Anterior inferior cerebellar artery

Last revised by Mostafa El-Feky on 4 Jun 2022

The anterior inferior cerebellar artery (AICA) is one of three vessels that provides arterial blood supply to the cerebellum. It has a variable origin, course and supply, with up to 40% of specimens not having an identifiable standard AICA. The amount of tissue supplied by the AICA is variable (AICA-PICA dominance) but usually includes:


99% of AICAs arise from the basilar artery, but where along the vessel is variable:

  • 75% lower third
  • 16% middle third
  • 9% vertebrobasilar junction


  • internal auditory branch (80% single, 20% double) passes into the IAM
  • lateral branch passes around the flocculus and into the hemispheric fissure (supplying both superior and inferior semilunar lobules)
  • medial branch supplies the biventral lobule

Before cross-sectional imaging, the AICA (along with venous displacement) was used to identify posterior fossa intra- or extra-axial masses, especially at the CP angle. Extra-axial masses (e.g. vestibular schwannomas or meningiomas) would displace the vessel whereas intra-axial masses tend not to.

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Cases and figures

  • Figure 1: normal COW anatomy
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  • Figure 2: origin of the cerebellar arteries
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  • Figure 3: posterior fossa vascular territories
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  • Figure 4: mid-cerebellum
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  • Figure 5: PICA, AICA and SCA
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  • Figure 6: brainstem arterial territories
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