L4.5.3: Circle of Willis

• CIRCLE OF WILLIS

  ● “Cerebral arterial circle”

  ● Protects the brain by providing more than one route for blood to reach brain tissue in case of a clot or impaired blood flow anywhere in the system
• CIRCLE OF WILLIS

  ● Internal carotid arteries divide into:

  ○ Anterior and middle cerebral arteries (supply most of the cerebrum)

  ○ Vertebral arteries join once within the skull to form the basilar artery (serves the brain stem and cerebellum)
• CIRCLE OF WILLIS ● Internal carotid arteries divide into:

  ○ Posterior cerebral arteries form from the division of the basilar artery, supplying the posterior cerebrum

  ○ Anterior and posterior blood supplies are united by small communicating arterial branches

  ○ Result—complete circle of connecting blood vessels, circle of Willis