Written by Andrea Fields MHA, RDCS

Carotid Artery Anatomy

Our next blog series is going to cover the basic material needed to complete a carotid ultrasound study. First, we need to review basic anatomy!

Aortic Arch

Aortic Arch

Aortic Arch Branches:

  1. Brachiocephalic Artery (Innominate)
  2. Left Common Carotid Artery (CCA)
  3. Left Subclavian Artery

Brachiocephalic Artery

  • First branch off of aortic arch
  • Supplies blood to right arm, neck, head
  • Branches into:
    1. Right Common Carotid Artery (CCA)
    2. Right Subclavian Artery

Subclavian Artery

  • Right subclavian artery branches off of brachiocephalic artery
  • Left subclavian artery branches directly off aortic arch
  • Major arteries of upper throax below clavicle
  • Provides blood to arms
    • Right subclavian artery: right arm
    • Left subclavian artery: left arm

Common Carotid Artery (CCA)

Common Carotid Artery (CCA)

  • Paired structure supplying neck & head with oxygenated blood
  • Right CCA: branches off of brachiocelphalic artery
  • Left CCA: branches directly off of aortic arch
  • Move upwards on neck to level of thyroid cartilage
  • Normal Diameter: 0.75 – 1.25 cm

Carotid Artery Bifurcation

Carotid Artery Bifurcation

  • Carotid Bulb: at level of bifurcation, the vessel will become enlarged
  • Bifurcation: division of a vessel into multiple parts
  • CCA Bifurcates into:
    1. Internal Carotid Artery (ICA)
    2. External Carotid Artery (ECA)

Carotid Body

  • Small oval structure that sits behind bifurcation
  • Function: small cluster of chemoreceptors- responds to oxygen (O2), carbon dioxide & pH levels in blood
  • Glossopharyngeal Nerve: provides motor & sensory functions

carotid body

Carotid Sinus

  • Localized dilatation at origin of ICA & bifurcation of CCA
  • Function: baroreceptor (pressure receptor)- regulates & maintains blood pressure

Carotid sinus

External Carotid Artery (ECA)

External Carotid Artery ECA


  • Begins at bifurcation of CCA
  • Travels upwards & terminates at superficial temporal artery (STA)
  • Courses anterior & medial
  • Smaller than ICA
  • 1st major branch: superior thyroid artery
  • Help distinguish between ECA & ICA
  • Branches supply face, neck & head
  • Develop collateral blood supply when carotid & vertebral disease present
  • Normal Diameter: 0.25 – 0.70 cm

Internal Carotid Artery (ICA)

 Internal Carotid Artery ICA

  • Begins at bifurcation of CCA
  • Travels upwards as single vessel until enters cranium (terminates)
  • Courses posterior & lateral
  • No branches within neck area
  • Provides 75% blood supply to brain
  • Normal Diameter: 0.5 – 1.0 cm
  • Shape Distortions: due to embryologic, pathologic or aging
    1. Tortuous
    2. Kinked- associated with cerebral ischemia symptoms
    3. Coiled


Review of basic anatomy is a helpful to in order to fully understand how to evaluate and assess for pathology!

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