The Aorta is the largest artery in the human body, carrying oxygen-rich blood away from the heart’s left ventricle to the rest of the body. After ascending briefly, this vessel makes a characteristic backward and leftward curve over the top of the heart, a segment known as the Aortic Arch. This curved section gives rise to the major blood vessels that supply the upper extremities, neck, and head. The Aortic Arch ensures that the brain and upper body receive the high-pressure blood flow they require.
Naming the Three Main Branches
The Aortic Arch gives rise to three main arterial branches that emerge from the right side of the curve to the left. The first vessel to arise is the Brachiocephalic Artery, sometimes referred to as the Brachiocephalic Trunk. Following this first branch is the Left Common Carotid Artery. The third and final vessel to branch directly from the Aortic Arch is the Left Subclavian Artery. This trio of vessels ensures the distribution of blood to the right arm and head, the left side of the head, and the left arm, respectively.
The Brachiocephalic Artery and Its Subdivision
The Brachiocephalic Artery is the first and largest branch of the Aortic Arch. This artery is short, typically measuring four to five centimeters in length, and travels upward and to the right before quickly dividing, or bifurcating, near the upper border of the right sternoclavicular joint. This bifurcation makes the single Brachiocephalic artery responsible for supplying the entire right upper quadrant of the body. The two resulting vessels are the Right Common Carotid Artery, which supplies the right side of the head and neck, and the Right Subclavian Artery, which carries blood to the right arm. The brachiocephalic artery thus acts as a common trunk for both the right arm and the right side of the head and neck.
Direct Supply to the Head and Neck
The Left Common Carotid Artery emerges as the second main branch directly from the Aortic Arch. The left vessel has a substantial presence in the chest before ascending into the neck. Its primary function is to deliver oxygenated blood to the structures of the left side of the head and neck. The artery ascends the neck without giving off any major branches until it reaches the level of the fourth cervical vertebra, where it divides into two separate vessels: the Internal Carotid Artery and the External Carotid Artery. The External Carotid Artery supplies the face, scalp, tongue, and neck structures external to the cranium, while the Internal Carotid Artery travels into the skull to become a major contributor to the cerebral circulation, supplying the anterior portion of the brain with oxygen and nutrients.
Direct Supply to the Upper Extremity
The Left Subclavian Artery is the third branch to arise directly from the Aortic Arch. This vessel passes beneath the clavicle, or collarbone, which is how it gets the name “subclavian.” Its main role is the supply of blood to the entire left upper extremity, nourishing the muscles of the shoulder, chest, and arm. The Left Subclavian Artery is also a source of blood for the brain’s posterior circulation. One of its earliest branches is the Left Vertebral Artery, which travels upward through the neck vertebrae. This vertebral artery joins its counterpart from the right side to form the Basilar Artery, supplying the brainstem, cerebellum, and the posterior part of the cerebrum.