Circle of Willis
Circle of Willis
- The internal carotid artery system
- Perfuses the anterior cerebrum.
- The vertebral-basilar system
- 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.
internal carotid artery: Major Branches
- Middle cerebral arteries (MCA)
- Extend laterally
- Anterior cerebral arteries (ACA)
- Extend anteriorly
basilar artery ANATOMY
Major Branches
- The basilar artery bifurcates at its apex.
It divides into the:
- Posterior cerebral arteries & the Cerebellar vessels
The Cerebellar vessels (from superior to inferior) are:
- Superior cerebellar artery (SCA)
- Anterior inferior cerebellar artery (AICA)
- Posterior inferior cerebellar artery (PICA)
communicating arteries
- A posterior communicating artery connects each internal carotid artery and posterior cerebral artery
- 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.
Internal Carotid: Additional, Key Branches
- The lenticulostriate branches of the middle cerebral artery.
- The anterior choroidal branch of the internal carotid artery.
Brainstem perforators
- Anterior spinal artery forms from vertebral arteries combine, inferiorly.
- Basilar perforators:
- Pontine paramedian arteries
- Short pontine circumferential arteries
- Long pontine circumferential arteries