What Are Carotid Arteries?

Carotid arteries are the primary paired vessels that deliver oxygenated blood to the brain, face, and neck. Each side of the neck contains a common carotid artery (CCA) that bifurcates, typically at the level of the fourth or fifth cervical vertebra, into the internal carotid artery (ICA) and the external carotid artery (ECA). The ICA ascends without branching in the neck and enters the skull to supply the cerebral hemispheres and eyes through its contribution to the circle of Willis, while the ECA branches extensively to supply the face, scalp, and neck structures. As described in StatPearls anatomy resources at NCBI, the carotid bifurcation is one of the most clinically significant vascular locations in the body because atherosclerotic plaque preferentially forms there.

The study of carotid arteries sits at the intersection of vascular anatomy, hemodynamics, neurology, and biomedical imaging. Engineers and clinicians alike focus on this vessel pair because its stenosis is one of the leading preventable causes of ischemic stroke, and its accessible location in the neck makes it amenable to both non-invasive ultrasound imaging and surgical intervention.

Anatomy and Hemodynamics

The common carotid arteries arise differently on each side: on the right from the brachiocephalic trunk, and on the left directly from the aortic arch. Like most large arteries, the CCAs consist of three concentric wall layers: the tunica intima, tunica media, and tunica adventitia. At the bifurcation, the carotid bulb is a focal dilation that contains the carotid sinus, a baroreceptor region sensitive to stretch and central to blood pressure regulation through the baroreflex. The geometry of the bifurcation produces complex, often disturbed flow patterns including recirculation zones and oscillatory wall shear stress, which are mechanistically associated with endothelial activation and the early stages of atherosclerotic plaque formation.

Atherosclerosis and Carotid Stenosis

Atherosclerosis of the carotid arteries, most commonly at the bifurcation and proximal ICA, is a major cause of transient ischemic attack (TIA) and ischemic stroke. Plaque accumulation narrows the arterial lumen, reducing blood flow and creating conditions favorable for thrombus formation. Emboli shed from unstable plaques can travel to the cerebral circulation and occlude smaller vessels, producing focal neurological deficits. The degree of stenosis, measured as percentage reduction of the luminal diameter, is used to stratify stroke risk and guide treatment decisions. Significant stenosis is defined by most guidelines as 50 percent or greater, with high-grade stenosis above 70 percent generally prompting consideration of intervention.

Imaging and Intervention

Several imaging modalities are used to evaluate carotid arterial disease. Duplex ultrasound combines B-mode structural imaging with Doppler velocity measurement to assess plaque morphology and flow characteristics non-invasively. CT angiography (CTA) and magnetic resonance angiography (MRA) provide three-dimensional vessel reconstructions that characterize plaque extent and distal anatomy. Digital subtraction angiography (DSA) remains the reference standard for quantifying stenosis when other modalities are inconclusive. Carotid endarterectomy (CEA), a surgical procedure to remove atherosclerotic plaque from the vessel wall, has a well-established evidence base for symptomatic high-grade stenosis. Carotid artery stenting (CAS), performed via catheter, provides an alternative in patients at elevated surgical risk, as documented in carotid stenosis resources from the Radiological Society of North America.

Applications

Carotid artery research and clinical management intersect with many fields, including:

• IEEE Transactions on Biomedical Engineering research on ultrasound signal processing and plaque characterization algorithms
• Computational fluid dynamics modeling of bifurcation hemodynamics for stent design
• Stroke prevention programs combining imaging surveillance with medical therapy
• Surgical and interventional training for endarterectomy and carotid stenting procedures
• Wearable carotid pulse sensing for non-invasive blood pressure estimation