External Carotid Artery
The external carotid artery is a major blood vessel in your neck that supplies blood to many structures of the head and neck, except for the brain itself. When you see this term mentioned in a radiology report, it’s referring to one of the two main branches that split from the common carotid artery. While the internal carotid artery delivers blood to your brain, the external carotid artery provides essential blood supply to your face, scalp, jaw, and neck tissues.
Key Branches of the External Carotid Artery
The external carotid artery divides into several important branches, each serving different areas of your head and neck. Understanding these branches helps make sense of what radiologists look for on imaging studies:
Superior Thyroid Artery
This first branch supplies blood to your thyroid gland and the muscles in your neck and larynx (voice box). On imaging, it appears as a small vessel descending from the external carotid artery toward the thyroid gland at the base of your neck.
Facial Artery
The facial artery brings blood to your face, including the lips, nose, and areas around the mouth. On scans, radiologists can follow its winding path as it crosses the jawbone and curves upward across your face.
Lingual Artery
This branch supplies your tongue with blood. Radiologists can identify it as it branches off and travels forward beneath the tongue. Any blockages here can affect tongue function and speech.
Occipital Artery
The occipital artery provides blood to the back of your scalp and the deep muscles at the back of your neck. On imaging, it can be seen traveling backward along the skull base.
Maxillary Artery
As the largest branch, the maxillary artery supplies blood to deep facial structures, including teeth, jaw muscles, and sinuses. It’s an important landmark on head and neck imaging studies.
How the External Carotid Artery Appears on Different Imaging Tests
CT Angiography (CTA)
On a CT angiogram, the external carotid artery appears as a bright white vessel when contrast dye is used. Radiologists can track its path from where it branches off the common carotid artery in the neck to its various branches throughout the head and face. The contrast makes blood vessels stand out against surrounding tissues, allowing doctors to detect narrowing or blockages.
Magnetic Resonance Angiography (MRA)
MRA shows the external carotid artery without using radiation. On these images, flowing blood appears either bright or dark (depending on the technique used), allowing radiologists to examine the vessel’s structure and blood flow patterns.
Ultrasound
During a carotid ultrasound, the external carotid artery appears as a pulsating tubular structure. Ultrasound is especially useful for showing blood flow in real-time. Radiologists can see the blood moving through the vessel and measure its speed, which helps identify areas of narrowing or blockage.
Common External Carotid Artery Findings on Radiology Reports
Stenosis (Narrowing)
When your radiology report mentions “stenosis” of the external carotid artery, it means the vessel has narrowed, typically due to plaque buildup. The report might include percentages to indicate how severe the narrowing is:
- Mild stenosis: Less than 50% narrowing
- Moderate stenosis: 50-69% narrowing
- Severe stenosis: 70% or greater narrowing
In my practice, this finding often indicates underlying atherosclerosis—the same process that affects arteries throughout the body. While external carotid stenosis isn’t as immediately concerning as internal carotid stenosis (which can cause strokes), it still requires attention, especially if symptoms like facial pain occur.
Tortuosity
“Tortuosity” on a radiology report means the external carotid artery has an unusually winding or twisted course. This is fairly common, especially in older adults and those with high blood pressure. While often just a normal variant, significant tortuosity can sometimes affect blood flow.
Aneurysm
An aneurysm is a balloon-like bulge in the artery wall. External carotid aneurysms are rare but may appear on imaging as rounded outpouchings from the normal vessel contour. These require careful monitoring and sometimes treatment to prevent rupture.
Dissection
A dissection occurs when blood forces its way between the layers of the artery wall, creating a false channel. On imaging, this appears as an irregular vessel contour with a “double lumen” (two channels where there should be only one). This finding requires prompt medical attention.
Clinical Significance of External Carotid Artery Imaging
Understanding abnormalities of the external carotid artery is particularly important for several reasons:
Presurgical Planning
Before facial or neck surgery, detailed imaging of the external carotid artery helps surgeons map out important blood vessels they need to protect or navigate around. Radiologists typically note this when preparing patients for procedures like tumor removal or facial reconstruction.
Bleeding Management
In cases of severe facial trauma or nosebleeds that won’t stop, doctors may need to identify which branch of the external carotid artery is bleeding. Imaging helps guide treatments like embolization—a procedure that deliberately blocks problematic blood vessels.
Tumor Blood Supply
Head and neck tumors often receive their blood supply from branches of the external carotid artery. Imaging can show which specific vessels feed a tumor, helping oncologists plan targeted treatments.
When to Be Concerned About External Carotid Artery Findings
While internal carotid artery problems often get more attention due to stroke risk, external carotid artery issues can still cause significant symptoms:
- Facial pain or headaches
- Pulsating sensation in the ear
- Difficulty chewing (jaw claudication)
- Scalp tenderness
- Facial numbness or weakness
If your radiology report mentions abnormalities of the external carotid artery and you experience any of these symptoms, discuss them with your doctor to determine appropriate follow-up.
Conclusion
The external carotid artery plays an important role in delivering blood to your face, scalp, and neck. When this vessel appears on radiology reports, radiologists are evaluating for abnormalities or to help plan treatments. Understanding the normal anatomy and common findings can help you better understand your imaging results and have more informed discussions with your doctor.
References
- https://radiopaedia.org/articles/external-carotid-artery-1?lang=us
- https://www.physio-pedia.com/External_Carotid_Artery
- https://www.jvascsurg.org/article/S0741-5214(05)01101-8/fulltext