Notes

Thomas Willis first described this vascular anatomy in 1664.

The internal carotid artery system, which perfuses the anterior cerebrum.
The vertebral-basilar system, which perfuses the posterior cerebrum. The basliar artery (which ascends the brainstem) forms from a pair of vertebral arteries that rise to the base of the brain.
Communicating arteries connect these systems.
- Clinical Correlations: Arteries of the Neck & Video on cartoid & vertebral artery dissections

Middle cerebral arteries (MCA)
- Extend laterally
- Clinical Correlation: MCA Stroke
Anterior cerebral arteries (ACA)
- Extend anteriorly
- Clinical Correlation: ACA Stroke

The basilar artery bifurcates at its apex.
- Clinical Correlation: Basilar occlusion
Show that it divides into the:
Posterior cerebral arteries & the Cerebellar vessels
- Clinical Correlation: PCA Stroke
Show the Cerebellar Vessels from superior to inferior:
- Superior cerebellar artery (SCA) off the superior portion of the basilar artery.
- Anterior inferior cerebellar artery (AICA) off the inferior portion of the basilar artery.
- Posterior inferior cerebellar artery (PICA) off the vertebral artery.
- Clinical correlation: Wallenberg syndrome

A posterior communicating artery connects each internal carotid artery and posterior cerebral artery
- It connects the internal carotid and vertebral-basilar systems.
The anterior communicating artery connects the bilateral anterior cerebral arteries.
- These arterial communications helps to preserve blood flow to susceptible brain areas in the setting of vertebral or carotid arterial occlusion: it connects the bilateral cerebrovascular system.

Anterior spinal artery forms from vertebral arteries combine, inferiorly.
Basilar perforators:
- Pontine paramedian arteries
- Short pontine circumferential arteries
- Long pontine circumferential arteries