Brachiocephalic trunk
Truncus brachiocephalicus
Also known as: innominate artery, brachiocephalic artery
The brachiocephalic trunk is the first and largest branch of the aortic arch. It ascends behind the manubrium and divides behind the right sternoclavicular joint into the right common carotid and right subclavian arteries.
Overview
The trunk is about 4–5 cm long. It begins behind the middle of the manubrium and runs upward and to the right, at first in front of the trachea and then to its right. It ends behind the right sternoclavicular joint.
It normally gives off no branches before it divides. In a minority of people, however, it gives rise to a small thyroid ima artery that runs up in front of the trachea to the isthmus of the thyroid gland. There is no brachiocephalic trunk on the left: the left common carotid and left subclavian arteries arise directly from the arch.
In a common variant, the "bovine arch", the left common carotid artery arises from the brachiocephalic trunk or shares a common origin with it. Imaging series report this in roughly 15–25% of people.
- Location
Superior mediastinum, behind the manubrium, between the arch of the aorta and the right sternoclavicular joint.
Anatomy
- Branches
The right common carotid artery and the right subclavian artery. Occasionally it also gives a thyroid ima artery.
- Relations
In front: the manubrium, the left brachiocephalic vein (crossing it), the thymic remnants and the sternohyoid and sternothyroid muscles. Behind and to the left: the trachea. To the right: the right brachiocephalic vein, the SVC and the right pleura.
Function
- Carries blood to the right side of the head and neck and to the right upper limb.
Clinical significance
Tracheo-innominate fistula
A tracheostomy placed too low, or a tube cuff inflated to high pressure, can erode through the front of the trachea into the brachiocephalic trunk. This causes catastrophic bleeding, often preceded by a smaller "herald" bleed.
Thyroid ima artery
A thyroid ima artery, when present, is at risk during tracheostomy and thyroid surgery.
Compiled from standard anatomy and physiology references — see the Cardiovascular System sources. For education only; not medical advice.