establishing a pattern of asymmetry in the upper body’s arterial supply. The Left Common Carotid Artery originates as the second branch and ascends into the neck. It carries oxygenated blood to the structures on the left side of the head and neck. Like all common carotid arteries, it eventually divides higher up to supply both internal structures, such as the brain, and the external face and scalp.
The third vessel, the Left Subclavian Artery, also emerges directly from the aortic arch and arches toward the left upper limb. This artery is the primary source of blood for the entire left arm. The direct origin of these left-sided arteries distinguishes the left side of the body’s vascular anatomy from the right.