Where is it located and how does it run?
The brachiocephalic trunk is located in the superior mediastinum. The superior mediastinum lies above the imaginary plane drawn through the superior margin of the roots of the lungs.
It arises from the convex surface of the aortic arch (arcus aortae), being its first branch (from right to left). The origin of the trunk lies slightly to the left of the midline, after which the vessel, about 4 cm long, runs upward and to the right toward the right sternoclavicular joint, where it divides into the right common carotid and right subclavian arteries. The trunk is projected onto the anterior thoracic wall in the region of the manubrium of the sternum.
Topography and adjacent structures
The brachiocephalic trunk has close topographic relationships with the organs and vessels of the mediastinum and neck:
- Anteriorly: the trunk is separated from the manubrium of the sternum by the left brachiocephalic vein (v. brachiocephalica sinistra), as well as the sternohyoid and sternothyroid muscles. Right and anteriorly, it is partially covered by the mediastinal pleura.
- To the right: the right brachiocephalic vein runs along the right wall of the artery. In the region of the brachiocephalic veins lie the brachiocephalic lymph nodes (nodi lymphoidei brachiocephalici).
What branches does it divide into?
At the level of the right sternoclavicular joint, the brachiocephalic trunk divides into the right common carotid and right subclavian arteries:
- Right common carotid artery (a. carotis communis dextra) — ascends in the neck without giving off branches until its bifurcation. It enters the carotid arterial system.
- Right subclavian artery (a. subclavia dextra) — gives rise to the vertebral artery (a. vertebralis). The vertebral artery is a crucial source of blood supply to the upper cervical segments of the spinal cord and enters the vertebrobasilar system.
Additional branch: sometimes the thyroid ima artery (a. thyroidea ima) arises directly from the brachiocephalic trunk.
Anatomic variations
The anatomy of the aortic arch branches is variable. The following variations have been described for the brachiocephalic trunk:
- The trunk may be completely absent. In this case, the right common carotid and right subclavian arteries arise directly from the aortic arch.
- The trunk may arise from the left side of the aortic arch.
- In rare cases, two brachiocephalic trunks — right and left — are formed.
Clinical significance
- Atherosclerosis: the brachiocephalic trunk is one of the typical sites for arterial stenoses and occlusions.
- Aortic surgery: during "open" surgical correction of an aortic arch aneurysm under circulatory arrest, antegrade cerebral perfusion is recommended. The brachiocephalic trunk is one of the preferred access zones for arterial cannulation. The use of an additional synthetic vascular graft is recommended.
Class and exam questions
Which vein separates the brachiocephalic trunk from the manubrium of the sternum?
The trunk is separated from the manubrium of the sternum by the left brachiocephalic vein (v. brachiocephalica sinistra).
At what level does the brachiocephalic trunk divide into its terminal branches?
Bifurcation of the trunk into the right common carotid and right subclavian arteries occurs at the level of the right sternoclavicular joint.
To which compartment of the mediastinum does the brachiocephalic trunk belong?
It is located in the superior mediastinum — above the imaginary plane drawn through the upper margin of the roots of the lungs.
What else to study on this topic
- Aortic arch (arcus aortae)
- Right common carotid artery (a. carotis communis dextra)
- Right subclavian artery (a. subclavia dextra)
- Superior mediastinum
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