The innominate artery is the first and largest branch off the aortic arch, the curved section of the main artery leaving your heart. Its job is to carry oxygen-rich blood to the right side of your head, neck, and right arm. You may also see it called the brachiocephalic artery or brachiocephalic trunk, which is the more modern anatomical term. “Innominate” literally means “unnamed,” a holdover from early anatomists who hadn’t yet settled on a label for it.
Where It Sits and Where It Goes
The innominate artery branches off the top of the aortic arch, slightly to the right and in front of the next branch (the left common carotid artery). It travels upward and to the right through the upper chest for roughly 4 centimeters on average, though cadaveric studies have measured it as short as 1.7 cm and as long as 6 cm depending on the person. Its internal diameter is about 12 millimeters in a healthy adult.
At roughly the level of the sternoclavicular joint, where your collarbone meets your breastbone, it splits into two vessels:
- Right common carotid artery: carries blood up to your brain, face, and neck on the right side.
- Right subclavian artery: supplies your right arm and also sends smaller branches to parts of your head, neck, and chest wall.
The left side of your body doesn’t have an equivalent single trunk. Instead, the left common carotid and left subclavian arteries branch directly off the aortic arch as separate vessels. This asymmetry is why the innominate artery exists only on the right.
What It Supplies
Because it feeds both the right carotid and right subclavian systems, the innominate artery is responsible for oxygenating a broad territory: the right side of your brain, the right side of your face and neck, your right shoulder, and your entire right arm down to the fingertips. Blockage or damage to this single vessel can therefore affect both brain circulation and arm blood flow simultaneously, which is what makes it clinically important despite its short length.
Narrowing and Blockage
Like any artery, the innominate can develop atherosclerosis, a buildup of fatty plaque that narrows the channel. Symptoms depend on which downstream territory loses blood flow. Arm-related symptoms include muscle fatigue or cramping during activity (claudication), rest pain, and in severe cases, tissue damage in the fingers. Neurological symptoms can be more alarming: dizziness, vertigo, difficulty speaking, visual disturbances, loss of coordination, or fainting, all from reduced blood flow to the brain.
One of the simplest screening clues is a blood pressure difference between your two arms. A systolic reading more than 15 mmHg higher in one arm compared to the other suggests significant narrowing somewhere in the arterial supply to the lower-pressure side. Doctors will also listen for abnormal whooshing sounds (bruits) over the neck and above the collarbone. Imaging with CT angiography or magnetic resonance angiography can then map the exact location and severity of the blockage.
Tracheal Compression in Children
In some infants, the innominate artery crosses in front of the windpipe at a slightly abnormal angle and presses against it. This is called innominate artery compression syndrome, and it typically shows up in the first weeks to months of life. Affected babies develop noisy breathing on exhalation (stridor), a dry cough, and sometimes recurrent lung infections or brief pauses in breathing.
A chest X-ray may show the trachea being pushed inward, but CT angiography is the definitive tool for seeing exactly how the artery relates to the airway. When symptoms are mild, children often outgrow the compression as the chest grows. Persistent or worsening cases may need surgery to reposition the artery away from the trachea.
Tracheoinnominate Fistula
One of the most dangerous complications involving this artery is a tracheoinnominate fistula, an abnormal connection that forms between the innominate artery and the windpipe. It occurs almost exclusively in people who have a tracheostomy tube in place. The tube can erode through the tracheal wall into the artery over time, causing sudden, massive bleeding into the airway. This complication is rare, but a systematic review of 121 cases found a mortality rate of 64.5%, making it one of the most lethal vascular emergencies. It typically requires immediate surgery.
Anatomical Variations
Not everyone’s aortic arch branches follow the textbook pattern. In the most common variation, sometimes called a “bovine arch,” the innominate artery and the left common carotid share a single origin from the aorta rather than branching separately. Estimates of how often this occurs vary, but it’s generally considered present in roughly 10 to 25 percent of the population. Most people with this variant never know they have it because it doesn’t cause symptoms. It becomes relevant mainly for surgeons and radiologists who need to plan procedures involving the aortic arch or its branches.
How It’s Evaluated
When a problem with the innominate artery is suspected, imaging is the primary tool. Ultrasound, particularly in pediatric cases, is often the first step because it’s noninvasive, inexpensive, and avoids radiation. For more detailed evaluation, CT angiography provides high-resolution three-dimensional images of the vessel, its branches, and their relationship to surrounding structures like the trachea. Magnetic resonance angiography is an alternative that avoids radiation exposure but may require sedation in young children. Older techniques like catheter angiography are now largely reserved for situations where treatment can be performed at the same time as imaging.
Blood pressure measurement in both arms remains a valuable, low-tech screening tool. It costs nothing, takes seconds, and a difference greater than 15 mmHg is enough to prompt further investigation of the vessels supplying the upper body.