The brachiocephalic trunk, also called the innominate artery, is the first and largest blood vessel originating from the highest part of the aorta in the chest. This artery is a primary component of the circulatory system, channeling oxygen-rich blood from the heart. Its main purpose is to supply the right side of the body by directing blood flow toward the head, neck, and right arm.
Anatomy and Blood Flow Pathway
Arising from the aortic arch, the brachiocephalic trunk begins its course posterior to the manubrium, the upper part of the sternum. It is a relatively short vessel, typically measuring between four and five centimeters in length, as it travels upward and toward the right. This artery is situated within the superior mediastinum and is positioned anterior to the trachea and to the left of the superior vena cava.
Upon reaching the area behind the right sternoclavicular joint, where the collarbone meets the sternum, the brachiocephalic trunk divides. This bifurcation creates the right common carotid artery and the right subclavian artery. The right common carotid artery supplies blood to the right side of the neck and head, while the right subclavian artery supplies the right arm.
A feature of this vascular arrangement is its asymmetry. On the right side, the brachiocephalic trunk acts as a common origin for the carotid and subclavian arteries. However, this trunk is absent on the left side, where the left common carotid and left subclavian arteries typically arise directly from the aortic arch.
Associated Medical Conditions
Several medical conditions can affect the brachiocephalic trunk, often related to structural changes in the artery wall. An aneurysm is a localized bulge or ballooning that occurs due to a weakening of the vessel wall. These aneurysms are uncommon but carry risks associated with enlargement or rupture.
Another condition is stenosis, the narrowing of the artery. This is most commonly caused by atherosclerosis, a process where plaque accumulates on the inner arterial walls, restricting blood flow. Risk factors for developing this condition include high blood pressure, high cholesterol, and diabetes.
A tear in the inner layer of the artery’s wall is known as a dissection, which can allow blood to flow between the wall layers, obstructing blood flow. Although dissection of this artery is rare, it can lead to serious outcomes. In some cases, particularly in children, the artery can compress the nearby trachea, a condition known as innominate artery compression syndrome, which may cause breathing difficulties.
Diagnosis and Treatment Overview
To identify issues with the brachiocephalic trunk, physicians use imaging techniques for detailed visualization of the artery. Computed tomography (CT) angiography and magnetic resonance (MR) angiography provide clear images of the vessel, its branches, and any structural abnormalities. A duplex ultrasound may also be employed, which uses sound waves to assess the artery’s structure and measure the speed of blood flow.
Treatment is tailored to the specific condition, its severity, and the patient’s overall health. Medical management is a common initial approach, involving medications to control risk factors like high blood pressure and cholesterol. For significant stenosis, angioplasty with stenting may be performed to open the artery. More complex problems like large aneurysms or dissections might require open surgery to repair or replace the affected artery with a graft.