The Anatomy of the Brachiocephalic Artery

The first and largest branch of the aortic arch

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The brachiocephalic artery is a blood vessel that originates from the aortic arch. It feeds blood flow to the right carotid artery and the right subclavian artery. It is also known as the innominate artery or the brachiocephalic trunk. The name refers to the fact that blood flows through this very short artery to the arm (brachio) and the head (cephalic). It is an artery, meaning that it is a thick-walled blood vessel that carries blood away from the heart. It can also be called a trunk because it is the base for two other very important arteries.

Anatomy

The brachiocephalic artery is only about 4 to 5 centimeters (cm) in length from the aortic arch to the point where it bifurcates into the right subclavian artery and the right carotid artery. It originates at the point where the ascending aorta begins to curve into the aortic arch, just at the midline.

The brachiocephalic artery branches to the right subclavian artery and the right carotid artery.

There is only one brachiocephalic artery and it only feeds the right arm and the right side of the brain.

The left arm and left side of the brain are supplied with blood from two other arteries that are attached to the aortic arch distal (downstream) to the brachiocephalic artery.

The brachiocephalic artery is superior to the aortic arch and inferior to the thymus gland. The trachea sits right between the brachiocephalic artery and the left common carotid. The brachiocephalic artery follows the right side of the trachea up to the level of where the clavicle meets the sternum.

The brachiocephalic artery continues to the right arm in an almost straight line with the right common carotid artery rising up from just behind the sternoclavicular joint.

Anatomical Variations

A congenital variant of the aortic arch that affects the brachiocephalic artery is called a bovine arch. This variation occurs in as much as 27% of the population and is more common in African-Americans.

A bovine arch is so named because the branches of the brachiocephalic artery and the left common carotid artery all originate together from the aortic arch, instead of being separated as is typical. On an X-ray, the entire thing looks a little like the head of a cow with horns. There are two additional variations of the bovine arch that are much less common.

Most anatomical variations of the brachiocephalic artery are asymptomatic (have no medical complaints).

Function

The brachiocephalic artery carries blood from the aorta to the right side of the brain and the right arm. This is a large blood vessel that provides most of the blood flow to these areas.

Despite the fact that there are two arms and two sides of the brain, the brachiocephalic artery only occurs once and only supplies the right arm and right side of the brain. The left common carotid artery supplying the left side of the brain and the left subclavian artery supplying the left arm are not combined and both arise along the aortic arch distal to the brachiocephalic artery.

As small as the brachiocephalic artery is, it plays a significant role in pressure regulation by controlling the blood flow between the aortic arch and the right common carotid artery.

In some cases of bypass surgery that bypass the brachiocephalic artery and carry blood directly from the aortic arch to the carotid artery, overflow of blood into the carotid stimulate the baroreceptors there to trigger a significant fall in blood pressure.

Clinical Significance

The brachiocephalic artery and subclavian artery are the most common locations for lesions that cause narrowing (stenosis) and restrict blood flow to the upper extremities. Brachiocephalic stenosis can cause pain in the right arm with exercise, vision problems, and transient ischemic attacks.

More distal (further downstream) narrowing of the blood vessels can lead to a condition called subclavian steal syndrome, which actually steals blood flow from the brain and shunts it to the arm. Subclavian steal syndrome can cause neurological symptoms similar to a stroke and are usually worse during exercise that causes the arm to pull more blood flow.

Often referred to as innominate artery disease, narrowing and occlusions to the brachiocephalic artery can be treated through various surgical methods.

  • Endarterectomy is a surgical procedure used to remove plaque from the inside of arteries. It is often used on the carotid arteries to prevent stroke.
  • Angioplasty is the use of a balloon inflated inside narrowed arteries to force them open. Once the artery is open, a stent is placed to hold it there. A stent looks a bit like a small spring.
  • Bypass surgery takes a segment of another blood vessel and grafts it to a point proximal (upstream) and distal (downstream) to the occlusion in the brachiocephalic artery. It allows blood to flow around (bypass) the occlusion.

An aneurysm in the brachiocephalic artery is rare but clinically significant. The brachiocephalic artery is the location of aneurysms in 3% of all supra-aortic aneurysms. These aneurysms can grow and put pressure on surrounding tissues and structures, causing difficulty swallowing or shortness of breath. They can also create blood clots that might travel downstream to more distal locations. Doctors usually treat brachiocephalic artery aneurysm through surgical repair.

Anatomical variations of the brachiocephalic artery are usually asymptomatic, but they are common and pose a greater risk of rupture and ischemia (restricted circulation) during surgical procedures in the chest. It is important for people who know they have a variation to report that to their doctors, especially if surgery is possible.

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Article Sources

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