The brachiocephalic artery, also known as the brachiocephalic trunk or innominate artery, is a major artery that branches directly from the aortic arch. It is the first and largest branch of the aorta, supplying blood to the right side of the head, neck, and upper limb.
Location
The brachiocephalic artery arises from the aortic arch, just to the right of the midline, and ascends superiorly and to the right. It travels upward through the superior mediastinum, located behind the right side of the sternum. After a short course, at the level of the right sternoclavicular joint, it divides into the right common carotid artery and the right subclavian artery, which supply the right side of the head, neck, and upper limb, respectively. Unlike the left side of the body, there is no brachiocephalic artery on the left, as the left common carotid and left subclavian arteries branch directly from the aortic arch.
Structure and Anatomy
Origin
The brachiocephalic artery, also known as the brachiocephalic trunk or innominate artery, is the first and largest branch of the aortic arch. It arises from the convex portion of the aortic arch in the superior mediastinum. It originates just to the right of the midline of the body, after the aorta ascends from the left ventricle and begins its arch.
Course
After arising from the aortic arch, the brachiocephalic artery travels upward and to the right through the superior mediastinum. It runs posterior to the right sternoclavicular joint and is positioned anterior to the trachea during its short but significant course.
The artery is surrounded by important structures as it ascends. Posterior to the brachiocephalic artery are the trachea and esophagus, and anteriorly, it is covered by the sternum and manubrium. The right vagus nerve and right recurrent laryngeal nerve also pass near the brachiocephalic artery, making it closely related to vital nerves and vessels in the thoracic region.
Termination and Branching
The brachiocephalic artery has a short course, approximately 4 to 5 cm in length. It travels superiorly and slightly laterally before bifurcating at the level of the right sternoclavicular joint. Here, it divides into its two terminal branches:
- Right Common Carotid Artery: This artery ascends toward the neck and head, supplying blood to the right side of the head and neck. It runs parallel to the left common carotid artery, which arises directly from the aortic arch.
- Right Subclavian Artery: This artery runs laterally and travels under the clavicle to supply blood to the right upper limb and parts of the neck and thorax. It continues as the axillary artery in the arm.
Relationship with Surrounding Structures
The brachiocephalic artery is surrounded by several vital structures, making it an important anatomical landmark in the upper thoracic region:
- Trachea: The artery is located anterior to the trachea, which is the air passage leading to the lungs. The proximity to the trachea is significant during surgeries and in cases of vascular disease.
- Esophagus: The esophagus, which runs posterior to the trachea, is also located close to the brachiocephalic artery. This relationship is important in both vascular and esophageal surgeries.
- Sternum and Manubrium: The artery is positioned deep to the sternum, specifically behind the manubrium, which provides some protection to the artery in this region.
- Right Vagus Nerve and Right Recurrent Laryngeal Nerve: The right vagus nerve passes anterior to the brachiocephalic artery as it descends toward the thorax, while the right recurrent laryngeal nerve, a branch of the vagus, loops around the right subclavian artery after the bifurcation of the brachiocephalic artery.
Variations
Anatomical variations of the brachiocephalic artery can occur, though they are relatively rare. In some cases, the artery may give off additional small branches before bifurcating into the right common carotid and subclavian arteries. Another variation is the absence of the brachiocephalic artery, where the right common carotid and subclavian arteries arise directly from the aortic arch, similar to the arteries on the left side of the body.
Length and Size
The brachiocephalic artery is relatively short, measuring approximately 4 to 5 cm in length. It is the largest of the three branches originating from the aortic arch, with a diameter that can vary slightly depending on the individual. The artery’s short length and large size are important factors in its role as a conduit for blood to major regions of the body.
Branches and Bifurcation
The brachiocephalic artery has two main branches:
- Right Common Carotid Artery: The right common carotid artery ascends vertically and supplies the right side of the neck and head. It divides into the internal carotid artery (which supplies the brain) and the external carotid artery (which supplies the face and scalp) in the neck.
- Right Subclavian Artery: The right subclavian artery travels laterally toward the shoulder and right upper limb. It gives off several important branches before becoming the axillary artery, including the vertebral artery, which supplies the brain and spinal cord, and the internal thoracic artery, which supplies the chest wall.
