The Anatomy of the Costocervical Trunk

The costocervical trunk is an artery that supplies blood to the head and neck. A paired vessel that appears on both sides of the neck, this artery is a branch of the subclavian artery in the shoulder which delivers blood to the upper extremities.

It emerges just above the clavicle at the base of the neck. Moving posterolaterally (toward the side and back), it runs a short course before dividing into two major branches: the deep cervical and supreme intercostal arteries.

Since it serves such an important role, problems with the costocervical trunk can have serious clinical implications. Obstructions here or of the subclavian artery can also be very disruptive. 

The costocervical trunk can be subject to inflammation, Takayasu arteritis, pseudoaneurysm, or accidents in which it is pierced or damaged.

Anatomy

On each side of the base of the neck, the costocervical trunk, via its branches, connects the subclavian artery to the occipital and vertebral arteries of the head and neck.  

Structure and Location

Located in each shoulder, the subclavian arteries are major arteries of the chest (thorax) running toward the sides of the body just beneath the clavicles, or collar bones. The costocervical trunk emerges from these around the level of the base of the neck.

It has a very short course that runs through the suprapleural membrane, a connective tissue, over the top portion of the lung. Here’s a quick breakdown of its course.

Origin and Course

Though there may be some variation, the costocervical trunk arises from the upper portion of the distal segment of the subclavian artery, which is the portion that runs outward toward the shoulders.

It emerges just past the thyrocervical trunk, behind or medial to (closer to the middle of) the anterior scalene muscle of the front of the neck.   

Superior Intercostal Artery

The superior intercostal artery branch bends backward, looping around the neck of the first (top-most) rib. It then passes between the stellate ganglion, a bundle of nerves at the level of the lowest neck vertebrae, and the extending, outer portion of the spinal nerve, moving downward.

Finally, it descends along the inside of the rib cage where it terminates into several branches.    

Deep Cervical Artery

Running to the back and side until it passes over the upper rib, the deep cervical artery branch then curls upward, parallel to the spine in the neck (cervical spine) and in front of the posterior (rear) neck muscles.

It gives off several of its own branches, and at the level of the second cervical vertebra, it connects with the descending branch of the occipital artery.

Anatomical Variations

As is the case with other arteries and veins in the body, there are a number of variations to the anatomy of the costocervical trunk. These are quite common, and most don’t impact function. They include:

• Earlier origin: In about 40% of cases, the costocervical trunk emerges from the subclavian artery closer to the middle of the body. The origin of this artery may also vary from side to side.
• Accessory deep cervical artery: A second deep cervical artery branches off from the costocervical trunk in 25% of people.
• Absent superior intercostal artery: Doctors have also observed the absence of this branch. In these cases, this artery is replaced with a branch of the descending aorta. The superior intercostal artery may then arise from other arteries, such as the thyrocervical trunk, the deep cervical artery, and the inferior thyroid artery.

Function

Like all arteries, the costocervical trunk is part of the circulatory system tasked with delivering oxygenated blood from the heart to the tissues, muscles, bones, and other parts of the body. Its function can be broken down based on its branches:

• Via its superior intercostal branch, the costocervical supplies the uppermost intercostal spaces, which are those between the ribs. This branch also brings blood to muscles, tissues, and skin in these areas.
• Its deep cervical branch provides blood to the posterior (rear) muscles of the neck. This artery also has a branch that enters the cervical spinal canal, the area created by the vertebrae for the spinal cord itself.

Clinical Significance

Given that the costocervical trunk is an important part of the circulatory system providing blood for parts of the upper body, damage or disorder here can have serious implications. Most prevalent among these are:

• Takayasu arteritis: Also known as pulseless disease, this condition occurs when larger arteries like the subclavian artery and its branches become inflamed. Doctors detect this when they hear bruits—abnormal “murmurs”—through a stethoscope and are unable to detect a radial pulse (the kind detected in the wrist). It can lead to stroke and other issues.    
• Perforation: The costocervical trunk can become perforated during coronary angiography, an imaging approach that tracks blood flow in the body. Though it occurs rarely, this is a medical emergency as blood pools in the neck and starts obstructing airways, calling for immobilization and other emergency treatments.
• Pseudoaneurysm: Leaking blood from the costocervical trunk is a rare complication of bullectomy (a procedure that removes dilated air spaces from the lung), the use of an IV in the jugular vein, or infections or trauma to the neck. This can interrupt breathing and cause chest pain, requiring surgical treatment.
• Collateral blood supply: Disruptions of blood flow can make the intercostal branch of the costocervical trunk particularly important in providing blood to tissues and muscles between the ribs. Notably, when the internal carotid artery becomes blocked, the costocervical trunk may become essential for circulation and is at risk for aneurysm.
• Subclavian steal syndrome: Related to the above, subclavian steal is a reversal of blood flow due to occlusion or stenosis (narrowing) of arteries that supply the subclavian arteries. This condition may be asymptomatic, though it can also lead to arm pain, fainting, and cognitive issues, among other problems.