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 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)

• 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 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 Sinus

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

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)

• 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

Summary

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