Relationship with the Left-Sided Arteries
Unlike the right side, where the brachiocephalic artery branches into both the right common carotid and right subclavian arteries, the left side of the body has no brachiocephalic artery. Instead, the left common carotid artery and left subclavian artery arise independently from the aortic arch. The asymmetry between the left and right sides reflects the anatomical variation in blood supply from the heart to the head and upper limbs.
Clinical Landmark
The brachiocephalic artery is a significant anatomical and clinical landmark due to its location and branching. It is used as a point of reference during surgical procedures involving the aortic arch, the neck, and the thoracic region. Its bifurcation point at the right sternoclavicular joint is an important anatomical landmark in both diagnostic imaging and surgical planning.
Surrounding Vascular Structures
- Aortic Arch: The brachiocephalic artery arises from the aortic arch, which is located in the superior mediastinum and gives rise to two other major branches: the left common carotid artery and the left subclavian artery.
- Right Subclavian Vein: The right subclavian vein, which returns deoxygenated blood from the right upper limb, runs parallel to the right subclavian artery after the brachiocephalic artery bifurcates.
Termination
The brachiocephalic artery terminates by dividing into the right common carotid artery and the right subclavian artery at the level of the right sternoclavicular joint. These two arteries continue to supply the head, neck, and right upper limb, making the brachiocephalic artery a critical vessel in the upper body’s arterial supply.
Function
Blood Supply to the Right Side of the Head and Neck
The brachiocephalic artery plays a crucial role in supplying oxygenated blood to the right side of the head and neck. It accomplishes this by giving rise to the right common carotid artery, which ascends through the neck and branches into the internal and external carotid arteries. These arteries are responsible for supplying the brain, face, scalp, and other structures in the neck. By providing a direct pathway for oxygenated blood to reach these vital areas, the brachiocephalic artery supports essential functions such as brain activity, sensory perception, and motor control in the head and neck.
Blood Supply to the Right Upper Limb
Another important function of the brachiocephalic artery is to supply blood to the right upper limb, including the shoulder, arm, and hand. The artery achieves this by branching into the right subclavian artery, which travels under the clavicle (collarbone) and toward the upper extremities. The subclavian artery further branches into vessels that supply the chest wall, shoulder, and arm muscles. As the right subclavian artery continues into the arm, it becomes the axillary artery and later the brachial artery, ensuring that the upper limb receives the oxygen and nutrients required for its movement, sensation, and overall function.
Support for Brain Circulation
Through its branch, the right common carotid artery, the brachiocephalic artery indirectly supports brain circulation. The right common carotid artery divides into the internal carotid artery, which supplies blood to the brain, and the external carotid artery, which supplies blood to the face and scalp. The internal carotid artery is a key component of the cerebral arterial circle (Circle of Willis), an anastomotic system that ensures consistent blood flow to the brain. By supporting this system, the brachiocephalic artery helps maintain proper brain perfusion, which is essential for cognitive function, sensory processing, and motor control.
Blood Supply to the Right Thoracic Region
The brachiocephalic artery also contributes to the blood supply of the right thoracic region through branches of the right subclavian artery. One of the subclavian artery’s important branches is the internal thoracic artery, which supplies the chest wall and the anterior intercostal spaces. This artery provides blood to the structures in the anterior thoracic wall, including muscles, bones (such as the ribs), and connective tissues. The brachiocephalic artery, through the subclavian artery, thus ensures that the right thoracic wall and surrounding structures remain well-nourished and functional.
Contribution to the Collateral Circulation in the Brain and Upper Body
The brachiocephalic artery plays an indirect role in collateral circulation, particularly through its branches that contribute to vascular networks in the brain, head, and upper limb. The vertebral artery, a branch of the right subclavian artery, ascends through the neck and enters the cranial cavity to join the basilar artery, forming part of the Circle of Willis. This network allows for collateral circulation to the brain, ensuring that blood flow is maintained even if one of the primary arteries is blocked or compromised. Additionally, the subclavian artery forms anastomoses with branches of the axillary artery and other arteries in the upper limb, ensuring a redundant blood supply to the arm.
Support for Muscle Activity in the Upper Limb
Through its contribution to the right subclavian artery and its branches, the brachiocephalic artery ensures the proper blood supply for the muscles of the right upper limb, including the pectoralis major, deltoid, biceps, triceps, and forearm muscles. These muscles require a continuous supply of oxygen and nutrients during activities such as lifting, pulling, pushing, and fine motor tasks like writing or grasping objects. The brachiocephalic artery supports these functions by enabling the right subclavian artery to supply the oxygenated blood needed for muscular contraction, endurance, and recovery.
Nutrient Delivery and Waste Removal
Like all arteries, the brachiocephalic artery facilitates the delivery of oxygen, glucose, and nutrients to the regions it supplies. Through its branches, it ensures that the right side of the head, neck, and upper limb receive sufficient nutrients to support cellular functions. In addition, the artery plays a role in the removal of metabolic waste products, such as carbon dioxide and lactic acid, from the tissues it supplies. This continuous exchange of oxygen and waste products is critical for maintaining the health of these tissues and preventing issues such as ischemia (lack of oxygen) and muscle fatigue.
Facilitation of Immunological Defense
The brachiocephalic artery indirectly supports the body’s immune defense by delivering blood to lymphoid tissues and immune cells in the right thoracic region, neck, and upper limb. For example, lymph nodes in the axillary and cervical regions rely on a healthy blood supply to function properly in filtering pathogens and supporting immune responses. By delivering oxygenated blood to these areas, the brachiocephalic artery helps maintain the body’s capacity to fight infections and inflammation in the upper body.
Support for Sensory and Motor Function in the Upper Limb
The blood supplied by the brachiocephalic artery, through the right subclavian artery and its branches, supports the sensory and motor functions of the upper limb. The peripheral nerves that control movement and sensation in the arm, hand, and fingers, such as the brachial plexus, rely on an adequate blood supply to remain functional. The brachiocephalic artery ensures that these nerves receive the oxygen and nutrients necessary to transmit motor signals to muscles and sensory signals from the skin and joints back to the central nervous system.
Contribution to Thoracic and Cervical Vascular Networks
The brachiocephalic artery, through its bifurcation into the right common carotid and right subclavian arteries, plays a role in the vascular networks that supply the cervical region (neck) and thoracic region. The right common carotid artery, for example, supports the cervical vascular network that supplies the thyroid gland, trachea, and esophagus, while the right subclavian artery contributes to the thoracic network, supplying the upper chest, clavicle, and first ribs. This extensive distribution of blood is essential for maintaining the metabolic needs of these areas.
Thermoregulation in the Upper Body
The brachiocephalic artery indirectly contributes to thermoregulation in the upper body by delivering blood to the right upper limb and thoracic wall. Blood flow to the skin and muscles of the arm, shoulder, and chest helps to regulate body temperature by dissipating heat when needed and conserving warmth in colder conditions. The right subclavian artery, as a branch of the brachiocephalic artery, plays a key role in adjusting blood flow to the surface tissues of the upper limb, allowing the body to maintain temperature homeostasis.
Clinical Significance
The brachiocephalic artery is clinically significant due to its role in supplying blood to the right side of the head, neck, and upper limb. As the first and largest branch of the aortic arch, it is crucial in maintaining blood flow to these regions.
Cardiovascular Conditions
The brachiocephalic artery is prone to atherosclerosis, which can lead to stenosis (narrowing) or occlusion (blockage). This can result in reduced blood flow to the brain (causing transient ischemic attacks or stroke), upper limb, or neck, requiring interventions such as angioplasty or bypass surgery.
Aneurysms
Aneurysms in the brachiocephalic artery, though rare, can occur and pose a serious risk of rupture, leading to life-threatening internal bleeding. Surgical repair may be required in such cases.
Surgical Considerations
The brachiocephalic artery is often encountered in cardiac and thoracic surgeries, especially during aortic arch repair, bypass surgeries, or the treatment of trauma to the mediastinum. Its location near vital structures like the trachea and right vagus nerve makes it a critical artery to avoid during invasive procedures.
